Increased olfactory sensitivity in first episode psychosis and the effect of neuroleptic treatment on olfactory sensitivity in schizophrenia

Olfactory sensitivity to two odorants, isoamyl acetate and androstenone, was assessed in 19 male schizophrenic patients and 10 control subjects. Tests were performed during a drug-free period and 2-3 weeks after initiation of neuroleptic drug therapy. Olfactory sensitivity in schizophrenic patients was significantly impaired during the drug-free period and neuroleptic treatment further reduced olfactory sensitivity in these patients. The same olfactory tests were administered to 22 first-episode-psychosis patients, 12 first- episode-schizophrenia and 10 brief-psychotic-disorder patients, as well as to 20 age-matched control subjects. The first-episode-psychosis patients had significantly higher sensitivity to isoamyl acetate and to androstenone, but the incidence of anosmia to androstenone was not higher in the first episode patient group as compared to the control group. We conclude that olfactory dysfunction in schizophrenic patients, and possibly other forms of psychosis, is mainly due to long-term effects of commonly used neuroleptic drugs.