Premorbid performance IQ deficit in schizophrenia
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Updated: Oct 10, 2026

Development of a Virtual Reality Assessment of Everyday Living Skills
Published on: April 23, 2014
G P Amminger1, M Schlögelhofer, T Lehner
1University Hospital for Child and Adolescent Neuropsychiatry, Vienna, Austria.
Objective:
Performance IQ (PIQ) is often lower than verbal IQ (VIQ) in schizophrenic patients. Whether PIQ < VIQ precedes psychotic symptoms in schizophrenia remains uncertain.
Method:
We investigated premorbid IQ scores in 63 subjects assessed at a child and adolescent psychiatric unit (mean age 13.1 years, SD 3.2), who at follow-up in adulthood (mean age 30.9 years, SD 3.9) received a lifetime RDC diagnosis of schizophrenia-related psychosis, affective disorder, or no psychiatric disorder.
Results:
Premorbid PIQ < VIQ significantly differentiated the groups with schizophrenia-related psychosis and no psychiatric disorder. Subjects with schizophrenia-related psychosis had a significantly lower mean value for premorbid PIQ, but not VIQ, compared to subjects who developed affective disorder or subjects without psychiatric disorder.
Conclusion:
Our results emphasize premorbid intellectual deficits in schizophrenia. Those deficits might largely be in consequence of an impairment on the PIQ scale.
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