Olfactory identification deficits in schizophrenia: correlation with duration of illness

OBJECTIVE: The authors examined the relationship between deficits in olfactory identification and duration of illness in young and elderly patients with schizophrenia. METHOD: Olfactory identification performance of 38 patients with schizophrenia and 40 normal subjects was compared by using the University of Pennsylvania Smell Identification Test. RESULTS: The schizophrenic patients demonstrated olfactory deficits relative to the comparison group, and the elderly schizophrenic patients displayed a greater magnitude of olfactory deficit than the younger patients. Independent of normal aging effects and cognitive deficit, patients with schizophrenia showed a strong relationship between olfactory identification scores and duration of illness, which suggests that olfactory abilities decline progressively over the course of the disorder. CONCLUSIONS: In contrast to other neuropsychological measures that have been reported to be stable over the course of illness, olfactory identification abilities deteriorate steadily in patients with schizophrenia, even for those with relatively recent onset.