Perinatal Immune Activation and Risk of Autism

Abstract

He could fit in the palms of both hands, seemed to look at you beseechingly while you rushed to thread a vein and snake a tube down a tiny nostril of this 24 week preemie. Already exposed to the prenatal stress that culminated in premature delivery, he has been further exposed to the stress associated with the separation from his mother and multiple medical interventions. Like other premature babies, he is more vulnerable to invasive infections from bacteria and viruses; moreover, the delayed development of his gut-blood-brain barriers could expose him to potential neurotoxins. Such infants are up to 4 times more likely to develop autism. If their mothers had allergies, mastocytosis or an autoimmune disease, this risk almost doubles. Autism Spectrum Disorders (ASD) are pervasive developmental disorders that include Autistic Disorder and Asperger’s Disorder, although Pervasive Developmental Disorder-Not Otherwise Specified (PDD-NOS) is frequently included (Johnson & Myers, 2007). ASD are characterized by variable deficits in social skills, stereotypic behaviors, and a wide range of behavioral and learning problems. ASD manifest during early childhood and at least 30% present with sudden clinical regression of development around 3 years of age (Matson J.L. & Kozlowski A.M., 2010; Zappella, 2010). Over the last 20 years, there has been an impressive rise in ASD with current prevalence estimates of 1/100 children (Fombonne, 2009; Kogan et al., 2009). In the majority of cases, the cause of ASD is unknown (Levy et al., 2009). Some autism susceptibility genes have been identified (Weiss et al., 2009), but gene interactions with environmental factors are increasingly suspected (Deth et al., 2008; Herbert, 2010). Recent reviews have focused mostly on genomic screens that suggest there are multiple gene interactions in autism; however no gene abnormality alone can explain the apparent increase in ASD prevalence (Durkin et al., 2010; Herbert, 2010; Miles, 2011). Increasing evidence suggests that there are different ASD endophenotypes, even within the ASD spectrum (Palmieri & Persico, 2010).