L-Carnitine supplementation improves the behavioral symptoms in autistic children

ArticleinResearch in Autism Spectrum Disorders 7(1):159–166 · January 2013with 2,376 Reads 
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Abstract
l-Carnitine was proposed as a potential treatment for patients diagnosed with autism to ameliorate the behavioral symptoms associated with the disease. Thirty children diagnosed with autism were randomly assigned to receive (100 mg/kg bodyweight/day) of liquid l-carnitine (n = 16) or placebo (n = 14) for 6 months. Measurements included changes in childhood autism rating scale (CARS) form and free and total carnitine levels using tandem mass spectrometry. Results showed significant improvement in CARS scores (P-groups <0.001) and (P-overtime = 0.006), with statistically significant differences in free carnitine levels (P = 0.027) and total carnitine levels (P = 0.036). There was no correlation between baseline free and total carnitine levels with changes in CARS scores from zero to 6 months (r > 0.5, P > 0.05) and generally l-carnitine therapy was well tolerated. In conclusion, l-carnitine therapy (100 mg/kg bodyweight/day) administered for 6 months significantly improved the autism severity, but subsequent studies are recommended.

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  • ... Perhaps the best studied cofactor is L-Carnitine. Two medium sizes (n=30, 30) double-blind placebo controlled (DBPC) studies using L-Carnitine treatment (50mg/kg/day for 3 months and 100mg/kg/day for 6 months) found that scores on the Childhood Autism Rating Scale (CARS) improved with L-Carnitine as compared to placebo 39,40 with one study finding that greater symptomatic improvement was correlated with a greater increase in blood carnitine levels. 40 An small (n=10) 8-week open-label trial of L-Carnitine used particularly high doses (up to 400mg/kg/day in three divided doses, maximum of 6,000mg/day) with only one child transiently stopping treatment and three children remaining on a lower dose (200mg/kg/day) because of odor and loose stools. ...
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    Several lines of evidence implicate mitochondria in the pathophysiology of autism spectrum disorder (ASD). In this review we outline some of the evidence supporting this notion as well as discuss novel abnormalities in mitochondrial function that appear to be related to ASD as well as treatments which target the mitochondria and have evidence of usefulness in the treatment of ASD. A suspicion of the mitochondria's involvement in ASD can be traced back to 1985 when lactic acidosis was noted in a subset of children with ASD. A large population-based study in 2007 confirmed this notion and found that a subset of children with ASD (∼4%) could be diagnosed with a definite mitochondrial disease. Further studies suggested that children with ASD and mitochondrial disease may have certain characteristics such as fatigability, gastrointestinal disorders, unusual types of neurodevelopmental regression, seizures and motor delay. Further research examining biomarkers of mitochondrial dysfunction and electron transport chain activity suggested that abnormalities of mitochondrial function could affect a much higher number of children with ASD, perhaps up to 80%. Recent research has identified a type of dysfunction of the mitochondrial in which the activity of the electron transport chain is significantly increased. This novel type of mitochondrial dysfunction may be associated with environmental exposures and neurodevelopmental regression. Several treatments that target the mitochondrial appear to have evidence for use in children with ASD, including cofactors such as L-Carnitine, and the ketogenic diet. Although the understanding of the involvement of the mitochondrial in ASD is evolving, the mitochondrial is clearly a novel molecular target which can be helpful in understanding the etiology of ASD and treatments that may improve function of children with ASD.
  • ... a reported few other significant group differences in measures of behavior or communication. 58 Two RCTs of levocarnitine (moderate 51 and high 42 risk of bias) reported improvements in symptom severity in the levocarnitine group compared with placebo, but scores on other behavioral measures or adverse effects did not differ between groups. 42 In the second RCT, symptom severity did not differ between groups after 6 months of treatment. ...
    Article
    Context: Children with autism spectrum disorder (ASD) frequently use special diets or receive nutritional supplements to treat ASD symptoms. Objectives: Our objective was to evaluate the effectiveness and safety of dietary interventions or nutritional supplements in ASD. Data sources: Databases, including Medline and PsycINFO. Study selection: Two investigators independently screened studies against predetermined criteria. Data extraction: One investigator extracted data with review by a second investigator. Investigators independently assessed the risk of bias and strength of evidence (SOE) (ie, confidence in the estimate of effects). Results: Nineteen randomized controlled trials (RCTs), 4 with a low risk of bias, evaluated supplements or variations of the gluten/casein-free diet and other dietary approaches. Populations, interventions, and outcomes varied. Ω-3 supplementation did not affect challenging behaviors and was associated with minimal harms (low SOE). Two RCTs of different digestive enzymes reported mixed effects on symptom severity (insufficient SOE). Studies of other supplements (methyl B12, levocarnitine) reported some improvements in symptom severity (insufficient SOE). Studies evaluating gluten/casein-free diets reported some parent-rated improvements in communication and challenging behaviors; however, data were inadequate to make conclusions about the body of evidence (insufficient SOE). Studies of gluten- or casein-containing challenge foods reported no effects on behavior or gastrointestinal symptoms with challenge foods (insufficient SOE); 1 RCT reported no effects of camel's milk on ASD severity (insufficient SOE). Harms were disparate. Limitations: Studies were small and short-term, and there were few fully categorized populations or concomitant interventions. Conclusions: There is little evidence to support the use of nutritional supplements or dietary therapies for children with ASD.
  • ... Several antioxidants [70], including vitamin C [71], carnosine [72] and l-carnitine [73,74], have been reported to significantly improve autistic behaviors, suggesting that treatment of oxidative stress could be beneficial for ASD children. Other studies suggest that glutathione metabolism can be improved by vitamins and minerals [25], as well as antioxidants, co-enzyme Q10 and B vitamin supplementation [75], and sapropterin treatment [4] in ASD children. ...
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    An imbalance in glutathione-dependent redox metabolism has been shown to be associated with autism spectrum disorder (ASD). Glutathione synthesis and intracellular redox balance are linked to folate and methylation metabolism, metabolic pathways that have also been shown to be abnormal in ASD. Together, these metabolic abnormalities define a distinct ASD endophenotype that is closely associated with genetic, epigenetic and mitochondrial abnormalities, as well as environmental factors related to ASD. Biomarkers that reflect these metabolic abnormalities will be discussed in the context of an ASD metabolic endophenotype that may lead to a better understanding of the pathophysiological mechanisms underlying core and associated ASD symptoms. Last, we discuss how these biomarkers have been used to guide the development of novel ASD treatments.
  • ... It is possible that treatment of these abnormalities may lead to a reduction in autism behaviors. For example, a number of studies have reported improvements in autism using nutritional supplements and medications which can support mitochondrial function (Geier et al., 2011;Frye and Rossignol, 2012b;Rossignol and Frye, 2012b;Fahmy et al., 2013), reduce oxidative stress (Dolske et al., 1993;Chez et al., 2002;Adams and Holloway, 2004;Rossignol, 2009;Adams et al., 2011;Rossignol and Frye, 2011;Hardan et al., 2012;Ghanizadeh and Moghimi-Sarani, 2013), and decrease inflammation (Stefanatos et al., 1995;Shenoy et al., 2000;Boris et al., 2007;Bradstreet et al., 2007;Asadabadi et al., 2013;Taliou et al., 2013). Additional studies are needed to determine if these types of treatments lead to changes in oxidative stress, mitochondrial dysfunction and immune abnormalities reported in the brains of some individuals with ASD. ...
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    Autism spectrum disorders (ASDs) are a heterogeneous group of neurodevelopmental disorders that are defined solely on the basis of behavioral observations. Therefore, ASD has traditionally been framed as a behavioral disorder. However, evidence is accumulating that ASD is characterized by certain physiological abnormalities, including oxidative stress, mitochondrial dysfunction and immune dysregulation/inflammation. While these abnormalities have been reported in studies that have examined peripheral biomarkers such as blood and urine, more recent studies have also reported these abnormalities in brain tissue derived from individuals diagnosed with ASD as compared to brain tissue derived from control individuals. A majority of these brain tissue studies have been published since 2010. The brain regions found to contain these physiological abnormalities in individuals with ASD are involved in speech and auditory processing, social behavior, memory, and sensory and motor coordination. This manuscript examines the evidence linking oxidative stress, mitochondrial dysfunction and immune dysregulation/inflammation in the brain of ASD individuals, suggesting that ASD has a clear biological basis with features of known medical disorders. This understanding may lead to new testing and treatment strategies in individuals with ASD.
  • ... Treatments that are typically used for patients with mitochondrial disease have been shown to improve functioning in some children with ASD (31). Several studies, including two double-blind, placebo-controlled (DBPC) studies (58,59) and case reports (25,37,(60)(61)(62)(63) have reported improvements in core and associated ASD behaviors with l-carnitine treatment. Two DBPC studies using a multivitamin containing B vitamins, antioxidants, vitamin E, and co-enzyme Q10 reported various improvements in ASD symptoms compared to placebo (64,65). ...
