Your husband (or wife) may increase your risk of dementia by up to 70%

Could your spouse’s dementia be contagious?

Being married has been shown to help sustain many aspects of health. Married people with heart disease are less likely to have a heart attack or die from cardiovascular disease, they have a lower risk of obesity and they’re also likely to live longer.

But the story is actually a bit more complicated. A new study showed that those who were married to someone with dementia had a higher chance of developing dementia themselves, compared to married couples where neither dealt with dementia.

It’s a significant increase in risk — up to 74% in women, and 69% in men.

This builds on research from last year that showed widowed, divorced or never-married folks had a lower risk of dementia compared to people who were married. It suggests that people build their own social networks after their partner dies, or after divorce — and if they were never married, they have more time and energy to build those bonds.

But how exactly can a marriage that provides love, support and that spice of life hurt the health of your brain? Researchers have a few theories.

If your spouse has dementia, your risk increases

The study, published Monday, looked at nearly 1 million married people in Taiwan. Researchers found that people with spouses who had dementia had a higher risk of developing the same symptoms, compared to married couples that weren’t dealing with dementia.

Dementia is not a disease in itself, it’s a broad category of symptoms that encompass decline in cognitive abilities, like memory, language, and problem solving.

In this study, dementia from all causes were considered, including Alzheimer’s (abnormal protein formation) and vascular dementia (disrupted blood flow to the brain).

This was seen across both sexes and diverse neighborhood settings (urban, suburban and rural).

Interestingly, though the association was still present, those with higher income and more children were slightly less likely to develop to dementia.

Why can one spouse increase dementia risk in the other?

Researchers suggest there may be a couple things at play, including forces set in motion long before dementia ever sets in.

First, they point to assortive mating. This is the idea that people select partners who have a similar education, socioeconomic status and health behaviors.

Higher education, higher income, a healthy diet and regular exercise all lower risk or delay dementia. These are all early life factors that play a role in dementia later in life.

Then, there’s a life together. Couples share habits, possibly over many years, like diet, exercise and socioeconomic conditions, which all affect cognitive aging.

It’s possible that if one person develops dementia, their spouse develops dementia in part because of a lifetime of the same living conditions.

But researchers say neither of these two factors are enough to fully explain their findings. That’s because the correlation between one spouse developing dementia and the other one developing it too happens across groups — so the richest, healthiest, most educated folks are also affected by this phenomenon.

Lastly, they point to the burden of caregiving. When one spouse is dealing with dementia, the other might be the first one to step in to care for them.

As many as a third of caregivers are doing this while dealing with poor health themselves. They are often unpaid and receive little support.

Caregivers must contend with high risk of depression, stress, constant frustration, anger, and guilt. This can lead to dependence on drugs and alcohol. All this heightens risk of dementia.

The study showed a small difference in women vs. men in spouses without children — suggesting that when no children are available to help, the burden is placed on the wife.