Olfactory dysfunction in schizophrenia: A qualitative and quantitative review

Olfactory dysfunction in patients with schizophrenia has been a topic of in creasing interest, with deficits in odor identification, detection threshol d sensitivity, discrimination, and memory being reported. Despite increasin g knowledge, controversy has existed about possible differential deficits a mong olfactory tests as well as the influences of gender, smoking and medic ation status on olfactory measures. To help elucidate some of this controve rsy, we conducted a qualitative and quantitative (meta-analytic) review of the English language literature on olfaction in schizophrenia. Moderator va riables such as gender, medication status, and smoking history were also ex amined. Results indicated that substantial olfactory deficits, across all d omains, are observed in patients with schizophrenia. No differential defici ts were observed across domains of odor identification, detection threshold sensitivity, discrimination, and memory. The influences of gender, medicat ion status, and smoking on effect sizes were not significant across studies . This supports the hypothesis of primary dysfunction in the olfactory syst em that is regulated by brain regions where structural and functional abnor malities have also been reported in neuroimaging studies. (C) 1999 American College of Neuropsychopharmacology. Published by Elsevier Science lure.