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    Recent studies point to the effectiveness of novel treatments that address physiological abnormalities associated with autism spectrum disorder (ASD). This is significant because safe and effective treatments for ASD remain limited. These physiological abnormalities as well as studies addressing treatments of these abnormalities are reviewed in this article. Treatments commonly used to treat mitochondrial disease have been found to improve both core and associated ASD symptoms. Double-blind, placebo-controlled (DBPC) studies have investigated l-carnitine and a multivitamin containing B vitamins, antioxidants, vitamin E, and co-enzyme Q10 while non-blinded studies have investigated ubiquinol. Controlled and uncontrolled studies using folinic acid, a reduced form of folate, have reported marked improvements in core and associated ASD symptoms in some children with ASD and folate related pathway abnormities. Treatments that could address redox metabolism abnormalities include methylcobalamin with and without folinic acid in open-label studies and vitamin C and N-acetyl-l-cysteine in DBPC studies. These studies have reported improved core and associated ASD symptoms with these treatments. Lastly, both open-label and DBPC studies have reported improvements in core and associated ASD symptoms with tetrahydrobiopterin. Overall, these treatments were generally well-tolerated without significant adverse effects for most children, although we review the reported adverse effects in detail. This review provides evidence for potentially safe and effective treatments for core and associated symptoms of ASD that target underlying known physiological abnormalities associated with ASD. Further research is needed to define subgroups of children with ASD in which these treatments may be most effective as well as confirm their efficacy in DBPC, large-scale multicenter studies.
  • ... Several antioxidants [70], including vitamin C [71], carnosine [72] and l-carnitine [73,74], have been reported to significantly improve autistic behaviors, suggesting that treatment of oxidative stress could be beneficial for ASD children. Other studies suggest that glutathione metabolism can be improved by vitamins and minerals [25], as well as antioxidants, co-enzyme Q10 and B vitamin supplementation [75], and sapropterin treatment [4] in ASD children. ...
  • ... It is possible that treatment of these abnormalities may lead to a reduction in autism behaviors. For example, a number of studies have reported improvements in autism using nutritional supplements and medications which can support mitochondrial function (Geier et al., 2011;Frye and Rossignol, 2012b;Rossignol and Frye, 2012b;Fahmy et al., 2013), reduce oxidative stress (Dolske et al., 1993;Chez et al., 2002;Adams and Holloway, 2004;Rossignol, 2009;Adams et al., 2011;Rossignol and Frye, 2011;Hardan et al., 2012;Ghanizadeh and Moghimi-Sarani, 2013), and decrease inflammation (Stefanatos et al., 1995;Shenoy et al., 2000;Boris et al., 2007;Bradstreet et al., 2007;Asadabadi et al., 2013;Taliou et al., 2013). Additional studies are needed to determine if these types of treatments lead to changes in oxidative stress, mitochondrial dysfunction and immune abnormalities reported in the brains of some individuals with ASD. ...
  • ... Interestingly, treatments that are typically used for patients with mitochondrial disease have been shown to improve functioning in some children with ASD [122]. Several studies, including two double-blind, placebo-controlled studies [183,184], have reported improvements in core and associated ASD behaviors with L-carnitine treatment [140,141,[183][184][185][186][187][188]. Two double-blind, placebo-controlled studies using a multivitamin containing B vitamins, antioxidants, vitamin E, and coenzyme Q10 reported various improvements in ASD symptoms compared with placebo [189,190]. ...
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    Autism spectrum disorder (ASD) affects a significant number of individuals in the United States, with the prevalence continuing to grow. A significant proportion of individuals with ASD have comorbid medical conditions such as epilepsy. In fact, treatment-resistant epilepsy appears to have a higher prevalence in children with ASD than in children without ASD, suggesting that current antiepileptic treatments may be suboptimal in controlling seizures in many individuals with ASD. Many individuals with ASD also appear to have underlying metabolic conditions. Metabolic conditions such as mitochondrial disease and dysfunction and abnormalities in cerebral folate metabolism may affect a substantial number of children with ASD, while other metabolic conditions that have been associated with ASD such as disorders of creatine, cholesterol, pyridoxine, biotin, carnitine, γ-aminobutyric acid, purine, pyrimidine, and amino acid metabolism and urea cycle disorders have also been associated with ASD without the prevalence clearly known. Interestingly, all of these metabolic conditions have been associated with epilepsy in children with ASD. The identification and treatment of these disorders could improve the underlying metabolic derangements and potentially improve behavior and seizure frequency and/or severity in these individuals. This paper provides an overview of these metabolic disorders in the context of ASD and discusses their characteristics, diagnostic testing, and treatment with concentration on mitochondrial disorders. To this end, this paper aims to help optimize the diagnosis and treatment of children with ASD and epilepsy. This article is part of a Special Issue entitled "Autism and Epilepsy".
  • ... Table 1 presents study characteristics from the placebo-controlled trials. Nine studies reported the target of the active intervention as behavior, [32][33][34][35][36][37][38][39][40] whereas seven studies reported the target of intervention as irritability. 5,[41][42][43][44][45] The remaining studies reported the target of intervention as hyperactivity, 4,46 repetitive behavior, 2,13 disruptive symptoms, 47,48 autism severity, 49 aggression 3 and the core symptoms of autism. ...
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    Full-text available
    Large placebo responses in many clinical trials limit our capacity to identify effective therapeutics. Although it is often assumed that core behaviors in children with autism spectrum disorders (ASDs) rarely remit spontaneously, there has been limited investigation of the size of the placebo response in relevant clinical trials. These trials also rely on caregiver and clinical observer reports as outcome measures. The objectives of this meta-analysis are to identify the pooled placebo response and the predictors of placebo response in pharmacological and dietary supplement treatment trials for participants with a diagnosis of ASD. Randomized controlled trials (RCTs) in pediatric ASD, conducted between 1980 and August 2014, were identified through a search of Medline, EMBASE, Web of Science, Cochrane Database of Systematic Reviews and clinicaltrials.gov. RCTs of at least 14 days duration, comparing the treatment response for an oral active agent and placebo using at least one of the common outcome measures, were included. Analysis of 25 data sets (1315 participants) revealed a moderate effect size for overall placebo response (Hedges' g=0.45, 95% confidence interval (0.34-0.56), P<0.001). Five factors were associated with an increase in response to placebo, namely: an increased response to the active intervention; outcome ratings by clinicians (as compared with caregivers); trials of pharmacological and adjunctive interventions; and trials located in Iran. There is a clear need for the identification of objective measures of change in clinical trials for ASD, such as evaluation of biological activity or markers, and for consideration of how best to deal with placebo response effects in trial design and analyses.
  • ... For many such trials the compounds tested showed little or no measureable efficacy relative to controls [1,21]. Some compounds where double-blind trials did show statistically significant efficacy relative to control are: n-acetylcysteine where Hardan et al., found irritability decreased based on the Aberrant Behavioral Checklist (ABC) irritability subscale [22]; sulforaphane where Singh et al., found behavior improved based on an ABC and Social Responsiveness Scale measures [23]; l-carnitine where Fahmy et al., found behavior improved based on a Childhood Autism Rating Scale [24]; and a multivitamin that contained substantial amounts of methyl-sufonyl-methane and n-acetyl cysteine where Adams et al., found behavior improved based on a Parental Global Impressions measure [25]. What do these compounds have in common beyond their efficacy in autism? ...
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    Many of those with autism have biochemistry that is characterized by high levels of oxidative stress and low levels of sulfur antioxidants. Of the small set of compounds which have been shown to have some efficacy in
  • ... Similarly, the results of this study suggest that low levels of maternal carnitine may be correlated with the likelihood of having had a child later diagnosed with ASD. Previous studies have demonstrated that carnitine supplementation is beneficial for children with ASD (32)(33)(34). It is important to note that the results for this pilot study are for maternal levels post-pregnancy, so they are only suggestive of possible nutritional and metabolic differences during pregnancy. ...
    Preprint
    Full-text available
    Background: Previous research studies have demonstrated abnormalities in the metabolism of mothers of young children with autism. Method: Metabolic analysis was performed on blood samples from 30 mothers of young children with Autism Spectrum Disorder (ASD-M) and from 29 mothers of young typically-developing children (TD-M). Targeted metabolic analysis focusing on the folate one-carbon metabolism (FOCM) and the transsulfuration pathway (TS) as well as broad metabolic analysis were performed. Statistical analysis of the data involved both univariate and multivariate statistical methods. Results: Univariate analysis revealed significant differences in 5 metabolites from the folate one-carbon metabolism and the transsulfuration pathway and differences in an additional 48 metabolites identified by broad metabolic analysis, including lower levels of many carnitine-conjugated molecules. Multivariate analysis with leave one-out cross validation allowed classification of samples as belonging to one of the two groups with 93% sensitivity and 97% specificity with five metabolites. Furthermore, each of these five metabolites correlated with 8-15 other metabolites indicating that there are five clusters of correlated metabolites. In fact, all but 5 of the 50 metabolites with the highest area under the receiver operating characteristic curve were associated with the five identified groups. Many of the abnormalities appear linked to low levels of folate, vitamin B12, and carnitine-conjugated molecules. Conclusions: Mothers of children with ASD have many significantly different metabolite levels compared to mothers of typically developing children at 2-5 years after birth.
