Developmental instability in social anhedonia: an examination of minor physical anomalies and clinical characteristics.

Developmental instability (DI) refers to the inability of the developing brain to buffer the effects of genetic and environmental insults. This concept has been invoked to better understand how fetal brain development goes awry in schizophrenia and related spectrum disorders. This study examined one marker of DI, minor physical anomalies (MPAs), and its association with a putative indicator of schizotypy, the trait of social anhedonia. MPAs and clinical symptoms were assessed within a community sample of psychometrically identified individuals high in social anhedonia and a matched group of healthy controls. Results indicated that, compared to the controls, MPAs were elevated in the social anhedonia group. Additionally, within the social anhedonia group, MPAs were significantly correlated with clinical ratings of schizoid personality disorder characteristics and also showed strong associations with schizotypal personality disorder ratings. These findings indicate a relationship between developmental anomalies and negative schizotypy and suggest that, when combined with psychometrically identified risk, the presence of MPAs may further elevate the probability of clinical manifestations of schizophrenia-spectrum characteristics.