Brain health: what protects the brain, and what the newest evidence adds

What "brain health" means

Brain health is the ability to remember, reason, plan, pay attention and regulate mood across a lifetime. Alzheimer's disease is the most common cause of its loss in later life, but the brain is also damaged by small strokes, by chronic high blood pressure, by untreated hearing and vision loss, by depression and by long periods of inactivity or isolation. The practical consequence is that most of what protects the brain is the same list that protects the heart.

The fourteen modifiable risk factors

The 2024 report of the Lancet standing Commission on dementia identified fourteen risk factors that, taken together, account for roughly 45 percent of dementia cases. Two were added in 2024: untreated vision loss and high LDL cholesterol.

The Commission's estimate is a population figure. For an individual it means that the odds can be shifted, not that any one person can be guaranteed protection.

What the trials show

US POINTER (2025)

The largest US lifestyle trial, published in Journal of the American Medical Association in August 2025, randomised more than 2,000 older adults at risk of cognitive decline to either a structured programme (supervised exercise, the MIND diet, cognitive training, social activity and health monitoring) or a self-guided version. Both groups improved on global cognition over two years, and the structured group improved more. The difference was modest and the trial could not say which component mattered most, but it confirmed that a multidomain programme is safe and feasible at scale.

Hearing: the ACHIEVE trial (2023)

Hearing aids did not slow cognitive decline across the whole trial population, but in the subgroup of older adults at higher risk of decline they slowed it by about half over three years. Treating hearing loss is one of the few interventions with a randomised trial behind it.

Blood pressure: SPRINT MIND (2019)

Intensive blood pressure control (target below 120 mmHg systolic) reduced the risk of mild cognitive impairment compared with the standard target of 140 mmHg. The trial ended early and was underpowered for dementia itself, but the direction was consistent. See the heart health page for the detail.

Sleep, mood and connection

• Sleep. Deep sleep is when the brain clears waste products including amyloid. Untreated sleep apnoea, chronic short sleep and long-term use of sedating sleep medicines all carry higher dementia risk in observational studies. A US trial of the sleep drug suvorexant for prevention is under way (see the trials page).
• Mood. Depression is both a risk factor and an early symptom. Treating it is worthwhile in its own right.
• Connection. Social isolation in later life is one of the fourteen factors. Structured group activity, volunteering and learning are the practical responses.

Early detection is changing fast

Blood tests that measure phosphorylated tau (p-tau217) can now identify Alzheimer's brain changes with accuracy close to spinal fluid tests. A September 2026 study in Journal of the American Medical Association showed that p-tau217 levels in cognitively normal adults predicted who would progress to cognitive impairment, and an October 2026 randomised trial in JAMA Neurology found that disclosing blood-biomarker results earlier improved diagnostic certainty and changed clinical management. These tests are ordered by clinicians, not sold to consumers, and they measure the disease process directly, which is why they now outperform any genetic score. The research page lists the papers.

What AI adds

Machine learning helps clinicians read scans and combine blood, genetic and cognitive data; it also drives the speech and digital tests under study for very early detection. None of this replaces the basics above. The strongest, best-replicated evidence for protecting the brain still concerns blood pressure, hearing, activity, diet and social contact.