  • ... Several studies have reported improve ments in core and associated ASD behaviors with l-carnitine treatment, 20,31,[245][246][247][248] including two DBPC studies. 249,250 One DBPC study demonstrated that increases in serum carnitine levels correlated with improvements in cognitive and behavioral indexes in children with ASD. 249 Carnitine has been suggested to help children with ASD and abnormal PPA metabolism, 113 and a recent genetic disorder associated with ASD and abnormal carnitine metabolism could be responsive to supplemental carnitine. ...
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    Full-text available
    Despite the fact that the prevalence of autism spectrum disorder (ASD) continues to rise, no effective medical treatments have become standard of care. In this paper we review some of the pathophysiological abnormalities associated with ASD and their potential associated treatments. Overall, there is evidence for some children with ASD being affected by seizure and epilepsy, neurotransmitter dysfunction, sleep disorders, metabolic abnormalities, including abnormalities in folate, cobalamin, tetrahydrobiopterin, carnitine, redox and mitochondrial metabolism, and immune and gastrointestinal disorders. Although evidence for an association between these pathophysiological abnormalities and ASD exists, the exact relationship to the etiology of ASD and its associated symptoms remains to be further defined in many cases. Despite these limitations, treatments targeting some of these pathophysiological abnormalities have been studied in some cases with high-quality studies, whereas treatments for other pathophysiological abnormalities have not been well studied in many cases. There are some areas of more promising treatments specific for ASD including neurotransmitter abnormalities, particularly imbalances in glutamate and acetylcholine, sleep onset disorder (with behavioral therapy and melatonin), and metabolic abnormalities in folate, cobalamin, tetrahydrobiopterin, carnitine, and redox pathways. There is some evidence for treatments of epilepsy and seizures, mitochondrial and immune disorders, and gastrointestinal abnormalities, particularly imbalances in the enteric microbiome, but further clinical studies are needed in these areas to better define treatments specific to children with ASD. Clearly, there are some promising areas of ASD research that could lead to novel treatments that could become standard of care in the future, but more research is needed to better define subgroups of children with ASD who are affected by specific pathophysiological abnormalities and the optimal treatments for these abnormalities.
  • ... Such supplements include L-carnitine, coenzyme Q10, ubiquinol, B vitamin-containing multivitamins, ascorbic acid, α-tocopherol, and N-acetyl-Lcysteine [117,119]. Treatment with L-carnitine, an essential nutrient important for the fatty acid transport across the mitochondrial membrane, was shown to improve core and associated ASD symptoms in a number of controlled trials [119][120][121]. In one of these investigations, serum carnitine levels were found to correlate with cognitive and behavioral scores [121]. ...
    Article
    Full-text available
    Autism spectrum disorder (ASD), the fastest growing developmental disability in the United States, represents a group of neurodevelopmental disorders characterized by impaired social interaction and communication as well as restricted and repetitive behavior. The underlying cause of autism is unknown and therapy is currently limited to targeting behavioral abnormalities. Emerging studies suggest a link between mitochondrial dysfunction and ASD. Here, we review the evidence demonstrating this potential connection. We focus specifically on biochemical links, genetic-based associations, non-energy related mechanisms, and novel therapeutic strategies.
  • ... Also, in humans, carnitine administration was observed to increase significantly brain blood flow (Battistin et al. 1989, Postiglione et al. 1992. The replenishment of the carnitine that is reduced by hypoperfusion in ASD may be the reason for the reports of improved cognition in children diagnosed with an ASD treated with carnitine (Fahmy et al. 2013, Geier et al. 2011. ...
    Article
    Full-text available
    Cerebral hypoperfusion, or insufficient blood flow in the brain, occurs in many areas of the brain in patients diagnosed with autism spectrum disorder (ASD). Hypoperfusion was demonstrated in the brains of individuals with ASD when compared to normal healthy control brains either using positron emission tomography (PET) or single‑photon emission computed tomography (SPECT). The affected areas include, but are not limited to the: prefrontal, frontal, temporal, occipital, and parietal cortices; thalami; basal ganglia; cingulate cortex; caudate nucleus; the limbic system including the hippocampal area; putamen; substantia nigra; cerebellum; and associative cortices. Moreover, correlations between symptom scores and hypoperfusion in the brains of individuals diagnosed with an ASD were found indicating that the greater the autism symptom pathology, the more significant the cerebral hypoperfusion or vascular pathology in the brain. Evidence suggests that brain inflammation and vascular inflammation may explain a part of the hypoperfusion. There is also evidence of a lack of normal compensatory increase in blood flow when the subjects are challenged with a task. Some studies propose treatments that can address the hypoperfusion found among individuals diagnosed with an ASD, bringing symptom relief to some extent. This review will explore the evidence that indicates cerebral hypoperfusion in ASD, as well as the possible etiological aspects, complications, and treatments.
  • ... Similarly, the results of this study suggest that low levels of maternal carnitine may be correlated with the likelihood of having had a child later diagnosed with ASD. Previous studies have demonstrated that carnitine supplementation is bene cial for children with ASD (32)(33)(34). It is important to note that the results for this pilot study are for maternal levels post-pregnancy, so they are only suggestive of possible nutritional and metabolic differences during pregnancy. ...
    Preprint
    Full-text available
    Background: Previous research studies have demonstrated abnormalities in the metabolism of mothers of young children with autism. Method: Metabolic analysis was performed on blood samples from 30 mothers of young children with Autism Spectrum Disorder (ASD-M) and from 29 mothers of young typically-developing children (TD-M). Targeted metabolic analysis focusing on the folate one-carbon metabolism (FOCM) and the transsulfuration pathway (TS) as well as broad metabolic analysis were performed. Statistical analysis of the data involved both univariate and multivariate statistical methods. Results: Univariate analysis revealed significant differences in 5 metabolites from the folate one-carbon metabolism and the transsulfuration pathway and differences in an additional 48 metabolites identified by broad metabolic analysis, including lower levels of many carnitine-conjugated molecules. Multivariate analysis with leave one-out cross validation allowed classification of samples as belonging to one of the two groups with 93% sensitivity and 97% specificity with five metabolites. Furthermore, each of these five metabolites correlated with 8-15 other metabolites indicating that there are five clusters of correlated metabolites. In fact, all but 5 of the 50 metabolites with the highest area under the receiver operating characteristic curve were associated with the five identified groups. Many of the abnormalities appear linked to low levels of folate, vitamin B12, and carnitine-conjugated molecules. Conclusions: Mothers of children with ASD have many significantly different metabolite levels compared to mothers of typically developing children at 2-5 years after birth.
  • ... Many in vitro studies [22][23][24][25][26][27][28][29], and in vivo studies of animals [30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47] and humans [48][49][50][51][52][53][54][55][56][57][58][59] have reported different beneficial functions for carnitine. In the following, the main activities observed are reported. ...
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    Carnitine can be considered a conditionally essential nutrient for its importance in human physiology. This paper provides an updated picture of the main features of carnitine outlining its interest and possible use. Particular attention has been addressed to its beneficial properties, exploiting carnitine’s properties and possible use by considering the main in vitro, in animal, and human studies. Moreover, the main aspects of carnitine-based dietary supplements have been indicated and defined with reference to their possible beneficial health properties.
  • ... Additionally, a genetic abnormality in carnitine metabolism has been linked to ASD (129) and primary carnitine deficiency was reported to cause ASD in one case report (130). Three clinical trials have reported that carnitine supplementation improves symptoms in ASD (131)(132)(133). Thus, the importance of carnitine is being recognized in ASD and its deficiency is being acknowledged as a potential biomarker of a metabolic subgroup of ASD. ...
    Article
    Autism spectrum disorder (ASD) affects approximately 2% of children in the United States (US) yet its etiology is unclear and effective treatments are lacking. Therapeutic interventions are most effective if started early in life, yet diagnosis often remains delayed, partly because the diagnosis of ASD is based on identifying abnormal behaviors that may not emerge until the disorder is well established. Biomarkers that identify children at risk during the pre-symptomatic period, assist with early diagnosis, confirm behavioral observations, stratify patients into subgroups, and predict therapeutic response would be a great advance. Here we underwent a systematic review of the literature on ASD to identify promising biomarkers and rated the biomarkers in regards to a Level of Evidence and Grade of Recommendation using the Oxford Centre for Evidence-Based Medicine scale. Biomarkers identified by our review included physiological biomarkers that identify neuroimmune and metabolic abnormalities, neurological biomarkers including abnormalities in brain structure, function and neurophysiology, subtle behavioral biomarkers including atypical development of visual attention, genetic biomarkers and gastrointestinal biomarkers. Biomarkers of ASD may be found prior to birth and after diagnosis and some may predict response to specific treatments. Many promising biomarkers have been developed for ASD. However, many biomarkers are preliminary and need to be validated and their role in the diagnosis and treatment of ASD needs to be defined. It is likely that biomarkers will need to be combined to be effective to identify ASD early and guide treatment.
