Autism and Asperger’s disorder (a better prognostic variety) that used to be classified under pervasive developmental disorders (PDD) in DSM-IV (1) are currently grouped under autistic spectrum disorders (ASD) in DSM-5 (2). These disorders were not recognized in the first and second editions of DSM in 1952 (3) and 1968 (4) and the closest term to them was “schizophrenic reaction of childhood type”! DSM-III in 1980 (5) introduced the PDD and classified them to childhood onset PDD, infantile autism, and atypical autism. In 1987, DSM-III-R (6) classified these disorders into PDD-NOS (not otherwise specified) and autistic disorder. In 1994, DSM-IV (7) classified these disorders into PDD-NOS, autistic disorder, Asperger disorder, childhood disintegrative disorder and Rett syndrome, that did not change in DSM-IV-TR in 2000. (8) The new DSM 5 published in may of 2014, with the explanation that all these disorders are along a spectrum and labeled them under the new term “Autistic Spectrum Disorders”.
Regardless of the terminology, ASD like schizophrenia are neurodevelopmental disorders and that is why in the past was classified under childhood psychoses or schizophrenic reaction of childhood. (9-13) These neurodevelopmental disorders, while share some common features in underlying pathogenesis and clinical manifestations, they have their own specific differences at both pathophysiologic and phenomenological levels. These disorders etiopathologically share an early insult to the developing brain, e.g. the prenatal maternal infections that trigger maternal and fetal immune reactions, damaging the fetal neurodevelopment. Although the insult such as infection could be non-specific, the severity, acuteness, latency of the invasion and the time window of neurodevelopment, determines which disorder to be manifested. (14) Moreover the pathophysiology of these neurodevelopmental disorders seems to be a multi-steps process. In the first step there is the microbial attack at a specific time of neurodevelopment that triggers the second step of maternal and fetal immune reaction response that would be damaging the fetal brain development. In the third step, the microbial invasion causes genetic mutations to pass on its impact to the next generation through genetic inheritance. In this paper, I will strive to present research evidence of the link between infective insults and the causation of ASD, e.g. autism, so hopefully to get us closer to the prevention of such disorders, by intervening in any of the above-mentioned steps, as the current treatments are nothing but symptomatic reliefs at the best!
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