A genetic tendency for certain forms of high blood pressure and cholesterol is linked to a potential increased risk of Alzheimer’s disease, according to a new study.
The exact cause of Alzheimer’s disease is unclear, and although there are drugs to slow the progression of the disease, there is still no cure.
Scientists have been working to better understand Alzheimer’s disease in order to find ways to prevent or treat it.
Understanding cannot come soon enough. More than 6 million Americans currently have the disease, but the Alzheimer’s Association predicts that number will more than double by 2050, costing the country $1 trillion. Women and black or Hispanic people are disproportionately affected by the disease.
Researchers in the study, published Wednesday in the journal JAMA Network Open, were trying to understand modifiable risk factors that could prevent a person from developing Alzheimer’s disease. They also hoped to help guide drug development.
They analyzed data from the European Alzheimer & Dementia Biobank, a collection of DNA records from people with and without Alzheimer’s disease in 11 European countries. Genetic factors account for up to 70% of attributable risk in common forms of Alzheimer’s disease, according to the Biobank.
The new study included 39,106 people with clinically diagnosed Alzheimer’s disease and 401,577 controls who did not have the disease.
When researchers compared each other’s genetics, they found that people who had certain genes that resulted in higher levels of a type of cholesterol called high-density lipoprotein, also known as HDL or “good” cholesterol, had a slightly higher risk of developing Alzheimer’s. They found a similar increased risk for people who carry the genes responsible for higher systolic blood pressure.
The increase in Alzheimer’s risk was about 10% for each standard deviation increase in HDL cholesterol. And for every 10 millimeters of mercury (mm Hg) increase in systolic blood pressure, the risk of developing Alzheimer’s disease increases 1.22 times.
The study found no consistent evidence of genetic associations with other lipid traits, nor evidence that BMI, alcohol consumption, smoking or diabetes increased the risk of developing Alzheimer’s disease. .
Other studies looking only at lifestyle factors that involve obesity, alcohol, smoking, and diabetes — not the genetic risk of those factors — have shown a link between them and higher risk. of Alzheimer’s disease.
The researchers said it is important to note that although this was a large study, it cannot be generalized to the rest of the world as most of the participants were of European descent and from others may have different genetic factors for Alzheimer’s disease. The study also does not show that genes predetermine people with Alzheimer’s disease. More research needs to be done, scientists say.
Although the researchers can’t determine why this association may be a risk, they have some ideas.
For people with a genetic predisposition to higher HDL, it may be a balancing act. HDL is sometimes called “good” cholesterol because it helps the body get rid of “bad” cholesterol, LDL, which can clog arteries and prevent blood and oxygen from reaching the heart.
In heart health, higher HDL can help prevent stroke or heart attack. But for brain health, higher HDL can upset the balance of a particular type of protein that scientists believe plays a role in the development of dementia.
Other studies have shown that high blood pressure in midlife may be a risk factor for Alzheimer’s disease, although research is more limited on its effects later in life.
Dr. Sudha Seshadri, director of UT Health San Antonio’s Glenn Biggs Institute for Alzheimer’s disease and neurodegenerative diseases, said people should keep in mind that this is just ‘a study.
“Overall, I would say it offers some support that lower blood pressure can be good. And the fact that higher HDL raises concerns about dementia, but there are many explanations for this,” said Seshadri, who was not involved in this research.
She said it could be something as simple as higher HDL protecting people from heart attack or stroke, helping them live longer, and age is a factor. dementia.
“This is research that needs to be replicated and better understood. It is certainly interesting. But that’s just one piece of information,” Seshadri said.
Studies like this are good building blocks for understanding how the disease works, said Dr. Rebecca M. Edelmayer, senior director of science engagement for the Alzheimer’s Association.
It’s an exciting time in the field, she said, as researchers understand that cognitive decline or dementia is likely due to family history and genetics, but also to risk factors that can be changed. such as diet, heart health and exercise.
“As outlined in the article, we believe that a large proportion of dementia cases worldwide could potentially be prevented or delayed by targeting modifiable risk factors and also understanding how we disentangle what might be genetic and what could be related to modifiable risk,” said Edelmayer, who was not involved in the new research.
It would be helpful if more people signed up for clinical trials so that scientists could better understand the causes of Alzheimer’s disease.
Edelmayer believes that in the future, treating Alzheimer’s disease and potentially other dementias will require a combined approach to address modifiable risk factors as well as powerful treatments.
A powerful area to target is heart health.
“I would say the current population-level evidence suggests that the risk of cognitive decline and possibly dementia could be reduced, particularly by focusing on cardiovascular risk factors,” Edelmayer said.
Eating a healthy diet, exercising regularly, quitting smoking, and managing heart health and diabetes should all help.
“It’s really what’s good for your heart that’s going to be good for your brain,” she said.