Eating difficulty, dental status, and functional vulnerability in relation to cognitive outcomes across four ageing...

To determine whether newly reported eating difficulty or dental-status problems precede abrupt cognitive decline or identify broader functional vulnerability.

Cognition, dementia indicators, and oral/eating measures were harmonised across the China Health and Retirement Longitudinal Study, English Longitudinal Study of Ageing, Health and Retirement Study, and Survey of Health, Ageing and Retirement in Europe. First observed transitions in eating difficulty, tooth loss or poor dental health, and any oral/eating difficulty were matched within cohort and wave. Cognitive slopes, fixed-window dementia indicators, cognition-only outcomes, a non-eating activities of daily living comparator, functional context, persistence, and reverse direction were examined.

Analyses included 219,047 participants and 722,637 person-waves. Matched 6-year dementia-indicator risk differences (RDs) per 1000 were 91.5 (95% confidence interval [CI], 42.4 to 140.6) for eating difficulty, 39.5 (95% CI, -9.6 to 88.6) for any oral/eating difficulty, and 13.5 (95% CI, -25.3 to 52.4) for tooth loss or poor dental health. Adjusted differences were 88.4, 7.0, and approximately 0 per 1000, respectively. Conventional random-effects context and course analyses showed 105.1 per 1000 (95% CI, 50.4 to 159.7) for eating difficulty with another functional limitation and 202.1 per 1000 (95% CI, 67.6 to 336.6) for eating difficulty reported at consecutive observed waves. Event-time models showed no abrupt acceleration, and low cognition predicted later eating-difficulty onset.

Eating difficulty marked broader functional vulnerability rather than an oral-specific cognitive trigger. Dental and primary-care encounters may provide an opportunity for broader assessment, but the findings do not support an isolated dental screening rule.

The largest RDs were observed when newly reported eating difficulty accompanied other functional limitations or was reported again at the next observed wave; structural dental status showed little adjusted association. In dental and primary-care encounters, the item may support broader functional and cognitive assessment, but it should not be used as an oral-specific dementia screening test.