Environmental Factors in the Onset of Autism Spectrum Disorder

Autism Spectrum Disorder (ASD) is a heterogeneous clinical condition, whose prevalence has grown considerably during the last decade. Genetic factors are thought to underpin the disorder, but common genetic variants and epigenetic mechanisms have been increasingly called into question for the majority of ASD cases. Growing prenatal exposure to new environmental toxicants has been shown to potentially affect brain development, leading to altered cognitive, social, attentive, behavioral and motor performance. Both epidemiological evidence and mechanistic studies assessing oxidative stress, neuroinflammation, epigenetic alterations and impaired signal transduction, all observed following neurotoxicant exposure, indeed lend biological plausibility to Gene x Environment interactions, whereby environmental toxicants interacting additively or synergistically with genetic liability, can push prenatal neurodevelopmental processes over the threshold for postnatal ASD expression. Research on environmental contributions to ASD and on specific Gene x Environment interaction models ultimately aims at defining targeted preventive strategies.