  • ... The second RCT evaluated the effect of higher dose of carnitine (100 mg/kg/day) or placebo in ASD patients for six months [25]. Significant improvements in autism symptoms based on the childhood autism rating scale (CARS) scores were reported but differently from the Geier et al. [22] study that showed no correlation between carnitine levels at the baseline and changes in CARS scores. ...
    Article
    Full-text available
    Carnitine is an amino acid derivative, which plays several important roles in human physiology, in the central nervous system, and for mitochondrial metabolism, in particular. Altered carnitine metabolic routes have been associated with a subgroup of patients with autism spectrum disorders (ASD) and could add to the pathophysiology associated with these disorders. We review the current evidence about the clinical effects of carnitine administration in ASD in both non-syndromic forms and ASD associated with genetic disorders. Two randomized clinical trials and one open-label prospective trial suggest that carnitine administration could be useful for treating symptoms in non-syndromic ASD. The effect of carnitine administration in ASD associated with genetic disorders is not conclusive because of a lack of clinical trials and objectives in ASD evaluation, but beneficial effects have also been reported for other comorbid disorders, such as intellectual disability and muscular strength. Side effects observed with a dose of 200 mg/kg/day consisted of gastro-intestinal symptoms and a strong, heavy skin odor. Doses of about 50–100 mg/kg/day are generally well tolerated. Further clinical trials with the identification of the subgroup of ASD patients that would benefit from carnitine administration are warranted.
  • ... Children with ASD, as a group, are deficient in Carnitine (45) with this deficiency potentially related to gastrointestinal symptom (46). Additionally, supplementing with Carnitine has been shown to improve core symptoms of ASD in two double-blind placebo controlled studies (47,48). (2) ASD features and ASD have been reported in patients with propionic acidemia (PA), a severe organic acidemia caused by propionic acid (PPA) accumulation due to propionyl-CoA carboxylase enzyme deficiency (49). ...
    Article
    Full-text available
    Autism spectrum disorder (ASD) is currently diagnosed according to behavioral criteria. Biomarkers that identify children with ASD could lead to more accurate and early diagnosis. ASD is a complex disorder with multifactorial and heterogeneous etiology supporting recognition of biomarkers that identify patient subsets. We investigated an easily testable blood metabolic profile associated with ASD diagnosis using high throughput analyses of samples extracted from dried blood spots (DBS). A targeted panel of 45 ASD analytes including acyl-carnitines and amino acids extracted from DBS was examined in 83 children with ASD (60 males; age 6.06 ± 3.58, range: 2–10 years) and 79 matched, neurotypical (NT) control children (57 males; age 6.8 ± 4.11 years, range 2.5–11 years). Based on their chronological ages, participants were divided in two groups: younger or older than 5 years. Two-sided T-tests were used to identify significant differences in measured metabolite levels between groups. Näive Bayes algorithm trained on the identified metabolites was used to profile children with ASD vs. NT controls. Of the 45 analyzed metabolites, nine (20%) were significantly increased in ASD patients including the amino acid citrulline and acyl-carnitines C2, C4DC/C5OH, C10, C12, C14:2, C16, C16:1, C18:1 (P: < 0.001). Näive Bayes algorithm using acyl-carnitine metabolites which were identified as significantly abnormal showed the highest performances for classifying ASD in children younger than 5 years (n: 42; mean age 3.26 ± 0.89) with 72.3% sensitivity (95% CI: 71.3;73.9), 72.1% specificity (95% CI: 71.2;72.9) and a diagnostic odds ratio 11.25 (95% CI: 9.47;17.7). Re-test analyses as a measure of validity showed an accuracy of 73% in children with ASD aged ≤ 5 years. This easily testable, non-invasive profile in DBS may support recognition of metabolic ASD individuals aged ≤ 5 years and represents a potential complementary tool to improve diagnosis at earlier stages of ASD development.
  • ... Core and associated ASD behaviors have been shown to improve with l-carnitine in two DBPC studies (n = 30, 30) [204,205]. Both studies used the CARS as the primary outcome measure and one study used an additional measures, the modified CGI. ...
    Article
    Full-text available
    Autism spectrum disorder is defined by two core symptoms: a deficit in social communication and the presence of repetitive behaviors and/or restricted interests. Currently, there is no US Food and Drug Administration-approved drug for these core symptoms. This article reviews the biological origins of the social function deficit associated with autism spectrum disorder and the drug therapies with the potential to treat this deficit. A review of the history of autism demonstrates that a deficit in social interaction has been the defining feature of the concept of autism from its conception. Abnormalities identified in early social skill development and an overview of the pathophysiology abnormalities associated with autism spectrum disorder are discussed as are the abnormalities in brain circuits associated with the social function deficit. Previous and ongoing clinical trials examining agents that have the potential to improve social deficits associated with autism spectrum disorder are discussed in detail. This discussion reveals that agents such as oxytocin and propranolol are particularly promising and undergoing active investigation, while other agents such as vasopressin agonists and antagonists are being activity investigated but have limited published evidence at this time. In addition, agents such as bumetanide and manipulation of the enteric microbiome using microbiota transfer therapy appear to have promising effects on core autism spectrum disorder symptoms including social function. Other pertinent issues associated with developing treatments in autism spectrum disorder, such as disease heterogeneity, high placebo response rates, trial design, and the most appropriate way of assessing effects on social skills (outcome measures), are also discussed.
  • ... Abnormalities in fatty acid metabolism may help account for the relative deficiency in carnitine associated with ASD [58,70], and the fact that mutations in the trimethyllysine hydroxylase epsilon (TMLHE) gene, the first enzyme in carnitine biosynthesis, is a risk factor for ASD [71]. In addition, children with ASD in general [72][73][74] and those with the TMLHE mutations specifically [75] benefit from supplementation with L-carnitine. Clearly, further research will be needed to better understand the significance of these fatty acid abnormalities in ASD and whether they are truly linked to disruptions in the enteric microbiome. ...
    Article
    Full-text available
    Autism spectrum disorder (ASD) affects ~ 2% of children in the United States. The etiology of ASD likely involves environmental factors triggering physiological abnormalities in genetically sensitive individuals. One of these major physiological abnormalities is mitochondrial dysfunction, which may affect a significant subset of children with ASD. Here we systematically review the literature on human studies of mitochondrial dysfunction related to ASD. Clinical aspects of mitochondrial dysfunction in ASD include unusual neurodevelopmental regression, especially if triggered by an inflammatory event, gastrointestinal symptoms, seizures, motor delays, fatigue and lethargy. Traditional biomarkers of mitochondrial disease are widely reported to be abnormal in ASD, but appear non-specific. Newer biomarkers include buccal cell enzymology, biomarkers of fatty acid metabolism, non-mitochondrial enzyme function, apoptosis markers and mitochondrial antibodies. Many genetic abnormalities are associated with mitochondrial dysfunction in ASD, including chromosomal abnormalities, mitochondrial DNA mutations and large-scale deletions, and mutations in both mitochondrial and non-mitochondrial nuclear genes. Mitochondrial dysfunction has been described in immune and buccal cells, fibroblasts, muscle and gastrointestinal tissue and the brains of individuals with ASD. Several environmental factors, including toxicants, microbiome metabolites and an oxidized microenvironment are shown to modulate mitochondrial function in ASD tissues. Investigations of treatments for mitochondrial dysfunction in ASD are promising but preliminary. The etiology of mitochondrial dysfunction and how to define it in ASD is currently unclear. However, preliminary evidence suggests that the mitochondria may be a fruitful target for treatment and prevention of ASD. Further research is needed to better understand the role of mitochondrial dysfunction in the pathophysiology of ASD.
  • ... Since the carnitine supplementation was primarily acetyl-L-carnitine (there was a small amount of L-carnitine in the vitamin/mineral supplement), this suggests inter-conversion between the two forms, as expected. However, the increase in plasma carnitine was only approximately 25%, which was less compared to another study [50] which used an equivalent dosage of L-carnitine and found a 70% increase in total carnitine in plasma, and another study using twice the dosage of L-carnitine found even higher increases in carnitine levels [51]. Comparing the results of the present study with the other two ASD studies suggests that L-carnitine may be better absorbed than acetyl-L-carnitine, and hence may be more effective. ...
