Dementia in immigrant groups: A cohort study of all adults 45 years of age and older in Sweden

Objective: To study the association between country of birth and incident dementia in several immigrant groups in Sweden. Methods: The study population included all adults (n = 3,286,624) aged 45 years and older in Sweden. Dementia was defined as having at least one registered diagnosis of dementia in the National Patient Register. The incidence of dementia in different immigrant groups, using Swedish-born as referents, was assessed by Cox regression, expressed in hazard ratios (HRs) and 95% confidence intervals (CI). All models were stratified by sex and adjusted for age, geographical residence in Sweden, educational level, marital status, and neighbourhood socioeconomic status. Results: A total of 136,713 individuals had a registered dementia event, i.e. 4.2%; 3.6% among men and 4.9% among women. After adjusting for confounders, in general, there was a lower incidence of dementia among both male immigrants (HR 0.85, 0.83–0.88) and female immigrants (HR 0.93, 0.91–0.95) compared to their Swedish-born counterparts. Among immigrant groups, a higher incidence (HR, 95%CI) of dementia was observed among men from Finland (1.14, 1.08–1.20), Bosnia (1.61, 1.18–2.20), Estonia (1.25, 1.10–1.43) and Russia (1.37, 1.12–1.69), and women from Finland (1.20 1.15–1.24) and Norway (1.14, 1.07–1.22). Conclusions: Risk of dementia was lower in immigrants in general compared to the Swedish-born population; however there were substantial differences among immigrant groups in risk of dementia. Developing dementia in a new country with a different language could cause problems for both patients and the health care staff.