Marital histories on risk of mild cognitive impairment and dementia

Abstract Background Earlier studies suggest being married later in life protects against dementia, while being single increases the risk. This study examines midlife marital status trajectories and their association with dementia and mild cognitive impairment (MCI) at age 70 plus in Norway. Methods We used a population sample from the Trondelag Health Study (HUNT) linked to registries (N = 8706) and applied multinomial logistic regression to examine associations between six marital trajectories (unmarried, continuously divorced, intermittently divorced, widowed, continuously married, intermittently married) from ages 44 to 68, and dementia or MCI diagnosis after age 70. We adjusted for education, number of children, smoking, hypertension, obesity, physical inactivity, diabetes, mental distress, and lack of close friends. Inverse probability weighting and multiple imputations were applied to account for selection bias. Results 11.6% of participants were diagnosed with dementia and 35.3% with MCI. Dementia prevalence was lowest among the continuously married (11.2%). Adjusting for confounders, the dementia relative risk ratio (RRR) was higher for the unmarried (RRR = 1.73; 95% CI: 1.24, 2.40), continuously divorced (RRR = 1.66; 95% CI: 1.14, 2.43), and intermittently divorced (RRR = 1.50; 95% CI: 1.09, 2.06) compared to the continuously married. Marital trajectory was less associated with MCI than dementia. Discussion Staying married in midlife is associated with a lower risk of dementia, and divorced individuals account for a significant share of dementia cases.