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Men at risk for heart disease may develop dementia up to a decade earlier than similarly at-risk women, a new study found.
“The influence of cardiovascular disease on dementia in men a decade before the females is not known before,” said lead study author Dr. Paul Edison, professor of neuroscience at Imperial College London, in an email.
“This is novel finding with significant health implications.”
Cardiovascular diseases are the leading cause of death in the world, according to the World Health Organization, and heart disease has been the No. 1 killer in the United States for more than 100 years.
Heart disease risk factors include obesity, diabetes, high blood pressure and cholesterol, along with smoking, drinking too much alcohol and not getting proper exercise and adequate sleep, according to the US Centers for Disease Control and Prevention. All these conditions can lead to small vessel disease, which can affect oxygen delivery to the brain.
The damaging impact of cardiovascular risk was just as evident in people who didn’t carry the APOE ε4 gene as those who did carry the gene, the study found. The APOE ε4 gene is considered the strongest risk factor for the future development of Alzheimer’s disease in people over the age of 65. Having one or even two copies of the gene does not guarantee that Alzheimer’s will develop, experts say, so maintaining a healthy lifestyle may be critically important.
“Modifying cardiovascular risk may prevent Alzheimer’s disease,” said Edison, who is also the head of the Memory Research Centre at Imperial College London. “Our results suggest that this should be done a decade earlier in males than in females irrespective of whether they carry the risk genes (APOE ε4) for Alzheimer’s disease.”
The study’s findings are consistent with existing literature that shows higher levels of cardiovascular risk may be associated with negative neurocognitive outcomes, said epidemiologist Jingkai Wei, an assistant professor of family medicine at the University of Texas Health Science Center at Houston, in an email.
Wei, who was not involved in the new study, did similar research and found a decade of living with heart risk was linked to poor performance on cognitive tests measuring executive function, processing speed and immediate and delayed memory in men and women over 60.
The new study’s results supplement his own and suggest “poorer cardiovascular health is associated with both poorer cognitive function and brain pathology, which are both predictive of dementia,” Wei said.
Belly and body fat boosts risk
The study, published Tuesday in the Journal of Neurology, Neurosurgery & Psychiatry, looked at data on more than 34,000 men and women ages 45 to 82 who provided abdominal and brain scans to the UK Biobank, a longitudinal health study based in the UK.
Some participants also underwent a neuroimaging technique called voxel-based morphometry, or VBM, to identify the influence of abdominal and visceral fat, which surrounds the body’s organs, on brain neurodegeneration.
“The use of VBM did make the study’s findings more objective. Firstly, it avoids specifying regions of interests in advance. Instead, it will analyze the whole brain, which will make the results less biased,” Wei said.
Results showed that cardio risk factors — along with higher levels of abdominal and visceral fat — were associated with lower brain gray matter volume throughout the cerebral cortex in both men and women. Gray matter is responsible for processing and interpreting information, Edison said.
The most vulnerable regions of the brain, according to the study, were those involved in hearing, vision, emotional information processing and memory — all areas of the brain that are affected early in the development of dementia and Alzheimer’s disease.
When it comes to preventing cognitive decline from occurring, timing may be key, Wei said.
“Some observational studies have shown that midlife vascular risk factors, such as hypertension, high cholesterol, and obesity are associated with a higher risk of dementia, but not in late life,” Wei said.
“This suggests that midlife may be the key time window for development of dementia and therapeutic for prevention of dementia,” he added, “and addressing vascular risk factors from midlife could be an important approach for reducing the risk of dementia.”
As a result, it’s essential to start early and maintain a healthy lifestyle that reduces vascular risk factors throughout middle age, Wei said. That means controlling blood pressure, cholesterol and blood sugars, eating a healthy diet, staying physically active and quitting or avoiding heavy drinking and tobacco.
“Also, people may participate in activities that requires engagement of cognition. The key is to start all these proactive preventive actions early, and do not wait till late life,” he said.
The gender gap
Men appeared to be most susceptible to cardio risk factors between the ages of 55 and 74, while women were most susceptible a decade later, between 65 and 74, the study found. But why?
“There could be several reasons,” Wei said. “Existing research has shown that compared to women, men are more likely to have a poor profile of cardiovascular risk factors (hypertension, high cholesterol) in midlife, and the level has been sufficient to be linked to poorer brain health. Men may also be less likely to treat vascular risk factors.”
Differences in sex hormones can also play a role, Edison said. In men, testosterone is linked to higher levels of low-density lipoprotein, or LDL, and lower levels of high-density lipoprotein, or HDL, which increase the chances of having a heart attack.
“Men also have higher levels of hormones that cause inflammation and an increased chance of developing blood clots that may contribute to a higher chance of developing heart disease, as well as stroke,” Edison said.
Estrogen in women, however, “has protective effects, which reduces LDL levels while increasing HDL levels,” Edison said. “Following menopause, the risk of having heart problems begins to increase in women. The protective effect of estrogen pre-menopause may explain why women face problems a decade later than men.”
Men are also more likely than women to consume diets high in saturated fats, salt and red meat as well as use tobacco and alcohol more than women, Edison said. Then there’s the way men and women carry fat in their bodies.
“Men have more fat (buildup) lining the internal organs (visceral fat) while women have more fat around the hips (subcutaneous fat),” Edison said. “Visceral fat is linked to increased chances of having a heart attack.”
For all these reasons, men may need to be addressing cardio risk factors, body fat and overall weight earlier than women, he added.
“The influence of heart problems and being obese on brain cell degeneration is sustained and more apparent over twenty years in men than women,” Edison said. “Modify your diet and lifestyle to reduce the risk of developing heart problems and obesity; this will reduce the likelihood of developing dementia.”
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