Etiological and Co-etiological Factors of Autism

1. Epigenetic factors 2. The prenatal environment: Obstructive sleep apnoea in pregnancy; Infectious processes; Environmental agents; Autoimmune and inflammatory diseases; Other maternity-related conditions. 3. Perinatal environment 4. Postnatal environment: Amygdala neurons; Autoimmune diseases 5. Intermezzo: the brain's immune system and its relationship with the gut 6. Postnatal environment: Gastrointestinal connections; Endogenous opiate precursor theory; Nutrition-related factors; Toxic exposure; Locus coeruleus-noradrenergic system; Oxidative stress. The role of genes is increasingly interpreted as a factor that interacts with others, generically called environmental factors, in determining the onset of the syndrome. For example, the possible involvement of particular conditions that may occur during foetal and neonatal development (pregnancy progression, infections contracted by the mother, factors linked to childbirth conditions) is being actively studied. An important area of research concerns the role of exposure to toxic agents during development. In this chapter, I will attempt to summarise 'the state of the art' on these important and seemingly increasingly relevant research fronts. In this context, it must necessarily be noted that, while it is true that the claim that cases of autism have increased disproportionately (as we shall see in more detail in the next chapter) is highly critical, it is also true that—if the relationship with broadly understood environmental factors were to be confirmed—at least part of this increase would be attributable to ecological changes over the last century, broadly understood. At present, many causes of autism have been proposed, but the understanding of the theory of autism causality is incomplete. As we have seen, an attempt has been made to incorporate known genetic and environmental causes into a causal framework. In its most recent definition, autism is a neurodevelopmental disorder characterised by impairments in communication skills and social interaction and limited/repetitive behaviours, interests or activities that are not appropriate to the individual's developmental stage, and the severity of symptoms and functional impairment vary from individual to individual. In recent years, the number of people diagnosed with the disorder has increased dramatically, at least taking into account official statistics. There are several potential reasons for this phenomenon, in particular changes in diagnostic criteria. In fact, it is evident that the broader the spectrum, the more open the criteria and the greater the number of cases that may fall within a descriptive case.