More than 55 million people worldwide have dementia, a number expected to nearly triple by 2050. Deaths from strokes may double by the same year, and 10 per cent to 20 per cent of adults experience depression later in life.
While the numbers are striking, there’s a growing body of evidence showing that many of these cases may not be genetically fated, but rather could be delayed or prevented altogether by addressing health factors generally within our control.
At least 17 factors contribute to dementia, stroke and late-life depression, according to an extensive review published Wednesday in the Journal of Neurology, Neurosurgery, and Psychiatry.
Addressing the 17 factors can reduce people’s risk for all three conditions. Those factors are, in no order of importance:
- Blood pressure
- Body mass index
- Kidney disease
- Blood sugar
- Total cholesterol
- Alcohol use
- Diet
- Hearing loss or impairment
- Pain
- Physical activity
- Purpose in life
- Sleep
- Smoking
- Social engagement
- Stress
- Cognitive activity during leisure time
- Depressive symptoms
“This study just really shows how powerful lifestyle and behavioral changes are for age-related brain diseases,” said senior study author Dr. Sanjula Singh, an instructor in neurology at Harvard Medical School and principal investigator at the Brain Care Labs at Massachusetts General Hospital.
“Ultimately, we hope that people feel like there’s a hopeful message in here — that there are actually so many things that you can work on, and then not only your risk of stroke is lower, but also of dementia and/or of late-life depression,” Singh noted.
In the past, studies, tools or risk-prediction models have usually focused on these conditions individually. “From a human perspective, that doesn’t make a lot of sense,” Singh said.
Ideally, people wouldn’t want to develop any of these conditions, she added, so the research team wanted to find shared risk factors so people can essentially achieve multiple goals using the same tools.
Measuring the impact of lifestyle
The authors reviewed 59 meta-analyses — syntheses of data from multiple similar studies — that were published between 2000 and 2023 and had investigated the effects of modifiable risk factors on stroke, dementia and/or late-life depression among adults who weren’t previously diagnosed with these conditions.
All 17 factors were shared by at least two of the conditions, but there were no meta-analyses on relationships between late-life depression and 11 of the health measures: alcohol intake, BMI, blood sugar, cognitive activity, diet, hearing loss, kidney function, pain, physical activity, social engagement and stress, according to the study.
Of all the measures, blood pressure had the biggest impact. A normal blood pressure level is below 120 over 80 millimetres of mercury, or mm Hg. People with a level of 140/90 mm Hg or greater were more than twice as likely to have a stroke, 20 per cent more likely to develop dementia and 16 per cent more likely to experience depression.
Other top influential factors were smoking, sleep, physical activity and blood sugar.
“Grouping these all together is important, because I think different people derive different levels of motivation to make a behavior change” based on their personal concerns, such as a family history of dementia, stroke or depression, said Dr. Richard Isaacson, preventive neurologist and director of research at the Institute for Neurodegenerative Diseases in Florida. Isaacson wasn’t involved in the study.
“Data studies like this can help empower people to make meaningful changes in their day-to-day lives,” Isaacson added.
Lowering risk for age-related brain diseases
If 17 items seem overwhelming, look at it as a menu from which you can choose a few items — and work your way through the list over time, Singh said. But also know these factors overlap, she said — if you’re improving your diet and exercise, for example, you’re probably improving several things on that list, including blood pressure, blood sugar, sleep and cholesterol.
Not sure what to choose? Here’s how you can address what experts said are some of the most important determinants of dementia, stroke and depression.
Lowering high blood pressure: High blood pressure means less blood flow to the brain, which has a direct relationship with stroke and dementia, but is also associated with depression by way of reducing neurotransmitters in the brain, Isaacson said.
To address high blood pressure, you can have your level checked by a machine at a drugstore, a doctor or a home device, experts said. Lowering salt intake and getting enough potassium are important for reducing blood pressure, as well as exercising, losing excess weight, managing stress and seeing a sleep specialist if you have sleep apnea. A doctor can determine whether you also need medication.
Stop smoking: If you smoke, there are five actions you can take right now to quit, which concern identifying your triggers, learning from relapses, using helplines and apps, and speaking with doctors who can help you devise a treatment plan.
Improve your fitness: For physical activity, know that any amount is better than none — and the World Health Organization has guidelines for the type, frequency and duration of exercise you need depending on your age.
Get enough sleep: Older adults need at least seven hours of sleep nightly. You can help ensure a good night’s rest by keeping your room cool, quiet and dark; not drinking alcohol or caffeine in the several hours before bed; limiting screen time at night; and having a bedtime routine.
Regulate your blood sugar: Exercise, weight management and a healthy diet that limits refined carbohydrates and added sugars can also maintain healthy blood sugar levels.
The findings from the latest study inform the existing Brain Care Score, which was developed in 2023 at the McCance Center for Brain Health at Massachusetts General Hospital to help people gauge and manage their risk for dementia or stroke without medical procedures.
The 21-point score refers to how a person fares on 12 health-related factors concerning physical, lifestyle and social-emotional components of health. To this list, the new study adds pain, depressive symptoms, hearing loss, cognitive activity and kidney disease.
Researchers behind the score anticipate an updated version will be published later this year. For now, you can take the current edition here.
By Kristen Rogers, CNN
