Developmental instability and individual variation in brain development: Implications for the origin of neurodevelopmental disorders

Research on the origin of neurodevelopmental disorders has traditionally been pursued within a constrained, disorder-specific perspective. The developmental instability (DI) model described here offers a broader approach based on the evolutionary genetics of normal variation, reflecting our understanding that the processes generating genetic diversity are not unique to any specific disorder. The DI model helps account for shared features, including atypical functional and anatomic asymmetries, reduced general intellectual functioning, and complex patterns of heritability, across different types of neural variation. The model suggests research strategies that may help illuminate the specific and unique causal factors characterizing different types of neural variation.