    Article
    Full-text available
    This study involved a randomized, controlled, single-blind 12-month treatment study of a comprehensive nutritional and dietary intervention. Participants were 67 children and adults with autism spectrum disorder (ASD) ages 3–58 years from Arizona and 50 non-sibling neurotypical controls of similar age and gender. Treatment began with a special vitamin/mineral supplement, and additional treatments were added sequentially, including essential fatty acids, Epsom salt baths, carnitine, digestive enzymes, and a healthy gluten-free, casein-free, soy-free (HGCSF) diet. There was a significant improvement in nonverbal intellectual ability in the treatment group compared to the non-treatment group (+6.7 ± 11 IQ points vs. −0.6 ± 11 IQ points, p = 0.009) based on a blinded clinical assessment. Based on semi-blinded assessment, the treatment group, compared to the non-treatment group, had significantly greater improvement in autism symptoms and developmental age. The treatment group had significantly greater increases in EPA, DHA, carnitine, and vitamins A, B2, B5, B6, B12, folic acid, and Coenzyme Q10. The positive results of this study suggest that a comprehensive nutritional and dietary intervention is effective at improving nutritional status, non-verbal IQ, autism symptoms, and other symptoms in most individuals with ASD. Parents reported that the vitamin/mineral supplements, essential fatty acids, and HGCSF diet were the most beneficial.
  • Article
    Although there is no known efficacious pharmacotherapy for core symptoms of autism spectrum disorder (ASD), psychotropic medications are commonly prescribed for behavioral/emotional symptoms associated with ASD. We reviewed current evidence-based pharmacotherapy options and updates from recent noteworthy studies. Atypical antipsychotics, particularly risperidone and aripiprazole, are effective in reducing irritability, stereotypy and hyperactivity. Metabolic adverse events, including weight gain and dyslipidemia, are common. Methylphenidate is effective in reducing attention-deficit hyperactivity disorder (ADHD) symptoms. Atomoxetine and alpha-2 agonists appear effective in reducing ADHD symptoms. Selective serotonin reuptake inhibitors are not effective in improving repetitive behaviors in children with ASD, and frequently cause activating adverse events. Efficacy of antiepileptic drugs is inconclusive. Overall, efficacy and tolerability of pharmacotherapy in children with ASD are less favorable than data seen in typically developing children with similar symptoms. Newer agents, including glutamatergic agents and oxytocin, appear promising albeit with mixed results. Current evidence-based pharmacotherapy options in children with ASD are very limited, and many have substantial adverse events. Clinicians should use pharmacotherapy as a part of comprehensive treatment, and judiciously weigh risks and benefits. New pharmacotherapy options for core symptoms as well as co-occurring symptoms of ASD are in urgent need.
  • Article
    Full-text available
    Autism spectrum disorder (ASD) affects a significant number of individuals worldwide with the prevalence continuing to grow. It is becoming clear that a large subgroup of individuals with ASD demonstrate abnormalities in mitochondrial function as well as gastrointestinal (GI) symptoms. Interestingly, GI disturbances are common in individuals with mitochondrial disorders and have been reported to be highly prevalent in individuals with co-occurring ASD and mitochondrial disease. The majority of individuals with ASD and mitochondrial disorders do not manifest a primary genetic mutation, raising the possibility that their mitochondrial disorder is acquired or, at least, results from a combination of genetic susceptibility interacting with a wide range of environmental triggers. Mitochondria are very sensitive to both endogenous and exogenous environmental stressors such as toxicants, iatrogenic medications, immune activation, and metabolic disturbances. Many of these same environmental stressors have been associated with ASD, suggesting that the mitochondria could be the biological link between environmental stressors and neurometabolic abnormalities associated with ASD. This paper reviews the possible links between GI abnormalities, mitochondria, and ASD. First, we review the link between GI symptoms and abnormalities in mitochondrial function. Second, we review the evidence supporting the notion that environmental stressors linked to ASD can also adversely affect both mitochondria and GI function. Third, we review the evidence that enteric bacteria that are overrepresented in children with ASD, particularly Clostridia spp., produce short-chain fatty acid metabolites that are potentially toxic to the mitochondria. We provide an example of this gut-brain connection by highlighting the propionic acid rodent model of ASD and the clinical evidence that supports this animal model. Lastly, we discuss the potential therapeutic approaches that could be helpful for GI symptoms in ASD and mitochondrial disorders. To this end, this review aims to help better understand the underlying pathophysiology associated with ASD that may be related to concurrent mitochondrial and GI dysfunction.
  • Chapter
    Psychiatric disorders represent a large class of medical disorders with unclear etiologies and limited effective treatments. Mitochondrial dysfunction is particularly interesting as it can manifest a wide variety of symptoms including abnormalities in central nervous system functioning with focal neurological, cognitive, behavioral, and psychiatric symptoms. Evidence has started to accumulate that mitochondrial dysfunction plays a role in schizophrenia, major depression, bipolar disorder, personality/mood disorders, Alzheimer’s disease, and autism spectrum disorders. The prevalence of mitochondrial dysfunction in these disorders is not clear. Studies reporting laboratory testing for the identification of mitochondrial dysfunction and treatments in these disorders are generally lacking. Notably, the identification of mitochondrial dysfunction in psychiatric conditions could lead to the development of better medications and other treatments for these conditions that target specific metabolic abnormalities. Although the evidence for mitochondrial dysfunction in psychiatric disorders is increasing, additional studies are warranted.
  • Article
    Full-text available
    Despite the fact that seizures are commonly associated with autism spectrum disorder (ASD), the effectiveness of treatments for seizures has not been well studied in individuals with ASD. This manuscript reviews both traditional and novel treatments for seizures associated with ASD. Studies were selected by systematically searching major electronic databases and by a panel of experts that treat ASD individuals. Only a few anti-epileptic drugs (AEDs) have undergone carefully controlled trials in ASD, but these trials examined outcomes other than seizures. Several lines of evidence point to valproate, lamotrigine and levetiracetam as the most effective and tolerable AEDs for individuals with ASD. Limited evidence supports the use of traditional non-AED treatments, such as the ketogenic and modified Atkins diet, multiple subpial transections and immunomodulation and neurofeedback treatments. Although specific treatments may be more appropriate for specific genetic and metabolic syndromes associated with ASD and seizures, there are few studies which have documented the effectiveness of treatments for seizures for specific syndromes. Limited evidence supports L-carnitine, multivitamins and N-acetyl-L-cysteine in mitochondrial disease and dysfunction, folinic acid in cerebral folate abnormalities and early treatment with vigabatrin in tuberous sclerosis complex. Finally, there is limited evidence for a number of novel treatments, particularly magnesium with pyridoxine, omega-3 fatty acids, the gluten-free casein-free diet and transcranial magnetic simulation. Zinc and L-carnosine are potential novel treatments supported by basic research but not clinical studies. This review demonstrates the wide variety of treatments used to treat seizures in individuals with ASD as well as the striking lack of clinical trials performed to support the use these treatments. Additional studies concerning these treatments for controlling seizures in individuals with ASD are warranted.
  • Article
    The aim of this work is to evaluate the impact of butyl paraben (BP) in brain of the pups developed for mothers administered BP from early pregnancy till weaning and its effect on studying the behavior, brain neurotransmitters and brain derived neurotrophic factor BDNF via comparing the results with valproic acid (VA) autistic- rat model preparing by a single oral injection dose of VA (800 mg/kg b.wt) at the 12.5 day of gestation. Butyl paraben was orally and subcutaneously administered (200 mg/kg b.wt) to pregnant rats from gestation day 1 to lactation day 21. The offspring male rats were subjected at the last 3 days of lactation to morris water maze and three chamber sociability test then decapitated and brain was excised and dissected to the cortex, hippocampus, cerebellum, midbrain and pons for determination of norepinephrine, dopamine and serotonin (NE, DA and 5-HT) and cortex amino acids and whole brain BDNF. The results showed similar social and learning and memory behavioral deficits in VA rat model and the butyl paraben offspring in comparison with the controls. Also, a some similar alterations were observed in monoamine content, amino acids and BDNF factor in the autistic-like model and butyl paraben offspring in comparison with the controls. Notably, hippocampus and pons NE, midbrain DA, hippocampus and midbrain 5-HT, and frontal cortex GABA and asparagine. These data suggest that prenatal exposure to butyl paraben induced neuro-developmental disorders similar to some of the neurodevelopmental disorders observed in the VA model of autism.
  • Article
    Monitoring carnitine and acetylcarnitine levels in biological fluids is a powerful tool for diagnostic studies. Research has recently shown that the analysis of carnitine and related compounds in clinical samples can be accomplished by different analytical approaches. Because of the polar and ionic nature of the analytes and matrix complexity, accurate quantitation is a highly challenging task. Thus, sample processing factors, preparation/cleanup procedures, and chromatographic/ionization/detection parameters were evaluated. On the basis of the results obtained, a rapid, selective, sensitive method based on hydrophilic interaction liquid chromatography–tandem mass spectrometry for the analysis of carnitine and acetylcarnitine in serum and urine samples is proposed. The matrix effect was assessed. The proposed approach was validated, the limits of detection were in the nanomolar range, and carnitine and acetylcarnitine levels were found within the micromolar range in both types of sample. Figure Experimental workflow for the carnitine and acetylcarnitine determination in biological samples by HILIC-MS/MS
  • Pervasive developmental disorders and childhood psychosis Nelson textbook of pediatrics Philadelphia: WB Saunders
    • R Dalton
    • M A Forman
    • N W Boris
    Dalton, R., Forman, M. A., & Boris, N. W. (2004). Pervasive developmental disorders and childhood psychosis Nelson textbook of pediatrics, (17th ed.). Philadelphia: WB Saunders. (pp. 93–94).
