Multimorbidity burden and developmental trajectory in relation to later-life dementia: A prospective study.

INTRODUCTION: This study assessed the associations of multimorbidity burden and its developmental trajectory with later-life dementia.

METHODS: Among 5923 Health and Retirement Study participants, major chronic conditions including hypertension, diabetes mellitus, cancer, lung diseases, heart disease, stroke, psychological disorders, and arthritis were self- or proxy-reported in 1994-2008. Dementia diagnosis was self- or proxy-reported in 2008-2018. We used Cox regression to assess the associations of multimorbidity with incident dementia.

RESULTS: During follow-up (median = 8 years), 701 participants developed dementia. Each additional chronic condition in 2008 was related to 15% (confidence interval: 9% to 22%) higher hazard of dementia. Multimorbidity trajectories in 1994-2008 were classified as "rapid growth", "steady growth", "slow growth", and "no new condition" by the group-based trajectory modelling methods. Compared to "no new condition", the "rapid growth" trajectory was related to 32% (3% to 69%) higher dementia risk.

CONCLUSIONS: Both multimorbidity burden and its developmental trajectory were prospectively associated with risk of dementia.