“By modifying any one of the factors, you may reduce your risk of all three conditions, and there are many behavioral and lifestyle changes people can make to achieve this,” says the principal investigator Sanjula Singh, MD, PhD, a physician-scientist and epidemiologist with the Brain Care Labs at Massachusetts General Hospital in Boston.
These are the 17 risk factors, in no particular order:
- Blood pressure
- Kidney disease
- Body mass index (BMI)
- Blood sugar
- Alcohol use
- Total cholesterol
- Diet
- Pain
- Hearing loss or impairment
- Physical activity
- Purpose in life
- Sleep
- Smoking
- Social engagement
- Stress
- Cognitive activity
- Depressive symptoms
New Scientific Review Builds on Reams of Earlier Data
To arrive at this list, Dr. Singh and her team analyzed data from 59 previous studies. Each of those studies was itself a meta-analysis, based on an examination of data from a number of other prior independent studies.
Singh and her collaborators estimated that improvements to modifiable risk factors could prevent or slow at least 60 percent of strokes, 40 percent of dementia cases, and 35 percent of late-life depression cases.
The ultimate goal of identifying these risk factors, according to Singh, is “to help people take better care of their brains.” She says the results raise the question, “What are things that everybody can do on a daily basis that lower risk for not only dementia and stroke, but also late-life depression?”
High Blood Pressure Has the Biggest Impact on Brain Health as We Age
When assessing the 17 modifiable risk factors, high blood pressure (hypertension) emerged as the one with the biggest impact.
“The finding emphasizes that taking care of your blood pressure is one of the best things you can do for your brain,” says Singh.
That result was no surprise, according to Mitchell Elkind, MD, the chief clinical science officer at the American Heart Association. “Hypertension is the biggest risk factor for stroke,” says Dr. Elkind, who was not involved in the study. High blood pressure is responsible for about 50 percent of ischemic strokes (caused by a blocked blood vessel) and up to 80 percent of hemorrhagic strokes (caused by the rupture of a blood vessel in the brain), he explains.
“Growing evidence suggests that injury to the brain from stroke can lead to secondary neurodegeneration, inflammation, and blood brain barrier leakage that contribute to cognitive loss and dementia,” Elkind says.
Kidney Disease, Smoking, and Hearing Loss Are Also Cause for Concern
Amanda Opaskar, MD, a clinical assistant professor in the division of vascular neurology at the Case Western Reserve University School of Medicine in Cleveland, flags tobacco use as another major risk factor among her patients.
“Some patients can appear really healthy with a normal BMI and good blood pressure, but then they exhibit stroke-like symptoms,” says Dr. Opaskar, who was not involved in the research. “Almost inevitably, their tobacco use is their main risk factor. Quitting smoking dramatically reduces the risk.”
Hearing loss is an underappreciated but very serious health concern, and linked more to dementia and depression than stroke, suggests Elkind.
“Hearing loss can lead to dementia and depression by limiting social connection or the input of information for the brain to process, leading to diminished neuronal activity,” he says. “People who can’t hear may become socially isolated and depressed, and without social interaction, their cognitive faculties decline.”
The Good News: You Have the Power to Lower These Risks
Singh urges people to use the list of 17 modifiable risk factors as a “menu,” from which they can choose factors to work on that best fit their lives.
“Exercise may not be feasible for you right now, for example, but maybe you can start to work on your dietary intake and eat more vegetables,” she says.
“Also, because a lot of these risk factors are interconnected, by working on one risk factor, you might actually improve a few others indirectly,” she notes.
The results do highlight exercise as a very significant factor to focus on. Plenty of previous research shows it provides a strong protective effect on health.
While this analysis is interpreted from a large body of prior research, it’s also limited because the findings are not directly determined from clinical trials following human participants. Opaskar underscores that the results indicate a link between the 17 risk factors and stroke, dementia, and depression — but they do not prove these factors cause age-related brain diseases.
3 Critical Ways to Keep the Brain Healthy
Are you motivated to make a change to improve your brain health? Consider these three important actions.
Opaskar advises people to choose exercise that they can tolerate: “If you have osteoarthritis or musculoskeletal pain, you can do low-impact activities like riding a recumbent bike or swimming.”
Keep the brain stimulated. “I was surprised by the relative impact of leisure-time cognitive activity on overall brain health [in this study],” says Elkind. Pursuits that may strengthen the brain include reading, playing music, pursuing hobbies, and doing puzzles. “These activities are like exercise for the brain, the way physical activity is exercise for the body and muscles,” he says.
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