Dysfunctions in olfactory processing in schizophrenia

Purpose of review Given that the olfactory. system projects to brain regions frequently implicated in the pathophysiology of schizophrenia, the past few years have witnessed growing interest in olfactory processing in this disorder. Studies of olfactory functioning reported since June 2001 are reviewed. Recent findings New research has focused primarily on consistently reported impairments in odor identification in schizophrenia. It reflects clinically relevant issues that have been described in the assessment of olfactory dysfunction in schizophrenia, including the following: the potential of a vulnerability marker; a tool for assisting localization of cerebral pathology; and the possibility of classifying patients into meaningful discrete subtypes. Summary Despite the progress that has been made, significant challenges lie ahead. A new intriguing avenue for further investigation may be the assessment of various types of olfactory processing in schizophrenia, such as odor judgements, that are believed to represent steps in the process of odor identification. Further research utilizing comprehensive behavioural as well as neuroimaging measures in the assessment of olfactory processing is needed, and may provide useful theoretical and diagnostic information in schizophrenia.