Growing genetic evidence including results of genome-wide
association studies and whole-genome sequencing is still perplexing scientists
in the fields of human complex traits and compels them to reconsider the
relationship between autism spectrum disorder (ASD) and schizophrenia. The
developmental trajectory of schizophrenia may be characterized by difficulties
in “theory of mind” tasks, poor insight or imagination, low empathy level, weak
executive function, failure in social judgments, delayed language
development, movement mannerisms, motoric rituals, strong preoccupation with
unusual objects, bizarre habits, and high intelligence. Most of these characteristics are associated with the standard criteria for ASD and all of them are
core domains or endophenotypes of ASD. The diagnosed ASD cases, which were
found in individuals with schizophrenia, have a significant tendency to be
highfunctioning and to have atypical age of ASD manifestation. Episodic
features including reality distortion, which can be seen in individual with
ASD, may be associated with hyperarousal conditions with cognitive hypersensitivity,
misattribution of negative experiences, and the perceptual thinking style.
Together with the emerging new genetic concepts concerning human behavioral
complex traits, the results and constructions of these recent studies may
further warrant that reconsideration of the relationship between ASD and psychotic
conditions is necessary. In addition, the possibility that psychotic conditions
are the secondary derivative states in individuals with ASD or in individuals
with subclinical ASD components should be constructively examined.