Background Being married is associated with healthier lifestyle behaviours and lower mortality and may reduce risk for dementia due to life-course factors. We conducted a systematic review and meta-analysis of studies of the association between marital status and the risk of developing dementia.
Methods We searched medical databases and contacted experts in the field for relevant studies reporting the relationship, adjusted for age and sex, between marital status and dementia. We rated methodological quality and conducted random-effects meta-analyses to summarise relative risks of being widowed, divorced or lifelong single, compared with being married. Secondary stratified analyses with meta-regression examined the impact of clinical and social context and study methodology on findings.
Results We included 15 studies with 812 047 participants. Compared with those who are married, lifelong single (relative risk=1.42 (95% CI 1.07 to 1.90)) and widowed (1.20 (1.02 to 1.41)) people have elevated risk of dementia. We did not find an association in divorced people.
Further analyses showed that less education partially confounds the risk in widowhood and worse physical health the elevated risk in lifelong single people. Compared with studies that used clinical registers for ascertaining dementia diagnoses, those which clinically examined all participants found higher risk for being unmarried.
Conclusions Being married is associated with reduced risk of dementia than widowed and lifelong single people, who are also underdiagnosed in routine clinical practice. Dementia prevention in unmarried people should focus on education and physical health and should consider the possible effect of social engagement as a modifiable risk factor.
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Contributors AS, AS-M, GL and GL conceived and designed the study. AS conducted the literature search. AS and JR assessed manuscripts for inclusion in the study and rated them for quality. AS extracted data and performed analyses. All authors contributed substantially to drafting the article and revising it critically for intellectual content and gave final approval to the submitted manuscript.
Funding AS received funding from the Wellcome Trust (200163/Z/15/Z) during the conduct of the submitted work. AS, GL and GL are supported by the UCLH NIHR Biomedical Research Centre. The authors analysed results and prepared this manuscript independently of the funding body. The views and opinions expressed therein are those of the authors and do not necessarily reflect those of the Wellcome Trust or NIHR. Funders had no role in the study design and the collection, analysis and interpretation of data and the writing of the article and the decision to submit it for publication. The researchers were independent from funders and sponsors. All researchers could access all the data.
Competing interests None declared.
Provenance and peer review Not commissioned; externally peer reviewed.