A simple
odor identification test might help doctors more accurately predict
which individuals with mild cognitive impairment will go on to develop
Alzheimer's disease, according to research funded by the National
Institute on Aging and the National Institute of Mental Health, two
components of the National Institutes of Health in Bethesda, Maryland.
In the
study, D. P. Devanand, M.D., and colleagues at Columbia Presbyterian
Medical Center in New York asked 90 men and women who had minor memory
problems and other mild cognitive impairments to participate in a
15 to 20 minute "scratch and sniff" test. The participants,
whose mean age was 67, were exposed to 40 distinct smells such as
menthol, peanuts and soap. Each odor was embedded in a microcapsule
on a separate page. After scratching open the capsule and smelling
its contents, each participant was asked to identify the odor from
four alternatives listed for each capsule. The study is reported in
the September issue of the American Journal of Psychiatry.
None
of the 30 individuals who scored well on the test developed Alzheimer's
disease during the follow-up period, which averaged 20 months. But
the researchers found 19 of 47 people with mild cognitive impairment
who had difficulty identifying these smells or odors went on to develop
Alzheimer's disease during the follow-up period. Of those 19, 16 reported
that they had a good sense of smell at the time of the test, yet scored
poorly on it. This finding suggests that the inability to recognize
smells, when combined with a lack of awareness that olfactory senses
are impaired, might be used as a predictor of impending Alzheimer's
disease. Thirteen of the 90 participants in this study had not completed
follow-up at the time of publication.
