Odor identification and decline in different cognitive domains in old age.
The authors examined the association of odor identification with rate of decline in different cognitive systems. Participants are 481 older persons from the Rush Memory and Aging Project. At baseline, the Brief Smell Identification Test was administered. At annual intervals for up to 3 years, a battery of 19 cognitive tests was administered from which previously established composite measures of 5 cognitive domains were derived. In mixed-effects models adjusted for age, sex, and education, lower odor identification score was associated with lower function at baseline in each cognitive domain. Lower score was also associated with more rapid decline in perceptual speed (estimate=0.015, SE=0.006, p=0.013) and episodic memory (estimate=0.012, SE=0.006, p=0.030) but not with rate of decline in semantic memory, working memory, or visuospatial ability. Thus, on average, a person with a low odor identification score (6, 10th percentile) declined more than twice as rapidly in perceptual speed and episodic memory as a person with a high score (11, 90th percentile). Results were unchanged in subsequent analyses that controlled for cigarette smoking or clinically diagnosed stroke. The results indicate that impaired odor identification in old age is associated with impaired global cognition and more rapid decline in perceptual processing speed and episodic memory.
Wilson
Robert S
RS
Rush Alzheimer's Disease Center, Rush Institute for Healthy Aging, and Department of Neurological Sciences, Rush University Medical Center, Chicago, IL 60612, USA. rwilson@rush.edu
Arnold
Steven E
SE
Tang
Yuxiao
Y
Bennett
David A
DA
D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D003072:Cognition Disorders / Q000150:complications*; D005260:Female; D006801:Humans; D008297:Male; D000857:Olfaction Disorders / Q000209:etiology* / Q000503:physiopathology*