What “45% preventable” actually means
The figure comes from the 2024 Lancet Commission on dementia prevention, intervention and care — one of the most authoritative reviews in the field. Its conclusion, in the Commission's own careful language, is that up to 45% of dementia cases could potentially be “delayed or reduced” by acting on 14 modifiable risk factors across a lifetime.
That phrasing matters. It does not say 45% of cases can be cured, or that any individual can guarantee they won't develop dementia. It's a population-level estimate of potential — what might be achievable across society if everyone optimized these factors. For you as one person, the honest translation is: a large share of dementia risk is movable, and the levers are ordinary.
The short version: risk is not fixed at birth. Age and genes matter, but roughly half of the population-level risk traces back to things you can influence — and most of them are the same habits that protect your heart.
The 14 modifiable risk factors
The 2020 Commission listed 12 factors; the 2024 update added two more — untreated vision loss and high LDL cholesterol. They fall into three natural groups.
The physical numbers
High blood pressure, diabetes (high blood sugar), obesity, high LDL cholesterol, and physical inactivity. These damage the small vessels that feed the brain — which is why what's good for your heart is good for your head. Blood pressure is the single most important; we cover it in depth in Blood Pressure and Brain Health.
Daily lifestyle
Smoking, excessive alcohol, and physical inactivity again. Quitting smoking helps at any age, and on brain measures, less alcohol is simply better. A brisk walk most days improves several factors at once.
Sensory and social
Hearing loss, untreated vision loss, social isolation, depression, less education (in early life), traumatic brain injury, and air pollution. Hearing loss is one of the largest single contributors — and hearing aids are one of the most under-used protective tools. Staying socially and mentally engaged builds what researchers call cognitive reserve.
The CDC and the Alzheimer's Association both echo the same practical list.
What you can't change — and why it isn't the whole story
Two big risk factors are outside your control: age (the strongest single factor) and genetics, including the APOE-e4 gene variant. This is real. But it's not destiny: studies consistently find that people at higher genetic risk still have lower dementia rates when they manage the modifiable factors. Genes load the gun; lifestyle influences whether the trigger is pulled — and how soon.
The highest-impact moves at each life stage
Midlife (roughly 40–65)
This is the highest-leverage window. Get blood pressure, blood sugar, and cholesterol checked and controlled; protect your hearing; stay active; don't smoke. Damage accumulated here shows up decades later.
Later life (65+)
It is never too late. Treating hearing and vision loss, staying socially connected, keeping active, and managing blood pressure all still lower risk after 65. The brain remains responsive.
🧠 See which factors you can act on
The Brain Health Score turns these factors into a 0–21 number in about two minutes — and shows you where to start. Free, nothing saved.
Get My Score →Where to start
Don't try to fix all 14 at once. Take a baseline with the free Brain Health Score, pick your one or two lowest-hanging factors, and give them a month. For the full habit-by-habit playbook, see How to Improve Brain Health: 12 Habits That Actually Matter. And because mental engagement builds cognitive reserve, keeping your mind active with puzzles — like the free daily ones at BrainDrop — is a pleasant complement to the medical factors.
Sources
- The Lancet — Dementia prevention, intervention and care: 2024 report of the Lancet standing Commission.
- Alzheimer's Disease International — summary of the 45% figure and 14 factors.
- CDC — Reducing risk of Alzheimer's disease.
- Alzheimer's Association — Causes and risk factors.