Asymmetrical olfactory acuity and neuroleptic treatment in schizophrenia

Uni-rhinal olfactory acuity in schizophrenia was investigated in two experi ments. The first assessed the presence of a predicted atypical asymmetry of nostril laterality and the second assessed the effect of antipsychotic tre atment on the asymmetry. Although olfactory identification impairment has b een well documented in schizophrenia, olfactory acuity has been neglected. This may be an oversight as cerebral structures of the mesial temporal lobe important to olfactory perception have often been implicated in the pathop hysiology of schizophrenia and it is thus reasonable to postulate a primary impairment of olfactory acuity in schizophrenia. In addition, unmedicated patients with schizophrenia have exhibited asymmetrical laterality favourin g the right over the left hemisphere in studies of visual, haptic, and audi tory perception, and the few published prospective treatment studies have s uggested a reversal of this asymmetry with first generation neuroleptic tre atments. In experiment 1 a generalization of the perceptual asymmetry to ol factory acuity was examined by measurement of n-butanol olfactory threshold s with the Connecticut Chemosensory Perception Exam (CCPE) in an unmedicate d sample of 17 patients with schizophrenia and 17 age, gender, and handedne ss matched normal controls. The patient sample showed an asymmetrical impai rment of the left nostril that was not apparent in the normal control sampl e. In experiment 2, the CCPE was administered to a new sample of 10 patient s with schizophrenia before and after neuroleptic treatment. The asymmetry observed in experiment 1 was replicated, and the relative advantage of the right nostril shifted to a relative advantage of the left nostril over the course of 8 weeks of treatment. Results are discussed in relation to cerebr al aspects of schizophrenia and potential implications to cognitive change from treatment. (C) 2000 Elsevier Science B.V. All rights reserved.