  • National study of autism in Saudi Arabia King Abdulaziz City for Science and Technology Efficacy of carnitine in the treatment of children with attention-deficit hyperactivity disorder
    • A Talat
    • L J Van Oudheusden
    • H R Scholte
    Talat, A. (2008). National study of autism in Saudi Arabia King Abdulaziz City for Science and Technology. Van Oudheusden, L. J., & Scholte, H. R. (2002). Efficacy of carnitine in the treatment of children with attention-deficit hyperactivity disorder. Prostaglandins, Leukotrienes and Essential Fatty Acids, 67(1), 33–38.
  • Article
    Full-text available
    The current study examined the relationship between muscle strength, as measured by hand grip strength, and autism severity, as measured by the Childhood Autism Rating Scale (CARS). Thirty-seven (37) children with a diagnosis of autism spectrum disorder (ASD) were evaluated using the CARS and then tested for hand muscle strength using a hand grip dynamometer. Statistical analysis was then conducted to examine the relationship between autism severity and hand muscle strength. The model generated in the present study showed that the CARS score is a significant predictor of Max Hand Muscle Score after adjustment for age, race, gender, year of birth, and a history of prior chelation therapy. Evidence suggests that hand grip strength in children with ASD is related to the severity of the disorder. Further research is needed to determine the extent and consistency of the muscle weakness and possible treatments.
  • Article
    Over the past decade laboratories that test for metabolic disorders have introduced tandem mass spectrometry (MS/MS), which is more sensitive, specific, reliable, and comprehensive than traditional assays, into their newborn-screening programs. MS/MS is rapidly replacing these one-analysis, one-metabolite, one-disease classic screening techniques with a one-analysis, many-metabolites, many-diseases approach that also facilitates the ability to add new disorders to existing newborn-screening panels. During the past few years experts have authored many valuable articles describing various approaches to newborn metabolic screening by MS/MS. We attempted to document key developments in the introduction and validation of MS/MS screening for metabolic disorders. Our approach used the perspective of the metabolite and which diseases may be present from its detection rather than a more traditional approach of describing a disease and noting which metabolites are increased when it is present. This review cites important historical developments in the introduction and validation of MS/MS screening for metabolic disorders. It also offers a basic technical understanding of MS/MS as it is applied to multianalyte metabolic screening and explains why MS/MS is well suited for analysis of amino acids and acylcarnitines in dried filter-paper blood specimens. It also describes amino acids and acylcarnitines as they are detected and measured by MS/MS and their significance to the identification of specific amino acid, fatty acid, and organic acid disorders. Multianalyte technologies such as MS/MS are suitable for newborn screening and other mass screening programs because they improve the detection of many diseases in the current screening panel while enabling expansion to disorders that are now recognized as important and need to be identified in pediatric medicine.
  • Article
    The accumulation of carnitine was measured in cerebral cortex neurons isolated from adult rat brain. This process was found to be lowered by 40% after preincubation with ouabain and with SH-group reagents (N-ethylmaleimide and mersalyl). The initial velocity of carnitine transport was found to be inhibited by 4-aminobutyrate (GABA) in a competitive way (Ki = 20.9 ± 2.4 mm). However, of various inhibitors of GABA transporters, only nipecotic acid and very high concentrations of 1-[2-([(diphenylmethylene)amino]oxy)ethyl]-1,2,5,6-tetrahydro-3-pyridinecarboxylic acid hydrochloride (NO-711) acid decreased carnitine accumulation while betaine, taurine and β-alanine had no effect. The GABA transporters expressed in Xenopus laevis oocytes did not transport carnitine. Moreover, carnitine was not observed to diminish the accumulation of GABA in cerebral cortex neurons, which further excluded a possible involvement of the GABA transporter GAT1 in the process of carnitine accumulation, despite the expression of this protein in the cells under study. The absence of carnitine transporter OCTN2 in rat cerebral cortex neurons (K. A. Nałecz, D. Dymna, J. E. Mroczkowska, A. Broër, S. Broër, M. J. Nałecz and R. Cecchelli, unpublished results), together with the insensitivity of carnitine accumulation towards betaines, implies that a novel transporting protein is present in these cells.
  • Article
    Full-text available
    L-carnitine was proposed as a potential treatment for patients diagnosed with an autism spectrum disorder to improve mitochondrial dysfunction, but no prior randomized controlled trials have been conducted. Thirty subjects diagnosed with an ASD were randomly assigned to receive a standardized regimen (50 mg L-carnitine/kg bodyweight/day) of liquid L-carnitine (n=19) or placebo (n=11) for 3-months. Measures included changes in professionally completed Childhood Autism Rating Scale (CARS), hand muscle testing, and modified clinical global impression (CGI) forms; parent completed Autism Treatment Evaluation Checklist (ATEC), treatment adherence measurement (TAM), frequency and intensity of side effect rating (FISER)/global rating of side effect burden (GRSEB)/patient report of incidence of side effects (PRISE) forms; and lab testing. Significant improvements were observed in CARS (-2.03, 95% CI=-3.7 to -0.31), CGI (-0.69, 95% CI=-1.1 to -0.06), and ATEC scores. Significant correlations between changes in serum free-carnitine levels and positive clinical changes were observed for hand muscle strength (R2=0.23, P=0.046), cognitive scores (R2=0.27, P=0.019), and CARS scores (R2=0.20, P=0.047). Study subjects were protocol-compliant (average adherence was >85%) and generally well-tolerated the L-carnitine therapy given. L-carnitine therapy (50 mg/kilogram-bodyweight/day) administered for 3-months significantly improved several clinical measurements of ASD severity, but subsequent studies are recommended.
  • Article
    Full-text available
    A comprehensive literature search was performed to collate evidence of mitochondrial dysfunction in autism spectrum disorders (ASDs) with two primary objectives. First, features of mitochondrial dysfunction in the general population of children with ASD were identified. Second, characteristics of mitochondrial dysfunction in children with ASD and concomitant mitochondrial disease (MD) were compared with published literature of two general populations: ASD children without MD, and non-ASD children with MD. The prevalence of MD in the general population of ASD was 5.0% (95% confidence interval 3.2, 6.9%), much higher than found in the general population (≈ 0.01%). The prevalence of abnormal biomarker values of mitochondrial dysfunction was high in ASD, much higher than the prevalence of MD. Variances and mean values of many mitochondrial biomarkers (lactate, pyruvate, carnitine and ubiquinone) were significantly different between ASD and controls. Some markers correlated with ASD severity. Neuroimaging, in vitro and post-mortem brain studies were consistent with an elevated prevalence of mitochondrial dysfunction in ASD. Taken together, these findings suggest children with ASD have a spectrum of mitochondrial dysfunction of differing severity. Eighteen publications representing a total of 112 children with ASD and MD (ASD/MD) were identified. The prevalence of developmental regression (52%), seizures (41%), motor delay (51%), gastrointestinal abnormalities (74%), female gender (39%), and elevated lactate (78%) and pyruvate (45%) was significantly higher in ASD/MD compared with the general ASD population. The prevalence of many of these abnormalities was similar to the general population of children with MD, suggesting that ASD/MD represents a distinct subgroup of children with MD. Most ASD/MD cases (79%) were not associated with genetic abnormalities, raising the possibility of secondary mitochondrial dysfunction. Treatment studies for ASD/MD were limited, although improvements were noted in some studies with carnitine, co-enzyme Q10 and B-vitamins. Many studies suffered from limitations, including small sample sizes, referral or publication biases, and variability in protocols for selecting children for MD workup, collecting mitochondrial biomarkers and defining MD. Overall, this evidence supports the notion that mitochondrial dysfunction is associated with ASD. Additional studies are needed to further define the role of mitochondrial dysfunction in ASD.
  • Article
    This study investigated the childhood autism rating scale (CARS) as a tool for ASD diagnoses for 2-year-old (n = 376) and 4-year-old (n = 230) children referred for possible autism. The cut-off score to distinguish autistic disorder from PDD-NOS was 32 in the 2-year-old sample (consistent with Lord in J Child Psychol Psychiatry Allied Discipl, 36, 1365-1382, 1995), and 30 in the 4-year-old sample, with good sensitivity and specificity at both ages. The cut-off score to distinguish ASD from non-ASD at both ages was 25.5, with good sensitivity and specificity. Results confirm the utility of the CARS in distinguishing autistic disorder from PDD-NOS, and distinguishing ASD from other developmental disorders and typical development and suggest that an ASD cutoff around 25, which is in common clinical use, is valid.
