Lifestyle changes may lower dementia risk by about 25%

A PLOS One analysis of 69 studies involving nearly 3 million people found links between regular physical activity, about seven hours of sleep, and lower late-life dementia risk, while long periods of sitting were associated with higher risk; the combined lifestyle changes were estimated to reduce average late-onset dementia risk from about 11% to about 8%.

A pooled analysis published in PLOS One examined how sleep, physical activity and sedentary behavior relate to dementia risk later in life. Researchers combined data from 69 studies that together included nearly 3 million people, mostly living in high-income countries, with an average participant age of about 67. The studies measured habits beginning around age 35 and followed people for between one and 11 years. The authors reported that simple lifestyle differences could be associated with a roughly 25% relative decrease in risk of late-onset dementia. Key findings: - The analysis compiled 69 studies and nearly 3 million participants from high-income countries; the average age across studies was about 67 and follow-up ranged from one to 11 years. - The pooled estimate suggested that combined lifestyle changes could lower average late-onset dementia risk from about 11% to about 8%, a relative reduction near 25%. - Sleep results indicated a “sweet spot” of about seven to eight hours per night; sleeping less than seven hours was associated with an 18% higher dementia risk and sleeping more than eight hours was associated with a 28% higher risk. - Sedentary time and activity findings showed that sitting more than eight hours per day was linked with almost a 30% higher dementia risk, while regular physical activity, including everyday walking, was associated with about a 25% lower risk; breaking up long sitting periods produced notable benefits. - Commentators and the study authors cited possible biological pathways including increased brain-derived neurotrophic factor (BDNF) with movement, reduced beta-amyloid, lower chronic brain inflammation, and sleep-related glymphatic clearance of waste. Summary: The analysis links regular moderate activity and about seven to eight hours of sleep with lower late-onset dementia risk and identifies prolonged sitting as a factor associated with higher risk. Undetermined at this time.