Abstract
ObjectiveThis study aimed to evaluate the value of odors in the olfactory identification (OI) test and other known risk factors for predicting incident dementia in the prospective Shanghai Aging Study.MethodsAt baseline, OI was assessed using the Sniffin’ Sticks Screening Test 12, which contains 12 different odors. Cognition assessment and consensus diagnosis were conducted at both baseline and follow-up to identify incident dementia. Four different multivariable logistic regression (MLR) models were used for predicting incident dementia. In the no-odor model, only demographics, lifestyle, and medical history variables were included. In the single-odor model, we further added one single odor to the first model. In the full model, all 12 odors were included. In the stepwise model, the variables were selected using a bidirectional stepwise selection method. The predictive abilities of these models were evaluated by the area under the receiver operating characteristic curve (AUC). The permutation importance method was used to evaluate the relative importance of different odors and other known risk factors.ResultsSeventy-five (8%) incident dementia cases were diagnosed during 4.9 years of follow-up among 947 participants. The full and the stepwise MLR model (AUC = 0.916 and 0.914, respectively) have better predictive abilities compared with those of the no- or single-odor models. The five most important variables are Mini-Mental State Examination (MMSE) score, age, peppermint detection, coronary artery disease, and height in the full model, and MMSE, age, peppermint detection, stroke, and education in the stepwise model. The combination of only the top five variables in the stepwise model (AUC = 0.901 and sensitivity = 0.880) has as a good a predictive ability as other models.ConclusionThe ability to smell peppermint might be one of the useful indicators for predicting dementia. Combining peppermint detection with MMSE, age, education, and history of stroke may have sensitive and robust predictive value for dementia in older adults.
Highlights
Olfactory dysfunction is a common feature of neurodegenerative diseases, especially in dementia (e.g., Alzheimer’s disease, dementia with Lewy bodies, and Parkinson’s disease dementia), and is considered to be a premotor sign of neurodegeneration (Attems et al, 2014)
Previous hospital- and populationbased studies have demonstrated the association of olfactory dysfunction with dementia, cognitive decline, or mild cognitive impairment (MCI)
At the baseline of our Shanghai Aging Study, we found a lower score on the olfactory identification (OI) test and a reduced ability to identify odors of peppermint, orange, pineapple, cinnamon, coffee, fish, banana, rose, leather, and licorice in participants with MCI compared to those with normal cognition (Liang et al, 2016)
Summary
Olfactory dysfunction is a common feature of neurodegenerative diseases, especially in dementia (e.g., Alzheimer’s disease, dementia with Lewy bodies, and Parkinson’s disease dementia), and is considered to be a premotor sign of neurodegeneration (Attems et al, 2014). At the baseline of our Shanghai Aging Study, we found a lower score on the olfactory identification (OI) test and a reduced ability to identify odors of peppermint, orange, pineapple, cinnamon, coffee, fish, banana, rose, leather, and licorice in participants with MCI compared to those with normal cognition (Liang et al, 2016). We further verified these findings in the 5-year prospective phase and explored the association of inability to smell peppermint with a higher dementia onset risk (HR = 2.67, 95% CI: 1.44, 4.96) by using a multivariable logistic regression (MLR) model (Liang et al, 2020). The previous study did not evaluate the performance (or predictive value) of peppermint in predicting incident dementia
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
