On childhood intellectual decline of adult schizophrenics: a reassessment of an earlier study.

An earlier study (Lane & Albee, 1963) reported that school-age children who later become schizophrenic adults show a significant decline in intelligence-test performance between early and late childhood. Because a control group of 872 children from the same school system showed a slight gain in IQ score on the same two tests taken at the same ages, it was concluded that the decline in IQ represents a genuine decrease in intellectual function which distinguishes preschizophrenics from other children. The conclusions of this study have been cited by others (Mednick, 1965; Segal, 1966; Yates, 1966). Recently, however, in a reexamination of the composition of the control group and of the problems involved in comparing results from two different intelligence tests, the authors became dissatisfied with these conclusions. Is the reported decline in intelligence during childhood related to socioeconomic factors that were not controlled or is it characteristic of schizophrenia? Does this loss in IQ points represent differences between two tests or a genuine decline in intellectual level? The majority of the future schizophrenics came from the lowest socioeconomic levels and generally scored below average even on the first test, while the children in the con-