Neuropsychological, neurological and symptom correlates of impaired olfactory identification in schizophrenia

Impaired olfactory identification has been reported in samples of schizophrenic patients. Little is known about the associations between these impairments and neuropsychological deficits, neurological deficits and olfaction-related symptoms. Forty-six subjects (37 men and 9 women) with schizophrenia were examined with the University of Pennsylvania Smell Identification Test (UPSIT), a selection of neuropsychological tests and standardised neurological and symptom evaluations. Eighty-five per cent of the subjects scored below the published norms' 10th percentile on the UPSIT. Stepwise multiple regression found that WAIS-R Information score and Wisconsin Card Sort Test Failure to Maintain Set score (WCST-FMS) were the only significant predictors of the UPSIT percentile scores, accounting for 41% of the variance. Neurological signs did not contribute to the prediction of impaired olfactory identification. Although 26% of subjects reported olfactory hallucinations, there was no association between this symptom and olfactory impairment. The results suggest that general knowledge or general intelligence may have some influence on olfactory identification in subjects with schizophrenia; however, olfactory identification deficit could not be explained by gross impairments of sustained attention, memory or conceptual ability.