Association Between Olfactory and Gustatory Dysfunction and Cognition in Older Adults

Abstract

Background: The association between olfactory dysfunction (OD) and cognitive decline is becoming apparent in the emerging literature. However, the literature demonstrating a similar effect between gustatory dysfunction (GD) and cognition is not well established.

Objective: To determine whether OD and GD are independently associated with cognitive impairment.

Methods: The 2013-2014 National Health and Nutrition Examination Survey was queried for 1376 older adults, corresponding to a weighted population sample of 50 816 529, to assess olfactory and gustatory status and cognition using univariate and multivariate regression analyses. OD and GD were determined using objective measurements with validated protocols. Participants were stratified as normal or abnormal cognition status using accepted cutoff values as indicated for the Consortium to Establish a Registry for Alzheimer's Disease (CERAD) neuropsychological test, Animal Fluency Test (AFT), and Digit Symbol Substitution Test (DSST).

Results: OD was associated with both mild cognitive impairment (odds ratio [OR] 1.809, P = .004) and dementia (OR 3.173, P < .001) with CERAD testing, abnormal AFT (OR 2.424, P < .001), and abnormal DSST (OR 4.028, P < .001). GD based on 1M NaCl whole mouth taste testing was associated with dementia on CERAD testing (OR 2.217, P = .004). When smell and taste parameters were included together in the regression model, both OD and GD remained significant independent predictors of dementia status based on CERAD testing (OR 3.133, P < .001, OR 1.904, P = .015).

Conclusions: OD and severe GD represent independent predictors of cognitive impairment in a nationally representative sample of older adults.

Keywords: Consortium to Establish a Registry for Alzheimer’s Disease; National Health and Nutrition Examination Survey; cognition; cognitive impairment; dementia; gustatory dysfunction; older adults; olfactory dysfunction; smell; taste.