Does Marital Status Affect the Incidence of Dementia?

Age-related diseases such as dementia are on a rapid rise and offer a major challenge to the medical fraternity. Literature indicates that social relationships have been associated with the incidence of dementia. Numerous studies have shown that marriage is linked to better physical and psychological health for many adults. A prospective population-based study encompassing about two million individuals was conducted in Sweden in a cohort of young-old (50 to 64 years) and middle-old (65 to 74 years) to examine the association between marital status and dementia. Assessment of the risk of dementia among various marital status categories were done.

A total of 2 288 489 individuals, without prior dementia diagnosis at baseline participated in this study. Identification of dementia was done using the Swedish National Patient Register and the Cause of Death Register. One of the strengths of the study was that the authors were able to estimate the risk for various subcategories of unmarried individuals and also divide the sample according to gender and age groups mainly due to the large sample size.

The participants were classified into four categories:

• Married
• Single
• Divorced
• Widowed.

Time to event was estimated from the time of enrollment in the study until the time of dementia diagnosis, of being lost to follow-up, death or date of final follow-up, whichever event came first. The study had a follow-up period of up to 10 years.

Cox's proportional hazard regression models were used to analyze the relation between marital status and dementia. Two models were used to adjust for multiple covariates; model 1: adjusted for age and gender and model 2: additionally adjusted for having adult children, education, income and prior cardiovascular disease.

Observations

• During the follow-up period, a total of 31 572 individuals were found to be demented; dementia diagnoses were recorded for 5850 individuals in the young-old group and for 25 722 individuals in the middle-old group.
• It was also seen that non-married category had a significantly higher risk of dementia relative to the married category. Among the non-married participants, the highest risk of dementia was found in the divorced group (HR 2.05, 95% CI 1.91 to 2.21) as well as the single group (1.91, 1.79 to 2.03). The widowed category demonstrated a slightly lower risk dementia 1.38 (1.23 to 1.54)
• In the middle-old group (model 1), the category of participants in the non-married group showed a significantly higher risk of dementia when compared to the married group. In this group the highest risk of dementia was seen in divorced individuals.
• Gender specific estimates in the young-old group indicate divorced men to have a higher risk of dementia as against divorced women (HRs 2.1 vs 1.7, only-age adjusted model). However, in the fully adjusted model, no significant difference was found between male and female participants.

Conclusion

• It was seen that unmarried people have an increased occurrence of dementia as compared to their married counterparts.
• The results also demonstrated that marital status had a slightly higher risk for early-onset dementia.
• Unlike previous studies, this study found lower risk of dementia in the widowed group as compared to other non-married categories, however the authors felt that the risk ratios could possibly have been underestimated.

Limitations of the study

• The dementia diagnosis used in this study is based on information provided by national registers such as Swedish National Patient and the Cause of Death Registers, which in previous studies have shown to have high specificity but lower sensitivity for dementia identification.
• Dementia occurs in various subtypes, which has not been taken into account or provided by the national registers
• Underreporting and misclassification of the marital status could possibly lead to biased estimates.
• Since time in the respective marital statuses were unavailable, it could have affected the outcome of the study.

The authors are of the opinion that more studies are required to fully understand the relationship between marital status and dementia.

References:

1. http://bmjopen.bmj.com/content/6/1/e008565.full?g=w_jnnp_open_tab

2. http://www.nhs.uk/news/2009/07July/Pages/Maritalstatusanddementiarisk.aspx

Source-Medindia