Olfactory physiological impairment in first-degree relatives of schizophrenia patients

Turetsky, Bruce I.; Kohler, Christian G.; Gur, Raquel E.; Moberg, Paul J.

doi:10.1016/j.schres.2008.03.013

« Previous Next »Schizophrenia Research
Volume 102, Issue 1 , Pages 220-229, July 2008

Olfactory physiological impairment in first-degree relatives of schizophrenia patients

Bruce I. Turetsky
- Neuropsychiatry Division, Department of Psychiatry, University of Pennsylvania School of Medicine, 3400 Spruce Street, Philadelphia, Pennsylvania, 19104, USA
- Smell and Taste Center, Department of Otorhinolaryngology, Head and Neck Surgery, University of Pennsylvania School of Medicine, 3400 Spruce Street, Philadelphia, Pennsylvania, 19104, USA
- Corresponding author. Neuropsychiatry Division, Department of Psychiatry, 10th Floor, Gates Building, University of Pennsylvania, 3400 Spruce Street, Philadelphia, PA 19104, USA. Tel.: +1 215 615 3607; fax: +1 215 662 7903.
Christian G. Kohler
- Neuropsychiatry Division, Department of Psychiatry, University of Pennsylvania School of Medicine, 3400 Spruce Street, Philadelphia, Pennsylvania, 19104, USA
Raquel E. Gur
- Neuropsychiatry Division, Department of Psychiatry, University of Pennsylvania School of Medicine, 3400 Spruce Street, Philadelphia, Pennsylvania, 19104, USA
Paul J. Moberg
- Neuropsychiatry Division, Department of Psychiatry, University of Pennsylvania School of Medicine, 3400 Spruce Street, Philadelphia, Pennsylvania, 19104, USA
- Smell and Taste Center, Department of Otorhinolaryngology, Head and Neck Surgery, University of Pennsylvania School of Medicine, 3400 Spruce Street, Philadelphia, Pennsylvania, 19104, USA

Received 24 January 2008; received in revised form 10 March 2008; accepted 17 March 2008. published online 06 May 2008.

Abstract

Background

Efforts to characterize genetic vulnerability to schizophrenia are increasingly focused on the identification of endophenotypes — neurobiological abnormalities that are evident in individuals at risk. Behavioral studies have demonstrated olfactory impairments in odor detection and identification in unaffected 1st-degree relatives of schizophrenia patients, suggesting that abnormalities in this simple sensory system may serve as candidate endophenotypes. It is unclear, however, whether these behavioral abnormalities reflect basic olfactory sensory processing deficits or nonspecific disruptions of attention and cognition.

Method

Unirhinal chemosensory olfactory evoked potentials were acquired from 14 unaffected 1st-degree relatives of schizophrenia patients and 20 healthy individuals with equivalent age and gender distributions, using 3 different concentrations of hydrogen sulfide. Subjects were also assessed behaviorally for ability to detect and identify odors.

Results

Family members exhibited left nostril olfactory detection impairments and bilateral olfactory identification abnormalities. They had reduced evoked potential response amplitudes for the initial N1 component in the left nostril. The subsequent P2 evoked potential response was reduced bilaterally. The pattern and magnitude of family member deficits were comparable to those previously observed for schizophrenia patients.

Conclusion

1st-degree relatives of schizophrenia patients exhibit specific neurophysiological impairments in early olfactory sensory processing. The presence of these neurophysiological abnormalities in both schizophrenia patients and their unaffected 1st-degree relatives suggests that these represent genetically mediated vulnerability markers or endophenotypes of the illness.

Keywords: Schizophrenia, Olfaction, Endophenotype, Evoked potentials, Genetic vulnerability