Four Everyday Habits That May Shape Dementia Risk

A set of recent studies suggests dementia risk is influenced not just by age, but by a mix of daily habits, including how long people sit, what they eat, how optimistic they are, and whether they feel socially connected. The article argues that brain health is shaped over time by physical, mental, nutritional, and social factors working together.

A study from the University of York in Canada, published in PLOS One, reviewed dozens of cohort studies involving millions of participants and found that sitting more than eight hours a day was associated with about a 27% higher risk of dementia. Regular physical activity was linked to a 25% lower risk, while both too little sleep, under seven hours, and too much sleep, over eight hours, were associated with higher risk than sleeping 7 to 8 hours a night. Researchers stressed these are statistical associations, not proof of causation.

Doctors quoted in the article said the message is broader than one habit. Dr. Galit Segal of Maccabi Health Services said sedentary behavior fits into a larger pattern of vascular risk, including high blood pressure, high cholesterol and diabetes, and noted that, "even if a person sits for many hours at work, the damage can be reduced through exercise later in the day." Dr. Tamara Shiner of Ichilov Medical Center said prevention requires a full lifestyle approach, including exercise, mental activity, social contact, good sleep, control of vascular risk factors, and stopping smoking. She also said exercise can slow the process, even if it cannot stop it entirely.

The mental-health section of the report cited a Journal of the American Geriatrics Society study of 9,071 people aged 70 and older. Over an average 6.7-year follow-up, 3,027 developed dementia, and higher optimism was associated with lower risk, including a 15% reduction per one standard-deviation increase and a 36% to 43% reduction in the most optimistic group versus the least optimistic. Separately, a Neurology study of 92,849 participants found plant-based diets were linked to lower dementia risk when the food was healthy, but higher risk when the diet relied on processed or sugary plant foods. A final study on loneliness found that older adults who felt lonelier had worse memory at baseline, though their decline over time was not faster than others.