Association between tooth loss and cognitive decline: A 13-year longitudinal study of Chinese older adults

OBJECTIVES To examine the association between the number of teeth remaining and cognitive decline among Chinese older adults over a 13-year period. DESIGN A large national longitudinal survey of Chinese older adults. SETTING The Chinese Longitudinal Healthy Longevity Survey (CLHLS) (1998-2011). PARTICIPANTS A total of 8,153 eligible participants aged 60+ interviewed in up to six waves. MEASUREMENTS Cognitive function and teeth number were measured at each interview. Cognitive function was measured by the Mini-Mental Status Examination (MMSE). Number of natural teeth was self-reported. Individuals with severe cognitive impairment were excluded. Covariates included demographic characteristics, adult socioeconomic status characteristics, childhood socioeconomic status, health conditions, and health behaviors. Linear mixed models were applied in the analysis. RESULTS The mean teeth number at baseline was 17.5(SD = 0.1), and the mean of baseline cognitive function was 27.3(SD = 0.0). Cognitive function declined over time (β = -0.19, P < .001) after controlling covariates. But, regardless of time, more teeth were associated with better cognitive function (β = 0.01, P < .001). The interaction of teeth number and time was significant (β = 0.01, P < .001), suggesting that the participants who had more teeth showed a slower pace of cognitive decline over time than those with fewer teeth after controlling for other covariates. CONCLUSION This study showed that tooth loss was associated with cognitive decline among Chinese older adults. Further studies are needed to examine the linkages between cognitive decline and oral health status using clinical examination data.