Carotid intima media thickness, atherosclerosis, and 5-year decline in odor identification: The beaver dam offspring study

Background. The purpose of this study was to determine if subclinical markers of atherosclerosis are associated with a decline in olfactory function. Methods. The San Diego Odor Identification Test was administered to 2,302 participants (age 21-84 years) at the baseline (2005-2008) and 5-year follow-up (2010-2013) examinations of the Beaver Dam Offspring Study. A decline in odor identification was defined as a decrease in San Diego Odor Identification Test score of 2 or more (range 0-8) from Beaver Dam Offspring Study 1 to Beaver Dam Offspring Study 2. Carotid intima media thickness and plaque, blood pressure, pulse wave velocity, and body mass index were measured and other risk factor data were obtained by interview. Results. Overall 3.2% of participants had a decline in San Diego Odor Identification Test score at 5 years. In age- and sex-adjusted models, mean intima media thickness (odds ratio = 1.17, 95% CI = 1.01, 1.34, per 0.1 mm) and number of sites (range 0-6) with carotid artery plaque (odds ratio = 1.35, 95% CI = 1.11, 1.65, per site) at baseline were associated with an increased risk for decline. Plaque score (odds ratio = 1.24, 95% CI = 1.01, 1.53) remained a significant independent predictor of olfactory decline in a model that included age, sex, hypertension, body mass index, alcohol, and smoking. Conclusions. Subclinical atherosclerosis was associated with an increased risk for olfactory decline indicating that atherosclerosis may be one of the risk factors for the decline in olfactory function seen with aging. Strategies to improve vascular health may also benefit olfactory health.