Among older persons without manifest cognitive impairment, difficulty in identifying odors such as lemon, banana, soap and cinnamon predicts subsequent development of Mild Cognitive Impairment MCI which is often a precursor to Alzheimer’s disease.
The study published in July edition of the Archives of General Psychiatry.
Researchers followed 589 community-dwelling older persons without cognitive impairment at study baseline, at which time odor identification was assessed using the 12-item Brief Smell Identification Test.
The odors volunteers were asked to identify were banana, onion, soap, cinnamon, lemon, black pepper, smoke, paint thinner, pineapple, gasoline, rose and chocolate.
During annual observation of up to 5 years, 177 subjects developed Mild Cognitive Impairment MCI. In a proportional hazards model adjusted for age, sex, and education, odor identification score predicted development of MCI, with risk increased by 50% in persons with below-average compared with above-average odor identification scores.
Lead author Robert Wilson of Chicago’s Rush University Medical Center said a diminishing sense of smell isn’t cause for panic. “Not all low scorers went on to have cognitive problems,” Wilson said.
The study was funded by the National Institute on Aging and the Illinois Department of Public Health.