When the Nose Doesn’t Know . . .

Seven years ago a publication in the American Journal of Psychiatry described how people with mild cognitive impairment had a deficit in the ability to smell. Around that time, pharmacies were selling scratch-and-sniff smell tests as diagnostic tools for detecting Alzheimer’s disease. They disappeared from the stores quite quickly, as I suspect the claims they were making hadn’t been validated.

A new report in the Archives of General Psychiatry has examined this approach to early diagnosis more thoroughly. Nearly 600 community-dwelling older people with normal mental functioning were given the 12-item Brief Smell identification Test. They were then ranked on the results of the smell test.

During the next 5 years 177 of the 589 participants developed mild cognitive impairment. Those people who scored in the lowest quarter of smell test results were 50% more likely to develop mild cognitive impairment than those ranked in the upper quarter of smell test results.

The test consisted of 12 familiar odors, with a choice of 4 answers for each. The average score at baseline was 9.3 (out of 12). Those scoring 8 or below were in the lower quarter, and those scoring 11 – 12 were in the upper quarter (or quartile).

The results seem conclusive. Maybe the scratch-and-sniff tests will re-appear in the pharmacies now?