• Within a sample of 60 children of schizophrenic parents, IQ and the correlates of IQ were examined. The Wechsler intelligence Scale for Children was administered at age 7. The offspring of parents with schizophrenia were found to have a slightly lower IQ than their matched controls. This deficit could be attributed entirely to the male offspring.
Using a second comparison group numbering several thousand, we computed correlations for various perinatal and socioeconomic factors with seven-year IQ. These correlations were also computed for the children of schizophrenics, and the difference in correlations was examined. iQs for the offspring of "continuous schizophrenics" (chronic, borderline, and chronic schizo-affective schizophrenics) were found to have lower correlations with socioeconomic indices and higher correlations, in a negative direction, with certain perinatal events. The findings were found to a lesser, nonsignificant degree among the small sample of offspring of acute schizophrenics. If these perinatal events are more negatively correlated with IQ because the children of continuous schizophrenics are specifically susceptible to them, it is possible that these factors are also influential in the later development of schizophrenia.
Rieder RO, Broman SH, Rosenthal D. The Offspring of SchizophrenicsII. Perinatal Factors and IQ. Arch Gen Psychiatry. 1977;34(7):789-799. doi:10.1001/archpsyc.1977.01770190051004