  • Article
    Autism is a neurological disorder that manifests as noticeable behavioral and developmental abnormalities predominantly in males between the ages of 2 and 10. Although the genetics, biochemistry and neuropathology of this disease have been extensively studied, underlying causal factors to this disease have remained elusive. Using a longitudinal trial design in which three plasma samples were collected from 15 autistic and 12 non-autistic age-matched controls over the course of 1 year, universal and unambiguous alterations in lipid metabolism were observed. Biomarkers of fatty acid elongation and desaturation (poly-unsaturated long chain fatty acids (PUFA) and/or saturated very long chain fatty acids (VLCFA)-containing ethanolamine phospholipids) were statistically elevated in all autistic subjects. In all 8 of the affected/non-affected sibling pairs, the affected sibling had higher levels of these biomarkers than the unaffected sibling. Exposure of neurons, astrocytes and hepatocytes in vitro to elevated extracellular glutamate levels resulted in lipid biomarker changes indistinguishable from those observed in autistic subjects. Glutamate stress also resulted in in vitro decreased levels of reduced glutathione (GSH), methionine and cysteine, in a similar way to the decreases we observed in autism plasma. Impaired mitochondrial fatty acid oxidation, elevated plasma VLCFAs, and glutamate toxicity as putative causal factors in the biochemistry, neuropathology, and gender bias in autism are discussed.
  • Article
    Full-text available
    Classical mitochondrial diseases occur in a subset of individuals with autism and are usually caused by genetic anomalies or mitochondrial respiratory pathway deficits. However, in many cases of autism, there is evidence of mitochondrial dysfunction (MtD) without the classic features associated with mitochondrial disease. MtD appears to be more common in autism and presents with less severe signs and symptoms. It is not associated with discernable mitochondrial pathology in muscle biopsy specimens despite objective evidence of lowered mitochondrial functioning. Exposure to environ-mental toxins is the likely etiology for MtD in autism. This dysfunction then contributes to a number of diagnostic symptoms and comorbidities observed in autism including: cognitive impairment, language deficits, abnormal energy metabolism, chronic gastrointestinal problems, abnormalities in fatty acid oxidation, and increased oxidative stress. MtD and oxidative stress may also explain the high male to female ratio found in autism due to increased male vulnerability to these dysfunctions. Biomarkers for mitochondrial dysfunction have been identified, but seem widely under-utilized despite available therapeutic interventions. Nutritional supplementation to decrease oxidative stress along with factors to improve reduced glutathione, as well as hyperbaric oxygen therapy (HBOT) represent supported and rationale approaches. The underlying pathophysiology and autistic symptoms of affected individuals would be expected to either improve or cease worsening once effective treatment for MtD is implemented.
  • Article
    Full-text available
    While evidence points to a multigenic etiology of most autism, the pathophysiology of the disorder has yet to be defined and the underlying genes and biochemical pathways they subserve remain unknown. Autism is considered to be influenced by a combination of various genetic, environmental and immunological factors; more recently, evidence has suggested that increased vulnerability to oxidative stress may be involved in the etiology of this multifactorial disorder. Furthermore, recent studies have pointed to a subset of autism associated with the biochemical endophenotype of mitochondrial energy deficiency, identified as a subtle impairment in fat and carbohydrate oxidation. This phenotype is similar, but more subtle than those seen in classic mitochondrial defects. In some cases the beginnings of the genetic underpinnings of these mitochondrial defects are emerging, such as mild mitochondrial dysfunction and secondary carnitine deficiency observed in the subset of autistic patients with an inverted duplication of chromosome 15q11-q13. In addition, rare cases of familial autism associated with sudden infant death syndrome (SIDS) or associated with abnormalities in cellular calcium homeostasis, such as malignant hyperthermia or cardiac arrhythmia, are beginning to emerge. Such special cases suggest that the pathophysiology of autism may comprise pathways that are directly or indirectly involved in mitochondrial energy production and to further probe this connection three new avenues seem worthy of exploration: 1) metabolomic clinical studies provoking controlled aerobic exercise stress to expand the biochemical phenotype, 2) high-throughput expression arrays to directly survey activity of the genes underlying these biochemical pathways and 3) model systems, either based upon neuronal stem cells or model genetic organisms, to discover novel genetic and environmental inputs into these pathways.
  • Article
    We report the application of tandem mass spectrometry to prospective newborn screening for medium-chain acyl-CoA dehydrogenase (MCAD) deficiency. MCAD deficiency is diagnosed from dried blood spots on filter paper cards from newborns on the basis of the increase of medium chain length acylcarnitines identified by isotope dilution mass spectrometry methods. A robust and accurate semiautomated method for the analysis of medium chain length acylcarnitines as their butyl esters was developed and validated. Quantitative data from the analyses of 113 randomly collected filter paper blood spots from healthy newborns showed low concentrations of medium chain length acylcarnitines such as octanoylcarnitine. The maximum concentration of octanoylcarnitine was 0.22 mumol/L, with the majority being at or below the detection limit. In all 16 blood spots from newborns with confirmed MCAD deficiency, octanoylcarnitine was highly increased [median 8.4 mumol/L (range 3.1-28.3 mumol/L)], allowing easy detection. The concentration of octanoylcarnitine was significantly higher in these 16 newborns (< 3 days of age) than in 16 older patients (ages 8 days to 7 years) with MCAD deficiency (median 1.57 mumol/L, range 0.33-4.4). The combined experience of prospective newborn screening in Pennsylvania and North Carolina has shown a disease frequency for MCAD deficiency of 1 in 17,706. No false-positive and no known false-negative results have been found. A validated method now exists for prospective newborn screening for MCAD deficiency.
  • Article
    The objective of this study was to assess age- and sex-related differences of serum carnitine in a Japanese population. Fasting blood samples were obtained from 296 Japanese males and 258 females 0 to 65 years of age. Serum free carnitine and acylcarnitine levels were determined by a fluorometric method using carnitine dehydrogenase. Of these, serum samples from 20 males 10 to 20 years of age and 23 females 40 to 60 years of age were assayed for testosterone and estradiol, respectively. Fasting blood samples and 24-hour urine samples were also obtained from 20 males and 23 females 0 to 50 years of age for the assessment of renal carnitine reabsorption. Serum free carnitine increased with age in children of both sexes, reaching adult value between 15 to 20 years of age in males and between 2 to 10 years of age in females. The mean free carnitine in males (50.3 +/- 7.5 mumol/L) was significantly higher than that in female (41.2 +/- 7.5 mumol/L) between 15-50 years of age (p < 0.05). Serum acylcarnitine remained constant (14.7 +/- 3.3 mumol/L) in each subject of various ages in both sexes. A significant negative correlation was observed between serum free carnitine and estradiol in females (r = -0.55, p < 0.01), but was not observed between serum free carnitine and testosterone in males (r = 0.015). The percent renal reabsorption of free carnitine showed no age-related and sex-related differences. Serum free carnitine level is related to age and sex, while serum acylcarnitine level remains constant. Our findings suggest that estrogen decreases serum free carnitine and causes sex-related differences.
  • Article
    Autism is a developmental disorder characterized by disturbance in language, perception and socialization. A variety of biochemical, anatomical and neuroradiographical studies imply a disturbance of brain energy metabolism in autistic patients. The underlying etiology of a disturbed bioenergetic metabolism in autism is unknown. A likely etiological possibility may involve mitochondrial dysfunction with concomitant defects in neuronal oxidative phosphorylation within the central nervous system. This hypothesis is supported by a frequent association of lactic acidosis and carnitine deficiency in autistic patients. Mitochondria are vulnerable to a wide array of endogenous and exogenous factors which appear to be linked by excessive nitric oxide production. Strategies to augment mitochondrial function, either by decreasing production of endogenous toxic metabolites, reducing nitric oxide production, or stimulating mitochondrial enzyme activity may be beneficial in the treatment of autism.
  • Article
    Rett syndrome is a severe neurodevelopmental disorder of unknown etiology, occurring almost exclusively in female patients. The etiology and functional significance of plasma carnitine deficiency seen in some patients with Rett syndrome is unknown. To investigate whether L-carnitine might be of benefit in Rett syndrome, a randomized, placebo-controlled, double-blind crossover trial of L-carnitine has been completed in 35 subjects. Eight-week treatment phases were completed for both a placebo and L-carnitine. Outcome was measured by parents/caregivers and at medical follow-up using three established tools: the Rett Syndrome Motor Behavioral Assessment, the Hand Apraxia Scale, and the Patient Well-Being Index. Analysis comparing change between baseline and week 8 of treatment for L-carnitine and the placebo showed that both parents/caregivers and medical follow-up detected improvements in the subjects' well-being. In addition, medical review showed an improvement on the Hand Apraxia Scale for a higher proportion of girls on L-carnitine. Identification of predictors of clinical improvement has been limited by the power of the study. These findings suggest that L-carnitine is of benefit in some patients with Rett syndrome. While L-carnitine did not lead to major functional changes in ability, the type of changes reported could still have a substantial impact on the girls and their families. Information is still needed, however, to determine if only subgroups of girls with the disorder are responsive to L-carnitine and the appropriate duration of therapy.
