Influences of ethanol ingestion on olfactory function in humans.
RATIONALE
Although ethanol is known to influence, in humans, psychophysical measures of visual, auditory, and vestibular function, the influence of this drug on the ability to smell is not clear.


OBJECTIVES
To evaluate, in eight men and eight women, the influences of ethanol ingestion on four well-validated measures of olfactory function: an ethanol odor detection threshold test, a phenyl ethyl alcohol odor detection threshold test, a 40-item smell identification test, and an odor discrimination/short-term odor memory test.


METHODS
In this double-blind experiment, grape juice alone was administered prior to the olfactory tests on one test occasion, and a grape juice-vodka mixture, designed to produce blood levels of ethanol near the legal level of intoxication, on another. The order of the two drug conditions was counterbalanced, as was the order of the presentation of the olfactory tests.


RESULTS
Ethanol ingestion markedly influenced the detection threshold for ethanol (all 16 subjects exhibited higher thresholds under the ethanol than under the non-ethanol condition) and had a significant, albeit small, influence on odor discrimination performance, as measured by the total number of correct responses independent of delay interval. Women performed significantly better than men on the latter measure. No influences of ethanol on odor identification, the phenyl ethyl alcohol detection threshold, or the delay interval (memory) component of the odor discrimination/memory test were observed.


CONCLUSIONS
Alcohol ingestion markedly and selectively alters olfactory sensitivity to ethanol, perhaps via habituation processes, and may subtly influence some measures of odor discrimination.