The strongest evidence-based strategies to protect cognitive health are: regular aerobic exercise, quality sleep, cardiovascular health, social engagement, cognitive stimulation, and managing conditions like hypertension and diabetes. Brain training apps can play a supporting role — particularly speed-of-processing training, which has the strongest evidence — but they work alongside these fundamentals, not in place of them.
Cognitive decline is one of the most feared aspects of aging, and one of the most misunderstood. The good news that often gets buried: a growing body of research links specific lifestyle habits to better brain health and lower dementia risk. The uncomfortable news: none of them are quick fixes. Here is what the evidence suggests.
First: what “cognitive decline” actually means
Some cognitive change is a normal part of aging. Processing speed slows. New name learning becomes harder. Multitasking becomes more effortful. These are normal and do not indicate disease.
Mild cognitive impairment (MCI) is a distinct step beyond normal aging — noticeable memory or thinking problems that do not yet significantly interfere with daily life. Estimates vary, but a nationally representative US study classified about 22% of adults 65 and older as having MCI. Some progress to dementia; some do not.
Dementia is a broader term for significant cognitive impairment that interferes with daily life. Alzheimer’s disease is the most common cause but not the only one.
The strategies below aim to protect against decline generally — supporting normal healthy aging and reducing risk of MCI and dementia. They are not treatments for existing dementia.
If you are worried about your own cognitive changes or a loved one’s, please talk to a doctor rather than self-diagnosing from articles. A proper evaluation is genuinely useful.
The evidence-based strategies, ranked by strength of evidence
The 2024 Lancet Commission on dementia prevention, intervention, and care identified 14 modifiable risk factors and estimated that addressing them could prevent or delay nearly half of dementia cases worldwide. These are the areas where individual action has the strongest evidence.
Regular aerobic exercise — the single strongest intervention
The evidence: aerobic exercise has some of the strongest evidence of any single intervention for cognitive health. Regular physical activity is associated with reduced risk of cognitive decline, dementia, and Alzheimer’s. Effects appear at moderate levels — you do not need to become a marathon runner.
What works: the general recommendation is 150 minutes per week of moderate aerobic activity (brisk walking, cycling, swimming) or 75 minutes of vigorous activity. Consistency matters more than intensity.
Why it works: exercise increases blood flow to the brain, promotes neuroplasticity, reduces inflammation, and supports cardiovascular health (which directly affects brain health).
Practical starting point: 30 minutes of brisk walking, 5 days per week. If you do only one thing on this list, this is the one.
Cardiovascular health
The evidence: what is good for the heart is good for the brain. Hypertension, high cholesterol, diabetes, and smoking are all significant risk factors for cognitive decline.
What works: monitor and treat blood pressure, cholesterol, and blood sugar. Do not smoke. If you drink alcohol, keep it moderate (research increasingly suggests less is better).
Why it matters: the brain uses 20% of your body’s oxygen. Vascular health directly affects brain function.
Quality sleep
The evidence: consistent sleep of 7-9 hours per night is associated with reduced dementia risk. Sleep is when the brain clears metabolic waste, including proteins associated with Alzheimer’s. Chronic sleep deprivation and disorders like untreated sleep apnea are meaningful risk factors.
What works: consistent sleep schedule, addressing sleep disorders (particularly sleep apnea), reducing evening screen time and caffeine.
Practical starting point: the same bedtime and wake time daily. See our best sleep apps roundup for tools that support this.
Social engagement
The evidence: social isolation is a significant risk factor for cognitive decline; robust social engagement protects against it. This effect is real and substantial in longitudinal studies.
What works: maintain relationships, engage in group activities, volunteer, join clubs, stay connected with family and friends. Both quality and quantity matter.
Why it works: social interaction is cognitively demanding in ways that solo activities are not — reading facial expressions, following conversation, remembering personal details all engage the brain.
Cognitive stimulation and continued learning
The evidence: lifelong learning and cognitive engagement are associated with reduced dementia risk. Education earlier in life protects against later decline; continued cognitive activity throughout life adds further protection.
What works: learn new skills (languages, instruments, hobbies), read regularly, engage with challenging material, take classes, do puzzles, play strategy games.
This is where brain training apps fit — as one form of cognitive stimulation among many, with the strongest evidence for speed-of-processing training specifically (more on this below).
Managing depression and mental health
The evidence: untreated depression is associated with increased dementia risk. Whether depression is a cause, an early symptom, or both is debated, so it is not yet clear how much treating it lowers dementia risk. Depression deserves care for its own sake either way.
What works: treating depression and anxiety with evidence-based approaches (therapy, medication when appropriate). See our best online therapy apps roundup for accessible options.
Hearing health
The evidence: untreated hearing loss is one of the largest single modifiable risk factors for dementia. The Lancet Commission estimates that hearing loss and high LDL cholesterol are each associated with about 7% of dementia cases worldwide, more than any other single factor. This may be because hearing loss reduces cognitive stimulation and increases social isolation.
What works: get hearing tested if you or others notice you asking people to repeat themselves. Use hearing aids if needed — modern ones are dramatically better than they were 15 years ago.
Traumatic brain injury (TBI) prevention
The evidence: even mild TBIs, particularly repeated ones, increase dementia risk. Wear helmets, prevent falls in older adults, avoid contact sports if you can.
Air pollution reduction
The evidence: long-term exposure to air pollution is associated with cognitive decline and dementia risk. This is a societal issue but also has personal implications.
What works: where possible, live in less polluted areas; use air purifiers at home; avoid heavy exercise near major roadways.
