- When one spouse is diagnosed with dementia, the other partner's risk increases by about 70% (74% for wives, 69% for husbands).
- The pattern holds across dementia types, including Alzheimer's and vascular dementia, and is similar for women and men.
- Spouses with lower incomes and fewer children face the widest gaps in absolute risk, likely due to thinner caregiving support.
- The study followed nearly a million married people in Taiwan using a national health insurance database.
- Five-year absolute risk differences: women saw a 2.75 percentage point increase (6.5% vs. 3.7%), men a 3.49 percentage point increase (9.2% vs. 5.75%).
- Younger spouses (under 55) had a higher relative risk, possibly due to shared vulnerabilities and caregiving stress.
- Possible causes include shared lifestyles, environments, and the strain of caregiving, leading to stress, sleep loss, and depression.
- The findings suggest dementia should be treated as a family matter, with closer monitoring and support for the caregiving spouse.