Impairment of olfactory identification ability in individuals at ultra-high risk for psychosis who later develop schizophrenia

Objective: Previous investigation has revealed stable olfactory identification deficits in neuroleptic-naive patients experiencing a first episode of psychosis, but it is unknown if these deficits predate illness onset. Method: The olfactory identification ability of 81 patients at ultra-high risk for psychosis was examined in relation to that of 31 healthy comparison subjects. Twenty-two of the ultra-high-risk patients (27.2%) later became psychotic, and 12 of these were diagnosed with a schizophrenia spectrum disorder. Results: There was a significant impairment in olfactory identification ability in the ultra-high-risk group that later developed a schizophrenia spectrum disorder but not in any other group. Conclusions: These findings suggest that impairment of olfactory identification is a premorbid marker of transition to schizophrenia, but it is not predictive of psychotic illness more generally.