For many years, the medical community assumed that women and men contracted Alzheimer’s Disease (AD) at similar rates. They knew that more elderly women than men had the problem, but they simply assumed that the reason was that women lived longer than men.
Certainly, age is one of the strongest correlations for contracting AD, but it’s not the only one. Recent evidence suggests there are six biological reasons why Alzheimer’s poses a more serious risk to women’s health more than to men’s health.
Read More »Though scientists now know that age is not the primary reason why women suffer from Alzheimer more often than men, they also understand it is ONE of the reasons. Since women live four to five more years than men on average, age does play a role.
Living longer makes it more likely you will get AD, that much is clear. But, research shows that by age 65, 1 in 5 women contract Alzheimer’s. Meanwhile, only 1 in 11 men will show signs of the condition.
There’s more going on here than pure age.
2. Apolipoprotein E
One of the more recent breakthroughs with understanding Alzheimer’s is genetic research into the biology of lipids (fats). The human body produces four different types of Apolipoprotein E, which plays a major role in Alzheimer’s. Of the four types, which are often shortened to apoE1, apoE2, apoE3, and apoE4 in medical literature, apoE4 is the most interesting.
Both men and women who have the gene that codes for Alipoprotein E4 are more likely to develop late onset AD. However, the rates are wildly different. Women with the apoE4 gene (called apoE4 carriers) are twice as likely to develop AD than women without this gene. Men with the apoE4 gene are only slightly more likely to develop AD.
Clinical research is unclear on the reasons for this difference. Most presume it has something to do with hormones, but the picture is unclear. For example, women who do not carry the apoE4 gene show LESS AD if they take hormone replacement therapy (HRT). But, women with the apoE4 gene who use HRT are MORE likely to show AD.
Alternatively, researchers generally believe that women and men who express the apoE2 gene enjoy a protective effect against AD.
The bottom line is that many biologists believe that the apoE4 gene is the biggest genetic reason why women are more likely than men to contract Alzheimer’s.
3. Estrogen
Aside from estrogen’s effects on apoE4, research suggests that estrogen also affects the mitochondria in the brains of female rats. Mitochondria are the “energy factories” of the cell that helps convert glucose into ATP, the primary form of energy that the body uses to fuel its operations.
In female rats, contracting AD correlates with loss of mitochondria function in the brain.
In young female rats, estrogen seems to protect the mitochondria from “oxidative stress.” Though you cannot survive without oxygen, it also is a highly-reactive substance in the body that can cause mutations. Since mitochondria use oxygen to convert glucose into ATP, they’re often exposed to high levels of O2.
When estrogen levels decline in older female rats, there’s nothing to protect the mitochondria. This fact suggests that the mitochondria in older females get damaged by 02 and they suffer from lack of energy in the brain.
Yet, why female mitochondria would need the protective effects of estrogen more than mitochondria of male brains isn’t clear.
4. Stress
Stress is a well-known risk factor for contracting AD in both women and men. However, far more elderly women act as caregivers than elderly men.
This behavior difference puts women at higher risk of contracting AD. Emotions caused by receiving care can also play a role. Research shows that women react differently than men when they receive elder care. Women will go through emotional conflict that the literature describes as “grateful guilt.”
As a result, both sides of the caregiving equation seems to work against women. Women are both more likely to become a caregiver, and suffer more stress from receiving care. Part of this effect could by mollified by psychological care and working on changing cultural expectations that surround gender.
5. Early Signs of Alzheimer’s Is Harder to Spot in Women
Many of the cognitive tests that doctors use to identify AD depend on verbal interaction. In essence, doctors identify ALzheimer’s by asking a battery of questions to patients.
Yet, women are much more skilled communicators than men on average. For example, women buy 70% of the books bought in the United States. However, this communication ability can disguise early Alzheimer’s by making an early-onset female AD patient appear to be healthy.
Early treatment can slow down Alzheimer’s progression. This inability to spot the problem in women in the early stages suggests that they suffer more in the end.
6. Heart Disease and Diabetes
Cardiac and circulatory problems are well-known risk factors for developing Alzheimer’s. Yet, these circulatory problems impact women differently than men. Far more men suffer from cardiac problems, heart attacks, and stroke than women.
This difference creates what statisticians call a “selection bias.” More women will reach age 65 with AD because many of the men with the problem have been eliminated by stroke or cardiac problems.
Type 2 diabetes also could create a similar statistical bias. Twice as many men contract Type 2 diabetes than women, and diabetes shortens life expectancy. Diabetes likely removes more male AD patients from the population than women by age 65.
Role of Fitness in Alzheimer’s
However, the news isn’t all bleak for women with respect to contracting AD. Exercise plays a massive role in preventing Alzheimer’s. Research shows that women who show high fitness levels reduce their risk of contracting AD by 88% compared to women with moderate levels.
The good news here is that women can do something to prevent Alzheimer’s. Regular exercise can reduce a woman’s Alzheimer’s risk close to male levels
