Both men and women are at increasing risk for Alzheimer’s disease as they age. But women get it more often, and the disease doesn’t affect men and women the same.
Experts are studying Alzheimer’s differences between the sexes.
How Is Alzheimer’s Different in Men and Women?
In the U.S., 6.2 million people over the age of 65 have Alzheimer’s disease. About two-thirds of these people are women.
That means 1 in 6 women in this age group will develop the condition.
Experts have learned more about Alzheimer’s disease based on trends from other forms of dementia. For example, they found that dementia caused by things not related to Alzheimer’s isn’t more common in women than men.
One study found that men and women are equally as likely to develop non-Alzheimer’s dementia as they age. This means there’s a specific tie between Alzheimer’s disease and sex.
There are a few reasons why experts think it affects women more:
Women tend to live longer. The main reason women develop Alzheimer’s more than men is simply because women usually live longer. Women, on average, are likely to live 5 years more than men. Their life expectancy is 81 years, compared to 76 years for men.
Because age is the greatest risk factor for Alzheimer’s, the fact that women live longer means they’re more likely to develop it.
But this doesn’t explain entirely why more women have Alzheimer’s.
Even in studies of men and women of the same age, experts still found that women tend to develop Alzheimer’s more often.
Autoimmune disorders may play a role. Women are twice as likely as men to develop an autoimmune disease. Experts don’t know exactly why, but they've found that women tend to have a stronger immune system than men. Autoimmune disorders are often more common in pregnancy too.
Amyloid is a protein involved in Alzheimer’s. Researchers believe your body may release this protein to fight infections in your brain.
If this is the case, women probably have more amyloid buildup than men since they tend to have stronger immune systems. The higher amount of amyloid in women may be another reason why there are more cases of Alzheimer’s disease in women.
Different hormones in men and women. Experts know that the hormone estrogen can help protect your central nervous system. It can also help prevent diseases like Alzheimer’s. Estrogen can also help in the breakdown of amyloid.
When a woman goes through menopause, her estrogen levels go down. In fact, studies have found that older men may have higher levels of it than women do after menopause.
Some studies found that hormone replacement therapy (HRT) can help.
If a woman gets HRT soon after menopause, it may help lower the risk of Alzheimer’s disease. But other studies have shown no benefits to HRT for Alzheimer’s prevention, especially if HRT is started too late.
Also, HRT is linked to some complications like stroke, which can also heighten your risk of dementia. Experts need to look deeper into HRT’s side effects and effectiveness.
Pregnancy and its complications. In addition to a higher risk of autoimmune issues during pregnancy, there's also a higher risk of preeclampsia (high blood pressure during pregnancy). Experts have linked this condition, and other issues during pregnancy, to developing dementia later in life.
They need more research to understand how pregnancy-related issues might affect Alzheimer’s.
Your brain’s structure and how it functions. There are some slight differences in men and women’s brains.
Men tend to have a larger brain volume and more white matter, while women usually have more gray matter. Blood flow and connectivity might be higher in the parietal lobe of the female brain, while connectivity in the motor and visual areas may be higher in male brains.
This may impact how likely you are to develop Alzheimer’s.
These differences, especially the greater brain volume in men, may allow them to be more resistant to factors that lead to Alzheimer’s.
One study found that women are more likely to have atrophy, or a shrinkage of tissue, in a part of the brain called the hippocampus. This area of your brain plays a large role in memory.
Inflammation in your body. This may also play a role in your risk of Alzheimer’s.
If you’re a woman, your brain may respond differently to inflammation. This response could make you more likely to develop Alzheimer’s compared to a man.
Genetic differences between men and women. There are many genes that play a role in the development of Alzheimer’s.
One of them is called the APOE gene variant. Experts found that this gene may be a more relevant Alzheimer’s risk factor for women than men. If you’re a woman and have this gene variant, you’re more likely than a man with this gene to develop the disease.
Frailty. This term refers to a higher state of weakness compared to people of your own age. Women tend to have more frailty than men as they get older.
While women usually live longer than men, despite frailty, their higher level of overall weakness might put them at greater risk for Alzheimer’s. Other health problems related to frailty, like weight loss and exhaustion, are also risk factors for the disease.
Social factors that play a role. Higher income and education levels, career involvement, and more physical activity are factors that may help protect you from dementia.
In today’s older population, many women didn’t have the same opportunities as men in these areas. This may be linked to men having more cognitive reserve than women as they age.
This may mean that because some men had more success in these areas, they’re more likely to cope well with the mental decline that comes with age.