Olfaction and cognition in schizophrenia: sex matters.

Cognitive and olfactory deficits occur in schizophrenia, but little is known whether sex modifies these deficits. We examined the relationship between olfaction and cognition in 55 schizophrenia patients and 32 healthy controls. Patients and controls demonstrated significant differences performing cognitive tasks. In patients, sex modified all relationships of odor identification to cognition. Female patients showed significantly stronger trends than male patients correlating better smell identification with higher scores on intelligence, memory, and attention, whereas their correlations of odor identification with executive functioning contradicted those of male patients. Odor acuity significantly correlated with several cognitive measures, especially in male patients, in whom better acuity was generally associated with better cognition. Female patients again differed significantly from males; odor acuity correlations with cognitive measures were weaker, or contradicted, those of male patients. These findings indicate significant sex differences in olfactory processing in schizophrenia. Combining the sexes in research analyses may obscure important differences.