ABSTRACT

Autism spectrum disorders (ASD) are neurodevelopmental disorders characterized by repetitive movements and deficits in social communication. There are various etiological factors that contribute to the phenotype and wide range of symptoms and symptom severity is observed. Due to this diversity of symptoms and etiologies, today it is called "spectrum disorder". It is suggested that spectrum feature is not only observed in patients but also among the general population and has a continuity with etiological relevance. One argument for that ASD is that social adaptation and communication skills have a normal distribution among the population and that individuals at the negative end cannot adapt to the needs of population. Therefore, individuals at the end of this spectrum constitute the ASD group. Consistent with this view, studies examining autistic traits in healthy population have been increasing in recent years. Studies have focused first on unaffected family members of individuals with ASD and showed a significant deficiency in reciprocal social communication. At the same time, as ASD has high heritability, some of related genes are investigated in healthy population and found to be associated with some characteristics. In addition to differences in behavioral and genetic characteristics that have been reported in healthy subjects with autistic traits, neurophysiological differences are also found. By looking at these results, the structural and functional changes observed in healthy people with autistic traits are similar to ASD individiuals. As a result, considering physiological continuity between individuals with autistic traits and ASD, the argument of ASD being the negative end of normal distribution of social and communicative skills gains support.