Olfactory hallucinations and olfactory identification ability in patients with schizophrenia and other psychiatric disorders.

Olfactory identification ability and the prevalence of olfactory hallucinations were examined in 183 hospitalized patients from three diagnostic groups. One hundred and thirty-one patients with schizophrenia, 21 patients with major depression, 31 women with eating disorders along with 77 normal control subjects were examined using the University of Pennsylvania Smell Identification Test (UPSIT) and were questioned regarding the presence of olfactory hallucinations. Olfactory identification deficits were observed only in patients with schizophrenia. In contrast, olfactory hallucinations were reported by members of all psychiatric diagnostic categories (34.6% of patients with schizophrenia; 19% of depressed patients and 29% of eating disorders patients). For patients with schizophrenia, women were more likely to report olfactory hallucinations and had higher UPSIT scores than men.