Schizophrenia: neuroinflammation, neurodegeneration or neurodevelopment? A genetic overview
Schizophrenia is a devastating mental illness and its etiology is still largely unknown. Several gene mapping studies suggest that schizophrenia is a complex disorder, with a cumulative impact of variable genetic effects coupled with environmental factors. There is evidence that schizophrenia could be a neurodegenerative, neuroinflammatory or neurodevelopmental disorder. Neuropsychological data indicate neurocognitive functions are relatively stable over time after illness onset, whereas morphological data indicate a degenerative process; potential roles of neuroinflammation in the etiology of psychiatric diseases including schizophrenia have also been suggested. Recent research indicates genetic overlap between schizophrenia and syndromes in which psychopathology manifests in childhood and that are often grouped together as ‘neurodevelopmental disorders’. These findings challenge the etiological basis of current diagnostic categories and, together with evidence for frequent comorbidity, suggest that we should view the functional psychoses as members of a group that result in part from a combination of genetic and environmental effects on brain development and that are associated with specific and general impairments of cognitive function. The objective was to perform a systematic literature review of articles on genetics of schizophrenia relating to neurodegeneration, neuroinflammation and neurodevelopment. After proper filter, we included 40 studies and reviewed each finding and its relevance to the hypotheses. We can conclude that the evidence points to schizophrenia as a neurodevelopmental disease with the direct presence of factors related to neuroinflammation and neurodegeneration.