Preventing dementia: what is realistically possible

Dementia is the diagnosis many people over 50 fear most – and the one they feel most powerless against. That powerlessness is only partly justified. In 2024 the Lancet Commission on dementia prevention estimated that almost half of all dementia cases worldwide could, in theory, be prevented or delayed. The figure is often misread. This article sorts out what is well supported, what is plausible but unproven, and what is not worth your money.

The 14 risk factors – and what "45%" means

The Commission, led by psychiatrist Gill Livingston, added two factors in 2024: high LDL cholesterol (from midlife) and untreated vision loss (in later life). The other twelve are less education, hearing loss, high blood pressure, smoking, obesity, depression, physical inactivity, diabetes, heavy drinking, traumatic brain injury, air pollution and social isolation. Hearing loss and high LDL account for the largest shares, 7% each, followed by less education in childhood and social isolation in later life at 5% each; each remaining factor contributes between 1% and 3%.

These percentages are population attributable fractions: how many fewer cases a population would have if a risk factor vanished entirely – assuming the link is causal. The Commission corrected for overlap between factors and acknowledges that some associations may be only partly causal. For you personally, avoiding all 14 factors lowers risk but does not make you immune. Age and genes remain the strongest influences. Why relative figures are so easily overrated is explained in our piece on absolute versus relative risk.

Hearing loss: a big factor, little proof

Whether hearing aids lower dementia risk is unresolved. The key randomised trial, ACHIEVE (Lancet 2023), assigned 977 people aged 70 to 84 with hearing loss to either hearing aids or a health-education programme. After three years, cognitive decline overall did not differ. Only in a prespecified subgroup at higher baseline risk (238 participants from a long-running cohort study) was decline 48% slower. A subgroup does not prove an effect; it generates a hypothesis. Observational studies showing less dementia among hearing-aid users cannot rule out that these people are healthier and better cared for anyway.

Treating hearing loss is still worthwhile for quality of life and conversation. In Germany, an ear, nose and throat (ENT) specialist tests hearing and prescribes. Statutory health insurance (GKV, which covers most residents) pays up to a fixed amount; the co-payment is €10 per device, and pricier models cost extra.

Blood pressure: the strongest evidence

SPRINT MIND (JAMA 2019) treated 9,361 adults aged 50 or older with hypertension to a systolic target below 120 or below 140 mmHg. Intensive treatment reduced mild cognitive impairment: 14.6 versus 18.3 cases per 1,000 person-years (hazard ratio 0.81). For dementia alone, the difference – 7.2 versus 8.6 – was not statistically significant, partly because the trial stopped early.

The China Rural Hypertension Control Project (Nature Medicine 2025) enrolled 33,995 people aged 40 or older with uncontrolled hypertension in 326 villages. Where trained community health workers treated consistently to below 130/80 mmHg, systolic pressure fell 22 mmHg more over four years than with usual care, and dementia diagnoses were 15% less frequent (risk ratio 0.85). Serious adverse events were not more common. Caveats: the trial was open-label, and starting blood pressures were far higher than in most treated patients in Germany. The Commission recommends keeping systolic pressure at 130 mmHg or below from age 40. For measuring correctly, see home blood pressure measurement.

Lifestyle, metabolism, environment

• Exercise: active people develop dementia about 20% less often in observational studies. The Commission warns of reverse causation – people in cognitive decline move less. More in our piece on sitting.
• Smoking and alcohol: quitting pays at any age. The Commission lists heavy drinking as a risk; why "moderate" drinking does not protect either is explained here.
• Diabetes: earlier onset of type 2 diabetes means higher risk; intensive glucose control has not been shown to prevent dementia.
• LDL cholesterol: each 1 mmol/L higher LDL is associated with about 8% more dementia. But the Commission notes there are no long-term, high-quality statin trials for dementia prevention; trials in later life showed no effect. Statins are a cardiovascular drug – see statins for prevention.
• Depression, isolation, education: treat depression, keep up contacts, stay mentally active – plausible, mostly observational evidence.
• Head injury and air: wear a helmet for cycling and contact sports; clean air is largely a policy task.

Several levers at once: FINGER, POINTER and a reality check

The Finnish FINGER trial (Lancet 2015) combined diet, exercise, cognitive training and vascular risk management in 1,260 at-risk people aged 60 to 77. After two years, cognitive test scores were slightly but significantly better. The US POINTER trial (JAMA 2025) confirmed this in 2,111 people aged 60 to 79: a structured programme improved cognition more than a self-guided one, although both groups improved. Neither trial measured dementia cases.

Where dementia was the endpoint, success was elusive. In the Dutch preDIVA trial of 3,526 people aged 70 to 78, 7% developed dementia after almost seven years with or without nurse-led vascular care. The French MAPT trial (1,680 participants aged 70 or older) found no significant effect after three years – neither for the multidomain programme nor for omega-3 fatty acids. Perhaps at 70, with good routine care, the window is already too short.

What does not work

A Cochrane review of 28 trials with more than 83,000 cognitively healthy adults found no good evidence that vitamin or mineral supplements preserve thinking or prevent dementia; B vitamins probably had little or no effect, vitamin E none. Ginkgo did not prevent dementia in a large trial of 3,069 people aged 75 or older over about six years. Brain-training apps at best improve test scores briefly (Cochrane; low to very low certainty); a dementia benefit has never been shown. See also our piece on supplements.

Blood tests for Alzheimer markers such as p-tau217 and the new antibodies lecanemab and donanemab do not belong in prevention. The first guideline on these blood tests (Alzheimer's Association, 2025) is aimed at specialists evaluating people with cognitive symptoms. The EU approved lecanemab in April 2025 and donanemab in September 2025 – only for early symptomatic Alzheimer's disease with confirmed amyloid, and only for people carrying no or one copy of the risk gene ApoE4.

What you can do – by priority

1. Know and treat your blood pressure, aiming from age 40 for a systolic 130 mmHg or below, unless your doctor advises otherwise.
2. Do not smoke, and keep alcohol low.
3. Move – regularly, with endurance and strength components.
4. Have hearing and eyesight checked – and actually wear the hearing aid or glasses.
5. Watch your metabolism: diabetes, weight and LDL – raise them at your health check-up.
6. People and head: stay socially involved, get depression treated, wear a cycling helmet.
7. Save your money on ginkgo, vitamin pills without a deficiency, or "brain boosters".

This article is general information and not individual medical advice. Decisions about tests and treatment belong in a conversation with your own physician.