Nutrition
The evidence: the Mediterranean diet and MIND diet (Mediterranean-DASH Intervention for Neurodegenerative Delay) are linked to better cognitive health in observational studies, but the evidence is mixed.
What works: emphasize vegetables, fruits, whole grains, fish, olive oil, nuts, and legumes. Limit red meat, processed foods, and sugar. This is not a crash diet — it is a long-term eating pattern.
Where brain training apps fit in
Brain training is one of the more controversial areas in cognitive health, and honesty matters here.
The strongest evidence for brain training in older adults comes from the ACTIVE Trial — a large NIH-funded randomized trial of 2,832 older adults that followed participants for years. In a 10-year analysis, people assigned to speed-of-processing training had a 29% lower risk of dementia than the control group, while memory and reasoning training showed no significant effect. A 20-year follow-up using Medicare records, published in 2026, found about a 25% lower risk of a dementia diagnosis, but only for people who also did booster sessions.
These results are encouraging but not settled. Dementia was not the trial’s original outcome, and an independent 2026 reanalysis found that none of the 20-year results stayed statistically significant after correcting for multiple comparisons. The research links speed training to lower risk; it does not show that any app prevents dementia.
Other types of brain training have more limited evidence in daily-life transfer. But speed-of-processing training specifically has genuine research backing.
The app most closely tied to this research:
BrainHQ has the deepest research record in brain training and centers on processing-speed training specifically. It offers Double Decision, which BrainHQ says is an updated version of the speed training used in the ACTIVE Trial. That research is not fully independent: BrainHQ’s maker, Posit Science, markets the speed training software used in ACTIVE, and one author of the 20-year follow-up consults for and owns stock in the company. BrainHQ is more expensive at $96/year and its interface feels dated, but the scientific evidence is real.
It is a supporting tool, not a standalone answer. Any brain training app you use for cognitive health should complement the fundamentals above — exercise, sleep, social engagement, cardiovascular health — not replace them.
For the fuller picture, see our best brain training apps roundup, best brain training apps for seniors, or do brain training apps actually work. If you want an app for remembering specific things rather than for cognitive health, our roundup of the best memory training apps sorts the options by goal.
What does NOT have strong evidence
Being honest matters here. The following are commonly recommended for cognitive health but have weaker evidence than the strategies above:
Supplements marketed for brain health. Ginkgo biloba, various “brain-boosting” supplement blends, prevagen — the evidence for these is generally weak. Most studies show no meaningful benefit. The supplement industry is poorly regulated, and marketing far outpaces evidence.
Crossword puzzles specifically. Doing crosswords regularly is fine and probably beneficial as one form of cognitive stimulation. But the specific claim that crosswords prevent dementia is not well supported. Any complex cognitive activity likely helps similarly. Our brain training vs crosswords comparison looks at the two trials that tested them head to head.
Coconut oil, MCT oil, ketogenic diets for Alzheimer’s prevention. The evidence is weak or contradictory. Some studies show effects in specific contexts; broad recommendations are not supported.
Learning a specific “brain-boosting” activity. Playing an instrument, learning a language, meditation — all are probably beneficial as cognitive stimulation, but the specific claim that any one activity is uniquely protective is not well supported. Variety of cognitive engagement matters more than which specific activity.
A realistic daily protocol
Based on the evidence, here is a genuinely supported daily approach to cognitive health:
Move for 30 minutes — brisk walking is enough. The most important item on the list.
Sleep 7-9 hours consistently. Same bedtime, same wake time.
Eat mostly plants, fish, and whole grains. Not perfectly — sustainably.
Engage socially — call a friend, meet for coffee, join a group activity.
Learn something — read, take a class, practice a skill, do a brain training session on BrainHQ.
Manage your health — check blood pressure, address hearing loss, treat depression, do not smoke.
Protect your head — wear helmets, prevent falls, avoid unnecessary contact sport impacts.
Done consistently, this compounds. Done occasionally, it does not.
When to see a doctor
Talk to your primary care physician if you or a loved one notice:
- Memory problems that interfere with daily life (not just occasional forgetfulness)
- Difficulty with familiar tasks
- Getting lost in familiar places
- Trouble with words or names beyond normal aging
- Changes in judgment or decision-making
- Personality or mood changes
- Withdrawal from social activities
Early evaluation matters. Some causes of cognitive symptoms are treatable (thyroid issues, vitamin deficiencies, medication interactions, depression). For irreversible causes, early diagnosis allows for planning and, in some cases, treatments that can slow progression.
Family history matters. If you have a first-degree relative with early-onset Alzheimer’s or other dementias, discussing risk with a genetic counselor may be appropriate.
The bottom line
Cognitive decline is not fully preventable, but the Lancet Commission estimates that addressing 14 modifiable risk factors could prevent or delay nearly half of dementia cases. The strongest-evidenced strategies — regular aerobic exercise, cardiovascular health, quality sleep, social engagement, cognitive stimulation, hearing protection, and managing conditions like hypertension and depression — are linked to lower risk, though no single step guarantees protection.
Brain training apps play a supporting role — particularly BrainHQ, which offers an updated version of the speed training used in the ACTIVE Trial. The National Institute on Aging says there is not enough evidence that commercial brain training apps have the same effect as the trial’s training, so treat them as a complement to the lifestyle fundamentals, not a replacement.
Start with the highest-leverage single intervention: 30 minutes of brisk walking most days. Add sleep consistency. Add social engagement. Layer in cognitive stimulation. Do this for years, not weeks. That is what the evidence actually supports.
For related content, see our best brain training apps for seniors, how to improve memory, and do brain training apps actually work.