Genetic, neurobiological, and environmental convergences and divergencies between autism and the spectrum of schizophrenia

Abstract

Introduction: The autistic spectrum and the schizophrenia spectrum and other psychotic disorders concur more frequently than would be expected by chance alone. This article analyzes the evidence related to convergent and divergent risk factors at a genetic, neuroanatomical and environmental level that could explain this greater co-occurrence between both conditions.

Development: The high number of deletions and shared CNV duplications, including the genes NRXN1, CNTNAP2, 22q11.2, 1q21.1 and 15q13.3, mutations Shank3 and 7q11.23, among others, definitively calls into question the assumption that the spectrum of the schizophrenia and autism are 2 etiologically totally differentiated conditions. The epigenetic effects contribute to brain cytoarchitecture anomalies in both spectra related to the volume of gray matter, reduced values of fractional anisotropy, hypoactivation patterns of certain cerebral structures, alterations in brain connectivity and neurochemicals among others. Autism and the spectrum of schizophrenia and other psychotic disorders also share environmental risk factors, many of them related above all with obstetric complications and paternal age.

Conclusion: There is a genotypic overlap between the spectrum of autism and the spectrum of schizophrenia and other psychotic disorders that supports the hypothesis that both conditions may emerge from common shared pathogenic mechanisms. These mechanisms, together with environmental risk factors, would explain some of the neurobiological similarities. It is important to clarify that phenotypically remain 2 clearly differentiated conditions and that the possible appearance of psychotic symptoms in a subgroup of people with autism does not necessarily imply the development of schizophrenia.