Trajectories of socioeconomic status, non-communicable diseases, and chronic pain in relation to dementia risk among middle-aged and older adults: A multi-cohort longitudinal study

OBJECTIVE: Evidence on the long-term joint effects of socioeconomic and health-related burdens on dementia risk remains limited. This study examined whether longitudinal trajectories of socioeconomic status (SES), non-communicable diseases (NCDS), and chronic pain (CP), individually and jointly, were associated with dementia risk among middle-aged and older adults. METHODS: We analyzed data from six longitudinal aging cohorts. Cox proportional hazards models were used to estimate associations between SES, NCDS, CP, and dementia risk, with results pooled across cohorts. Trajectory and joint trajectory analyses were conducted to characterize long-term patterns of these factors, and lagged analyses assessed robustness. RESULTS: Pooled estimates showed that higher SES was associated with a lower risk of dementia (HR 0.84, 95% CI 0.76-0.92), whereas NCDS (HR 1.27, 95% CI 1.14-1.42) and CP (HR 1.26, 95% CI 1.15-1.39) were associated with higher risk. Trajectory analyses showed that persistently low SES, higher NCDS, and elevated CP were linked to increased dementia risk (HR ranges: 1.37-3.66, 1.31-3.00, and 2.05-5.85, respectively). The most unfavorable joint trajectory, characterized by low SES combined with high NCDS and CP, was also associated with elevated risk (HR 1.34-3.22). Results were robust in lagged analyses. CONCLUSION: SES, NCDS, and CP influence dementia risk independently and through combined long-term patterns, underscoring the need for public health strategies that target social and health disadvantages to prevent dementia.