Olfaction and the 5-year incidence of cognitive impairment in an epidemiological study of older adults.
OBJECTIVE
To determine whether odor identification ability is associated with the 5-year incidence of cognitive impairment in a large population of older adults with normal cognition at baseline and whether olfactory impairment contributes to the prediction of cognitive decline.


METHODS
Population-based longitudinal study.


METHODS
Beaver Dam, Wisconsin.


METHODS
One thousand nine hundred twenty participants in the Epidemiology of Hearing Loss Study (mean age 66.9).


METHODS
Olfaction was measured using the San Diego Odor Identification Test (SDOIT). Incident cognitive impairment was defined as a Mini-Mental State Examination (MMSE) score of less than 24 or reported diagnosis of dementia or Alzheimer's disease (AD) at follow-up in participants with a MMSE score of 24 or greater and no diagnosis of dementia or AD at baseline.


RESULTS
There was a significant association between olfactory impairment at baseline and 5-year incidence of cognitive impairment (odds ratio (OR)=6.62, 95% confidence interval (CI)=4.36-10.05). The association remained significant after adjusting for possible confounders (OR=3.72, 95% CI=2.31-5.99). The positive predictive value of the SDOIT was 15.9%, the negative predictive value was 97.2%, the sensitivity was 55.1%, and the specificity was 84.4% for 5-year incidence of cognitive impairment.


CONCLUSIONS
Olfactory impairment at baseline was strongly associated with 5-year incidence of cognitive impairment as measured using the MMSE. Odor identification testing may be useful in high-risk settings, but not in the general population, to identify patients at risk for cognitive decline.
Schubert
Carla R
CR
Department of Ophthalmology and Visual Sciences, University of Wisconsin, Madison, Wisconsin, USA. Schubert@episense.wisc.edu
Carmichael
Lakeesha L
LL
Murphy
Claire
C
Klein
Barbara E K
BE
Klein
Ronald
R
Cruickshanks
Karen J
KJ
D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000453:epidemiology*; D003072:Cognition Disorders / Q000175:diagnosis / Q000453:epidemiology*; D015897:Comorbidity; D018450:Disease Progression; D005260:Female; D006801:Humans; D015994:Incidence; D008137:Longitudinal Studies; D008297:Male; D008403:Mass Screening; D008609:Mental Status Schedule; D008875:Middle Aged; D000857:Olfaction Disorders / Q000175:diagnosis / Q000453:epidemiology*; D012680:Sensitivity and Specificity; D012684:Sensory Thresholds; D012903:Smell; D013223:Statistics as Topic; D014922:Wisconsin