Olfactory identification deficiency and WCST performance in men with schizophrenia.

Several studies using the University of Pennsylvania Smell Identification Test (UPSIT), which requires forced choice olfactory identifications, have reported olfactory identification deficits in patients with schizophrenia. This report examines the possible links between olfactory identification (usually attributed to the orbitofrontal cortex) and executive functions (usually attributed to dorsolateral prefrontal cortex) in 24 male patients with schizophrenia and 21 male comparison subjects. Olfactory performance was investigated under two conditions: spontaneous identification and forced choice identification. Executive function was assessed with the Wisconsin Card Sorting Test (WCST). Compared with controls, patients with schizophrenia exhibited a higher average number of cigarettes smoked per day, lower spontaneous identification scores on olfactory performance, and a higher percentage of perseverative errors on the WCST; there was a significant relationship between the two performance measures. Simpson-Angus scores, neuroleptic drug treatment levels, and scores on the Positive and Negative Syndrome Scale were not correlated with either olfactory measure. The lack of correlation between the forced choice olfactory identification score and the WCST score is consistent with findings in previous studies that used the UPSIT. By contrast, use of a spontaneous identification condition to assess olfactory performance did produce a significant association with WCST performance.