A long-term study by researchers from East Asia has shown that dementia in one spouse is associated with an increased risk of developing the disease in the other partner. This does not refer to infection in the literal sense — the disease is not transmitted like an infection. The study analyzed data from over 950,000 individuals. Of these, more than 190,000 lived with a spouse diagnosed with dementia. The medical records of participants were examined over the period from 1998 to 2022, taking into account age, gender, income level, place of residence, health status, and family history. The results showed that women whose partners suffered from dementia had a 74% higher risk of developing the disease compared to women whose spouses were healthy. For men, this figure increased by 69%. Over five years of observation, dementia was diagnosed in 6.5% of women whose husbands fell ill, compared to 3.7% among other participants. For men, the figures were 9.2% and 5.8%, respectively. Researchers believe that the issue is not only related to a similar lifestyle. People often choose partners with similar habits, education levels, incomes, health attitudes, and even cognitive reserves. This phenomenon is called assortative mating. Moreover, spouses live in the same conditions for decades, follow similar diets, have comparable levels of physical activity, and are exposed to the same environmental influences. Another important factor is chronic stress. Caring for a person with dementia is often accompanied by emotional exhaustion, sleep disturbances, social isolation, and deterioration of one’s own habits, which can also negatively impact brain health. At the same time, the authors of the study emphasize that the identified connection does not prove that one spouse's dementia directly causes the disease in the other. Most likely, the increased risk is explained by a combination of common factors and prolonged stress. The study showed that spouses of people with dementia are in a high-risk group. Therefore, doctors recommend paying attention not only to the patient but also to the person caring for them — taking care of sleep, physical activity, nutrition, and seeking medical help promptly at the first signs of memory or cognitive function deterioration.