Neurocognitive functioning in adult and adolescent offspring of parents with schizophrenia

Neurocognitive deficits have been proposed as endophenotypes for schizophrenia. Although neurocognitive functioning has been studied extensively in first-degree relatives of schizophrenia patients at single time points, little is known about the change or continuity in deficits across development.

The longitudinal sample was composed of 86 nonpsychotic participants who had a parent with schizophrenia (n = 28), a parent with a nonschizophrenia mental disorder (n = 31) or parents without mental illness (n = 27). Executive functioning (EF) was assessed during adolescence (M = 18 years) and adulthood (M = 32 years); attention and memory were assessed at adulthood.

The schizophrenia group, as adults, showed deficits in attention and memory relative to the no mental illness group. Only on one memory task did the schizophrenia group perform more poorly than the other mental illness group. Executive functioning improved with age for all three groups on Wisconsin Card Sorting Test perseverative errors; the rate of improvement was significantly slower for the schizophrenia and the other mental illness groups, compared to the no mental illness group. Stability in EF functioning over the 16-year period, measured by intraclass correlations, was low.

Adults at familial risk for schizophrenia showed deficits in neurocognitive functioning. The similarity of performance between those whose parents had schizophrenia and those whose parents had other mental illness, in all but the measures of memory, raises the question as to whether the neurocognitive functions examined are endophenotypes of vulnerability to schizophrenia specifically. Modest stability of EF and improved performance with age may reflect cortical maturation during early adulthood.