  • Article
    ++Electrospray-tandem mass spectrometry represents a powerful method for detection of inborn errors of fatty acid metabolism. In the present study, it was used to examine neonatal carnitine metabolism, which reflects fatty acid metabolism. In 70 healthy neonates, blood samples were taken from the umbilical cord and by heel-stick puncture in full-term neonates on postnatal d 5. Cord blood specimens were also obtained from 15 preterm and 10 small-for-gestational-age infants. Acylcarnitine concentrations were measured in dried blood spots by electrospray tandem mass spectrometry. Compared with cord blood, the levels of nearly all acylcarnitine species were significantly higher on the postnatal d 5, whereas free carnitine remained unchanged. Total acylcarnitine/free carnitine-ratio increased, whereas the free carnitine/total carnitine-ratio (0.54 +/- 0.05; p < 0.01) further decreased. A reduced availability of free carnitine in the early neonatal period may affect fatty acid oxidation and thus be of potential pathophysiological relevance under conditions with higher energy demands, e.g. in sepsis. Cord blood concentrations of free carnitine, total carnitine, and total acylcarnitines were strongly related to birth weight (p < 0.01). Lower umbilical artery pH, i.e. mild hypoxia, caused accumulation of mainly long-chain acylcarnitines. This implicates that long-chain acylcarnitines could serve as a parameter of perinatal asphyxia.
  • Article
    The accumulation of carnitine was measured in cerebral cortex neurons isolated from adult rat brain. This process was found to be lowered by 40% after preincubation with ouabain and with SH-group reagents (N-ethylmaleimide and mersalyl). The initial velocity of carnitine transport was found to be inhibited by 4-aminobutyrate (GABA) in a competitive way (Ki = 20.9 +/- 2.4 mM). However, of various inhibitors of GABA transporters, only nipecotic acid and very high concentrations of 1-[2-([(diphenylmethylene)amino]oxy)ethyl]-1,2,5,6-tetrahydro-3-pyridinecarboxylic acid hydrochloride (NO-711) acid decreased carnitine accumulation while betaine, taurine and beta-alanine had no effect. The GABA transporters expressed in Xenopus laevis oocytes did not transport carnitine. Moreover, carnitine was not observed to diminish the accumulation of GABA in cerebral cortex neurons, which further excluded a possible involvement of the GABA transporter GAT1 in the process of carnitine accumulation, despite the expression of this protein in the cells under study. The absence of carnitine transporter OCTN2 in rat cerebral cortex neurons (K. A. Nałecz, D. Dymna, J. E. Mroczkowska, A. Broër, S. Broër, M. J. Nałecz and R. Cecchelli, unpublished results), together with the insensitivity of carnitine accumulation towards betaines, implies that a novel transporting protein is present in these cells.
  • Article
    Full-text available
    Autism is a pervasive developmental disorder. The incidence rate and other related epidemiological characteristics of the Israeli population are not available. To assess the incidence rate of autism in the Haifa area and to compare family characteristics with previous reports from other countries. We approached facilities in the Haifa area that are involved with the diagnosis and treatment of autism. The study group comprised children born between 1989 and 1993. Records of the children were scrutinized and 69% of the mothers were interviewed. Live-birth cohorts of the same years were employed for incidence computation. An incidence rate of 1/1,000 was derived. Male to female ratio was 4.2:1. Pregnancy and perinatal periods were mostly uneventful. A low prevalence of developmental and emotional morbidity was reported for family members. The epidemiological characteristics found in the Haifa area are similar to those reported from non-Israeli communities. This finding supports an underlying biological mechanism for this disorder. These data can be used for future trend analyses in Israel.
  • Article
    Treatment strategies in Rett syndrome so far have been essentially symptomatic and supportive. In order to establish the medium-term effects of L-carnitine, an open label trial was performed in a cohort of 21 Rett syndrome females, with a control group of 62 Rett syndrome females of a similar age, for a 6-month period. Compared with the Rett syndrome controls, treatment with L-carnitine led to significant improvements in sleep efficiency (P=0.027), especially in the subjects with a baseline sleep efficiency less than 90%, energy level (P<0.005) and communication skills (P=0.004). There was no significant difference in the subject's level of physical activity, hand function or in the quality of life of the subject's parents. In addition, before and after comparisons of the treatment group showed improvements in expressive speech (P=0.011). Treatment with L-carnitine seems to be of significant benefit in a subgroup of girls with Rett syndrome. In these girls, small but discernible improvements may be of considerable importance to their parents and carers.
  • Article
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    L-Carnitine (L-C) is a naturally occurring quaternary ammonium compound endogenous in all mammalian species and is a vital cofactor for the mitochondrial oxidation of fatty acids. Fatty acids are utilized as an energy substrate in all tissues, and although glucose is the main energetic substrate in adult brain, fatty acids have also been shown to be utilized by brain as an energy substrate. L-C also participates in the control of the mitochondrial acyl-CoA/CoA ratio, peroxisomal oxidation of fatty acids, and the production of ketone bodies. Due to their intrinsic interaction with the bioenergetic processes, they play an important role in diseases associated with metabolic compromise, especially mitochondrial-related disorders. A deficiency of carnitine is known to have major deleterious effects on the CNS. Several syndromes of secondary carnitine deficiency have been described that may result from defects in intermediary metabolism and alterations principally involving mitochondrial oxidative pathways. Mitochondrial superoxide formation resulting from disturbed electron transfer within the respiratory chain may affect the activities of respiratory chain complexes I, II, III, IV, and V and underlie some CNS pathologies. This mitochondrial dysfunction may be ameliorated by L-C and its esters. In addition to its metabolic role, L-C and its esters such as acetyl-L-carnitine (ALC) poses unique neuroprotective, neuromodulatory, and neurotrophic properties which may play an important role in counteracting various disease processes. Neural dysfunction and metabolic imbalances underlie many diseases, and the inclusion of metabolic modifiers may provide an alternative and early intervention approach, which may limit further developmental damage, cognitive loss, and improve long-term therapeutic outcomes. The neurophysiological and neuroprotective actions of L-C and ALC on cellular processes in the central and peripheral nervous system show such effects. Indeed, many studies have shown improvement in processes, such as memory and learning, and are discussed in this review.
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    Autism spectrum disorder (ASD) is a spectrum of behavioral anomalies characterized by impaired social interaction and communication, often accompanied by repetitive and stereotyped behavior. The condition manifests within the first 3 years of life and persists into adulthood. There are numerous hypotheses regarding the etiology and pathology of ASD, including a suggested role for immune dysfunction. However, to date, the evidence for involvement of the immune system in autism has been inconclusive. While immune system abnormalities have been reported in children with autistic disorder, there is little consensus regarding the nature of these differences which include both enhanced autoimmunity and reduced immune function. In this review, we discuss current findings with respect to immune function and the spectrum of autoimmune phenomena described in children with ASD.
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    A random retrospective chart review was conducted to document serum carnitine levels on 100 children with autism. Concurrently drawn serum pyruvate, lactate, ammonia, and alanine levels were also available in many of these children. Values of free and total carnitine (p < 0.001), and pyruvate (p = 0.006) were significantly reduced while ammonia and alanine levels were considerably elevated (p < 0.001) in our autistic subjects. The relative carnitine deficiency in these patients, accompanied by slight elevations in lactate and significant elevations in alanine and ammonia levels, is suggestive of mild mitochondrial dysfunction. It is hypothesized that a mitochondrial defect may be the origin of the carnitine deficiency in these autistic children.
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    The acylcarnitine profiles obtained from dried blood spots on "Guthrie cards" have been widely used for the diagnosis and follow-up of children suspected of carrying an inherited error of metabolism, but little attention has been paid to potential age-related variations in the reference values. In this study, we evaluated the variations in free carnitine and acylcarnitine concentrations with age, as measured by tandem mass spectrometry. Filter-paper blood spots were collected from 433 healthy individuals over a period of 17 months. Eight age groups were defined: cord blood, 3-6 days (control group), 15-55 days, 2-18 months, 19-59 months, 5-10 years, 11-17 years, and 18-54 years. Free carnitine and acylcarnitines were measured for each individual. Mean values were calculated for each age group and compared with those for the control group. Free carnitine was significantly higher in older children than in newborns (P <0.05), but the concentrations of several acylcarnitines tended to be significantly lower in cord blood and in groups of older children than in the control group. Only minor sex-related differences were observed. Although the risk of underdiagnosis of fatty acid oxidation disorders with the use of newborn values as reference can be considered as small, in some circumstances the use of age-related reference values may have a potential impact on the diagnosis and management of inherited errors of metabolism.
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