Age-related effects on the threshold, psychophysical function, and pleasantness of menthol.

Participants were 20 persons half of whom were 18 to 26 years of age (M = 21) and half of whom were over 65 years (M = 75). All were ambulatory, noninstitutionalized, and reported good to excellent health. The stimulus was menthol delivered in air to the nostrils. Threshold was measured using the up-down staircase method. Intensity and pleasantness were measured by magnitude estimation. The average threshold for the elderly participants was significantly higher than for young participants. The median slope of the intensity function was steeper by a factor of two for younger adults. The average pleasantness functions were steeper for the younger persons. Finally, although the younger adults found menthol less pleasant with repeated exposure, the elderly persons showed no effect of exposure. The results suggest that the average, healthy elderly person's odor/trigeminal world differs from that of the young adult. Further experiments are exploring the relative contributions of olfactory, trigeminal, and cognitive factors in producing this change.