Background: Finding risk indicators for schizophrenia among groups of individuals at high genetic risk for the disorder, has been the driving force of the high risk paradigm. The current study describes the preliminary results of a neuropsychological assessment battery conducted on the first 50% of subjects from the Edinburgh High Risk Study.
Methods: One hundred and four high risk subjects and 33 normal controls, age and sex matched, were given a neuropsychological assessment battery. The areas of function assessed and reported here include intellectual function, executive function, perceptual motor speed, mental control/ encoding, verbal ability and language, learning and memory measures, and handedness.
Results: The high risk subjects performed significantly more poorly than the control subjects in the following domains of neuropsychological function: intellectual function, executive function, mental control/encoding and learning, and memory. Controlling for IQ, high risk subjects made significantly more errors on the Hayling Sentence Completion Test (HSCT), took longer to complete section A of the HSCT, had lower scores on the delayed recall condition of the visual reproductions subtest of the Wechsler Memory Scale-Revised, and had significantly poorer Rivermead Behavioural Memory Test (RBMT) standardized scores. The presence of significant group by IQ interactions for the RBMT and time to complete section A of the HSCT suggested that differences among the groups were more marked in the lower IQ range. Performance on the HSCT was found to be related to the degree of family history of schizophrenia.
Conclusions: High risk subjects performed more poorly than controls on all tests of intellectual function and on aspects of executive function and memory.