Physiologic impairment of olfactory stimulus processing in schizophrenia.
BACKGROUND
Behavioral studies of olfaction have demonstrated impairments in the ability to detect and identify odors in patients with schizophrenia. These deficits appear to be independent of either symptom severity or other cognitive impairment. Only limited efforts have been made to investigate the neurophysiologic substrate of these olfactory abnormalities. This article reports the first examination of olfactory electrophysiologic responses in patients with schizophrenia.


METHODS
Olfactory event-related potential responses to three different concentrations of hydrogen sulfide were recorded in a sample of 21 patients and 20 healthy control subjects. Odors were presented via an olfactometer to ensure there was no associated trigeminal nerve stimulation.


RESULTS
Patients exhibited abnormalities in the amplitudes of the N1 and P2 components of the olfactory evoked potential, and delayed latency of the P2. The N1 abnormality, which denotes primary olfactory cortex activity, was related to impaired odor detection threshold sensitivity; the P2 abnormality was related to impaired odor identification.


CONCLUSIONS
These data indicate the presence of a primary physiologic impairment in the olfactory cortex underlying behavioral olfactory deficits seen in patients with schizophrenia. This is consistent with postmortem and in vitro studies suggesting abnormalities in olfactory receptor neurons. Understanding the nature of these physiologic olfactory impairments could offer clues to the basic neuropathology of this disorder.
Turetsky
Bruce I
BI
Schizophrenia Research Center, Department of Psychiatry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
Moberg
Paul J
PJ
Owzar
Kiana
K
Johnson
Sarah C
SC
Doty
Richard L
RL
Gur
Raquel E
RE
D000293:Adolescent; D000328:Adult; D000393:Air Pollutants / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004594:Electrophysiology / Q000379:methods; D005071:Evoked Potentials / Q000187:drug effects / Q000502:physiology*; D005260:Female; D006801:Humans; D006862:Hydrogen Sulfide / Q000494:pharmacology; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009812:Odorants; D009833:Olfactory Pathways / Q000187:drug effects / Q000503:physiopathology; D011601:Psychophysics / Q000379:methods; D011930:Reaction Time; D012559:Schizophrenia / Q000188:drug therapy / Q000503:physiopathology*; D012903:Smell / Q000187:drug effects / Q000502:physiology*; D013268:Stimulation, Chemical
D000393:Air Pollutants; D006862:Hydrogen Sulfide