Roughly 45% of dementia cases could be prevented or delayed by tackling 14 modifiable risk factors across life. That is the headline finding of the 2024 report from the Lancet Commission on Dementia Prevention, Intervention and Care.
The number is a population-level estimate, not a personal promise. But it shows how much of the disease burden traces back to conditions that medicine and everyday habits can influence.
The 14 factors, from childhood to old age
The Commission groups the risks by life stage. In early life, the single factor is not completing secondary education.
In midlife, roughly ages 18 to 65, ten factors appear. They are hearing loss, high blood pressure, smoking, obesity, physical inactivity, type 2 diabetes, depression, excessive alcohol, traumatic brain injury and high LDL cholesterol.
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In late life, three more come into play. They are social isolation, air pollution and untreated vision loss.
Two of the factors were newly added in the 2024 update. High midlife LDL cholesterol is estimated to contribute about 7% of dementia risk, and untreated vision loss in later life about 2%. The other twelve carried over from the Commission's 2020 report.
Who is behind the estimate
The Commission is led by Professor Gill Livingston of University College London. Her group's reports in 2017, 2020 and 2024 have pushed prevention toward the center of dementia policy.
Their argument is that risk reduction should sit alongside treatment, rather than begin only at diagnosis.
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The 45% figure carries important caveats. It assumes all 14 factors are eliminated across a whole population, which is not realistic in practice. Observational studies also cannot prove that changing a single habit will directly change an individual's outcome.
The authors describe the number as the theoretical ceiling of what is modifiable, not a guarantee.
The evidence that lifestyle changes actually help
Stronger evidence that structured lifestyle changes can protect thinking comes from a family of trials modeled on Finland's FINGER study. At the Alzheimer's Association International Conference 2026, researchers reported two-year results from LatAm FINGERS.
The trial enrolled more than 1,000 older adults across 11 Latin American countries. Participants who received structured coaching in physical activity, diet, cognitive training, social engagement and heart health monitoring showed 55% greater improvement in memory, thinking and reasoning than those following a self-guided program.
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The results were published simultaneously in a Lancet journal.
What it means day to day
The practical message from the Commission and the FINGER trials is consistent. Treating high blood pressure and high cholesterol, staying physically active, protecting hearing and vision, avoiding tobacco, moderating alcohol, staying socially connected and addressing depression have the strongest evidence behind them.
None of this replaces medical care. Anyone worried about their memory, or a family member's, should raise it with a doctor rather than self-diagnose or self-treat.
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