Scent of a disorder: olfactory functioning in schizophrenia.

The use of olfactory probes to assess frontal and temporal-limbic system functioning in patients with schizophrenia has garnered increasing interest among basic and clinical investigators. Deficits in odor identification, detection threshold sensitivity, discrimination, and memory have been reported and are thought to represent a centrally mediated deficit in the processing of this information. These impairments are seen in affected probands, first-degree family members, and those at risk for developing the illness, suggesting a genetic vulnerability or predisposition to chemosensory abnormalities. The observed deficits are not explained by gender, medication use, cognitive impairment, or smoking status, and support the hypothesis of primary dysfunction in the olfactory system. Along this same line, structural abnormalities in the peripheral and central olfactory brain regions, as well as disruptions of the basic physiology of this system, have been described. The study of olfactory processing in schizophrenia has already advanced the knowledge of the neural substrate for this disorder. Because the olfactory system continuously regenerates throughout life, it allows for a unique view of an ongoing neurodevelopmental process.