This study evaluated the phenomenon of autistic regression using population-based data. The sample comprised 285 children who met the autism spectrum disorder (ASD) case definition within an ongoing surveillance program. Results indicated that children with a previously documented ASD diagnosis had higher rates of autistic regression than children who met the ASD surveillance definition but did not have a clearly documented ASD diagnosis in their records (17-26 percent of surveillance cases). Most children regressed around 24 months of age and boys were more likely to have documented regression than girls. Half of the children with regression had developmental concerns noted prior to the loss of skills. Moreover, children with autistic regression were more likely to show certain associated features, including cognitive impairment.These data indicate that some children with ASD experience a loss of skills in the first few years of life and may have a unique symptom profile.
"By far the most provocative evidence for a putative environmental postnatal precipitating factor in autism is the unexplained regression or stagnation of behavior and language development at 15–30 months reported by some third of parents of toddlers [Kurita, 1985; Rogers, 2004; Wilson, Djukic, Shinnar, Dharmani, & Rapin, 2003]. There is sparse information about sex ratio among these children, although one study reports that the proportion of boys was marginally higher (90%) in those who regressed than in those who did not (84%) [Wiggins, Rice, & Baio, 2009]. If regression is indeed more prevalent in boys and is in some way environmentally–influenced, which has not been documented, it might indicate that some genetically susceptible boys are more vulnerable than girls to some environmental factors such as common-place potentially triggering events like infections or immunologic factors. "
[Show abstract][Hide abstract] ABSTRACT: We offer a neurobiologic theory based on animal work that helps account for the conspicuous male predominance in autism spectrum disorders (ASD). In young male animals, testosterone (TST) binds to androgen receptors (AR) in brainstem neurons responsible for enhancing brain arousal. As a consequence, arousal-related neurotransmitters bombard the amygdala hypersensitized by TST acting though AR. Arousal-related inputs are known to prime amygdaloid mechanisms for fear and anxiety, with resultant social avoidance. We hypothesize that similar mechanisms contribute to autism's male predominance and to its defining impaired social skills. The theory rests on two key interacting factors: the molecular effects of TST in genetically vulnerable boys in combination with environmental stresses they experienced in utero, neonatally, or during the first years. We postulate that higher TST levels and, therefore, higher amounts of arousal-related inputs to the amygdala sensitize these genetically vulnerable male infants to very early stresses. In sharp contrast to boys, girls not only do not have high levels of TST-facilitated arousal-causing inputs to the amygdala but they also enjoy the protection afforded by estrogenic hormones, oxytocin, and the oxytocin receptor. This theory suggests that novel technologies applied to the molecular endocrinology of TST's actions through AR will offer new avenues of enquiry into ASD. Since the high male preponderance in autism is important yet understudied, we offer our theory, which is based on detailed neurobehavioral research with animals, to stimulate basic and clinical research in animals and humans and hopefully help develop novel more effective medical treatments for autism.
Autism Research 06/2011; 4(3):163-76. DOI:10.1002/aur.191 · 4.33 Impact Factor
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