Smell Identification Function in Children with Attention Deficit Hyperactivity Disorder

Research Center for Psychiatry and Behavioral Sciences, Department of Psychiatry, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran.
Psychiatry investigation (Impact Factor: 1.28). 06/2012; 9(2):150-3. DOI: 10.4306/pi.2012.9.2.150
Source: PubMed


Deficits in olfactory function are common features in neurodegenerative and neuropsychiatric disorders. Olfactory processing is related to dopamine metabolism and orbitofrontal cortex functioning, both known to be involved in the neurobiology of ADHD. Some investigations suggested alterations in olfactory processing (identification and detection threshold) in patients with ADHD. Despite increasing knowledge, controversy about this topic still exists regarding children with ADHD. This study was conducted to help elucidate some of this controversy.
50 participants (8-15 years, mean=10.70±1.77) with ADHD were compared to 50 controls. The two groups were well matched for age, gender and Mean School Scores (MSS). We assessed odor identification and threshold through a smell test composed of two tests of identification and detection threshold. Odor detection threshold was assessed with the odorant phenyl ethyl alcohol solved in propylene glycol using a single staircase method. Odor identification was assessed with chemical essences of five common odorants.
The mean Sensory Identification Score for children with ADHD and the control groups were 3.76 (1.06) and 4.46 (0.76), respectively (p<0.001). The mean for Sensory Threshold Score for ADHD and control group was 6.4 (3.35) and 9.75 (2.16), respectively (p<0.001).
This study replicated altered olfactory performance in ADHD. Substantial olfactory deficits across the two domains of identification and detection threshold are observed in children with ADHD. These deficits do not seem to be a result of olfactory task difficulty and are not influenced by age, gender and MSS. Further studies are required to investigate whether olfactory function can be used as a biological marker for early diagnosis, treatment and prognosis of ADHD.

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Available from: Ahmad Ghanizadeh
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    • "include Alzheimer's disease, Parkinson's disease, Huntington's chorea, schizophrenia, first-episode psychosis, depression, posttraumatic stress disorder, autism, and attention-deficit/hyperactivity disorder (Atanasova et al., 2006; Brewer et al., 2006, 2008; Hawkes and Doty, 2009; Zucco and Bollini, 2011; Ghanizadeh et al., 2012). However, until today, a few studies have examined olfactory identification ability in patients with OCD (Goldberg et al., 1991; Locatelli et al., 1996; Barnett et al., 1999; Fenger et al., 2005; Segalàs et al., 2011). "
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    ABSTRACT: Olfactory identification ability implicates the integrity of the orbitofrontal cortex (OFC). The fronto-striatal circuits including the OFC have been involved in the neuropathology of Obsessive Compulsive Disorder (OCD). However, only a few studies have examined olfactory function in patients with OCD. The Brief Smell Identification Test (B-SIT) and tests from the Cambridge Neuropsychological Automated Battery (CANTAB) were administered to 25 patients with OCD and to 21 healthy matched controls. OCD patients showed a significant impairment in olfactory identification ability as well as widely distributed cognitive deficits in visual memory, executive functions, attention, and response inhibition. The degree of behavioural impairment on motor impulsivity (prolonged response inhibition Stop-Signal Reaction Time) strongly correlated with the B-SIT score. Our study is the first to indicate a shared OFC pathological neural substrate underlying olfactory identification impairment, impulsivity, and OCD. Deficits in visual memory, executive functions and attention further indicate that regions outside of the orbitofronto-striatal loop may be involved in this disorder. Such results may help delineate the clinical complexity of OCD and support more targeted investigations and interventions. In this regard, research on the potential diagnostic utility of olfactory identification deficits in the assessment of OCD would certainly be useful.
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    ABSTRACT: Objective: To evaluate the olfactory and psychophysical performances in a 13-yearold boy with intellectual disability and severe hypoplasia of the corpus callosum and of the olfactory bulbs, compared to controls. Methods: The Sniffin’ Sticks Identification Test was administered to the patient and to a patient control child with cognitive delay, with the same mental (5 years) and chronological age, but normal brain magnetic resonance image. Two typically developing control participants, aged 13 and 5, were also evaluated. Psychophysical tests were performed during the olfactory assessment by smart portable sensors. Results: A significant decrease in olfactory function and a different psychophysical response to stimuli were observed in the patient compared to control participants, suggesting absence of ‘odorous stress’. A higher olfactory score but a similar psychophysical trend was found in the patient control with cognitive delay, while the two other control participants showed a selective increase of the anxiety state depending on the odour presented. Conclusions: Olfactory dysfunction is reported in children with neurodevelopmental disabilities. Low-cost, portable devices to assess olfactory function are proposed for use with children with intellectual disability. Stress monitoring by unobtrusive platforms provides discriminant information in this subset, as compared to controls.
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    ABSTRACT: Objective: Attention Deficit/Hyperactivity Disorder (ADHD) is diagnosed using Diagnostic and Statistical Manual of Mental Disorders criteria, neuropsychological testing, examinations, and parent, teacher, and self-evaluation forms. Diagnosing of ADHD depends on clinical evaluation, others are auxilary methods. No biological, electrophysio-logical, or neuroimaging markers currently exist to diagnose ADHD. Many studies about the biological markers for diagnosing ADHD have been conducted. Olfactory and gustatory dysfunctions have not been well studied in ADHD for this purpose. For this reason this study aimed to evaluate both the olfactory and gustatory functions of children with ADHD. Methods: A total of 34 children with ADHD and a control group containing 31 children aged 6-15 years participated in the study. We used the Sniffin’ Sticks odor tests and propylthiouracil (PROP) bitterness sensitivity test to examine odor and taste sensitivity, respectively. Results: We found no statistically significant differences between the ADHD and control groups in terms of odor sensitivity, odor discrimination, and odor identification. A statistically significant difference between groups was observed in PROP scores. Children in the ADHD group were less sensitive to bitterness than the control group. Conclusion: PROP bitterness test is in an advantageous state for being a marker in advanced years due to ease of use, independence of age and very short test period. As a result, in our study, it is concluded that PROP bitterness test may be a biological marker for ADHD diagnosis, however, further studies are needed. © 2015, Cukurova University, Faculty of Medicine. All rights reserved.
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