A large-scale study published in the Journal of the American Medical Association (JAMA) has revealed that individuals whose spouses develop dementia face a significantly higher risk of receiving the same diagnosis themselves. According to research involving nearly 1 million married adults in Taiwan, this increased risk persists even after accounting for shared lifestyle factors, health profiles, and socioeconomic backgrounds.
Study Scope and Methodology
Researchers analyzed health care records from Taiwan’s national health insurance program, which covers approximately 99% of the population, spanning from 1998 to 2022. The study cohort included more than 190,000 individuals whose spouses received a new dementia diagnosis, compared against a control group of over 760,000 people who did not have dementia or a partner with the condition.
Participants were matched based on age, sex, income, and residential location. The analysis further adjusted for family size, medical conditions, and health care usage. By controlling for these variables, investigators sought to determine if the association between partners remained after accounting for the factors couples already share.
According to Medicalxpress, the results showed that women whose partners developed dementia had a 74% higher relative risk of developing the condition, while men saw a 69% increase.
Absolute Versus Relative Risk
While relative risk figures highlight a significant association, researchers emphasized the importance of absolute risk to provide a clearer picture of the actual probability. Over a five-year follow-up period:
- Among women: 6.5% of those with a partner diagnosed with dementia developed the condition, compared to 3.7% in the control group.
- Among men: 9.2% of those with a partner diagnosed with dementia developed the condition, compared to 5.8% in the control group.
Similar trends were observed when researchers examined Alzheimer’s disease and vascular dementia as separate categories.
Understanding the Mechanism
The study suggests that the phenomenon is not a result of dementia “passing” between partners, but rather a reflection of complex, overlapping factors. Co-author Dr. Chi-Shin Wu noted that the findings move beyond the traditional assumption that caregiving stress is the sole driver of the association.
Many were based on relatively small or regional samples [and] our study included spouses in general and did not assume that every spouse was the primary caregiver,
Dr. Chi-Shin told the ABC.
Researchers highlighted three primary factors that may contribute to these outcomes:
- Assortative Mating: The tendency for individuals to choose partners with similar education levels, socioeconomic backgrounds, and cognitive reserves.
- Shared Lifestyles: Couples often share long-term dietary habits, exercise patterns, and environmental exposures, which shape brain health over decades.
- Caregiving Dynamics: While not directly measured, the researchers acknowledged that being a primary caregiver can lead to chronic stress, sleep loss, and social isolation, which are recognized risk factors for dementia.
Socioeconomic Factors and Future Implications
The study also observed that the risk of dementia was lower for spouses who had higher incomes or more children.
Despite these findings, experts advise that spouses of people with dementia should be aware of the increased risk but not alarmed.
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