Cerebral lateralization is delayed in children who later develop schizophrenia.

The origins of schizophrenia are obscure. One suggestion is that it represents a component of the genetic variation associated with the establishment of dominance in one or other cerebral hemisphere, a mechanism that has been crucial in the evolution of language. Indices of cerebral hemispheric dominance (hand, foot and eye preference, speed of checking squares) recorded on the 16,980 children in the UK National Child Development Study cohort were examined in relation to psychiatric admission by the age of 28 years. Diagnoses were established by the application of Present State Examination criteria to case notes. Pre-schizophrenic children (n = 34-36) were more likely (p < 0.0003) to be rated by their mothers as ambidextrous at the age of 7 years, and at 11 years were less (p < 0.01) strongly right-handed than their peers in the cohort population on a test of relative hand skill: children who later developed affective psychosis (n = 25) or neurosis (n = 60) did not differ significantly from controls. Delay in establishing dominance in one hemisphere could be the critical factor that predisposes to schizophrenia.