Neuropsychological performance and family history in children at age 7 who develop adult schizophrenia or bipolar psychosis in the New England Family Studies

Abstract

Background: Persons developing schizophrenia (SCZ) manifest various pre-morbid neuropsychological deficits, studied most often by measures of IQ. Far less is known about pre-morbid neuropsychological functioning in individuals who later develop bipolar psychoses (BP). We evaluated the specificity and impact of family history (FH) of psychosis on pre-morbid neuropsychological functioning.

Method: We conducted a nested case-control study investigating the associations of neuropsychological data collected systematically at age 7 years for 99 adults with psychotic diagnoses (including 45 SCZ and 35 BP) and 101 controls, drawn from the New England cohort of the Collaborative Perinatal Project (CPP). A mixed-model approach evaluated full-scale IQ, four neuropsychological factors derived from principal components analysis (PCA), and the profile of 10 intelligence and achievement tests, controlling for maternal education, race and intra-familial correlation. We used a deviant responder approach (<10th percentile) to calculate rates of impairment.

Results: There was a significant linear trend, with the SCZ group performing worst. The profile of childhood deficits for persons with SCZ did not differ significantly from BP. Neuropsychological impairment was identified in 42.2% of SCZ, 22.9% of BP and 7% of controls. The presence of psychosis in first-degree relatives (FH+) significantly increased the severity of childhood impairment for SCZ but not for BP.

Conclusions: Pre-morbid neuropsychological deficits are found in a substantial proportion of children who later develop SCZ, especially in the SCZ FH+ subgroup, but less so in BP, suggesting especially impaired neurodevelopment underlying cognition in pre-SCZ children. Future work should assess genetic and environmental factors that explain this FH effect.

Figure 1

Full Scale IQ and Standardized Measures of Neuropsychological functioning at Age 7 in Adults who Developed Psychosis Including Persons with Schizophrenia Disorders (n=45), Bipolar Psychosis and Schizoaffective, Bipolar type combined (n=35), and Controls (n=101) *p < .05, **p<.01, ***p<.001 compared to controls (Least Square Means)

Figure 2

Profile analysis of mean performance and rates of abnormal performance on individual tests (<10%tile) of WRAT and WISC Performance at Age 7 for Adults who Subsequently Developed Psychosis, Including Schizophrenia and Schizoaffective Disorder, Depressed type (n=45), Bipolar Psychosis and Schizoaffective, Bipolar type combined (n=35), and Controls (n=101)

Figure 3

Full Scale IQ at 7 Years of Age for Adults That Subsequently Developed Psychosis With and Without a Family History of Psychosis in First-Degree Relatives, *p < .05, **p<.01, compared to controls. Controls (n=101), BP/SAB with no family history (N=13), BP/SAB with family history (N=16), Schizophrenia with no family history (N=28) and Schizophrenia with a positive family history of psychosis (N=8) (Least Square Means)