Perception of trigeminal chemosensory qualities in the elderly

One hundred healthy elderly subjects (65-88 years) were tested for their ability to: (i) assign verbal labels from a list of trigeminal type descriptors to six odorants known to have a strong trigeminal component; (ii) discriminate between intensity-matched pairs of these odorants in an odd-ball paradigm. Their performance was compared with that of 100 young controls (23--36 years). Young controls judged menthol and cineole as distinctly cool and fresh, acetic cid as pungent and sour and acetone as pungent, but showed no clear descriptive profile for ethanol and propanol. The descriptive profiles given by the elderly subjects correlated significantly with those given by the young controls for all six odorants and thus indicate a high degree of conformity in trigeminal perception of chemosensory qualities between the two age groups. In the odd-ball test the young controls correctly discriminated an average of 8.0 of 9 stimulus pairs presented, with most mistakes occurring in response to pairs with a similar trigeminal profile. With an average of 6.4 of 9 items correct, the discrimination performance of the elderly subjects was significantly poorer than that of the young controls but nevertheless significantly above chance at the group level with all 9 stimulus pairs. These results suggest that the nasal trigeminal system may experience some degree of age-related impairment but still contributes considerably to the perception and discrimination of chemosensory qualities in the elderly.