One of 5 physical dementia signs is a 10-second walking test — it raised risk almost 25-fold

There’s a simple test for dementia risk that takes about 10 seconds and needs no blood draw, MRI, or brain scan: watching someone walk across a room. Researchers who followed nearly 17,000 older adults for up to 7 years found that people whose walking speed and memory were both quietly declining together had a meaningfully higher risk of a later dementia diagnosis than those with no decline in either. Brain changes associated with Alzheimer’s are believed to begin building 20 to 30 years before diagnosis — meaning the body may be leaving clues in ways that have nothing to do with memory itself. (Based on the insights of Ben Azadi)

An Important Note Before We Start

None of what follows is a diagnostic tool, and none of it means you or someone you love has dementia. These are physical signs researchers have studied as early risk indicators — worth paying attention to and worth mentioning to a doctor, not conclusions to jump to on your own.

For context: research published in Nature Medicine following more than 15,000 adults estimated the lifetime risk of dementia after age 55 at 42% — notably higher than earlier estimates. At the same time, the 2024 Lancet Commission on dementia prevention estimated that around 44% of dementia cases may be attributable to 14 modifiable risk factors — meaning a meaningful share of risk may be within your influence.

Sign #1: How You Walk

Walking is a genuinely demanding cognitive task — your brain is simultaneously managing balance, spatial mapping, attention, timing, and motor planning, all without you noticing. This is why it can serve as an early indicator when brain function starts to falter.

The clearest evidence comes from the ASPREE trial, published in JAMA Network Open in 2022, which followed nearly 17,000 older adults (average age 75) in the US and Australia, tracking walking speed and memory every couple of years for up to 7 years. Compared to people with no decline in either measure, those who declined in both gait and memory had a hazard ratio of 24.9 for developing dementia — meaning nearly 25 times the risk. Those with gait decline alone or memory decline alone had smaller, though still elevated, risk increases. In practical numbers: fewer than 1 in 1,000 people per year in the no-decline group developed dementia, compared to more than 18 per 1,000 in the dual-decline group.

A second study — the Gait and Brain Study, published in JAMA Neurology in 2017, following 112 older adults with mild cognitive impairment for six years — found that walking alone didn’t reach statistical significance as a predictor, but “dual-task gait” (walking while counting backward out loud) predicted progression to dementia at nearly four times the risk. This suggests it’s not the legs that are the real signal — it’s the brain’s reduced capacity to run two demanding tasks simultaneously.

A third large analysis, pooling data on nearly 27,000 adults across 22 studies in 17 countries, examined a combination called “motoric cognitive risk”: slow gait plus a person’s own report that their memory feels off. This simple, no-equipment combination was associated with roughly double the risk of developing dementia.

What to actually do with this: Notice if you’ve started going quiet while walking and talking, or trailing off mid-sentence when a conversation gets complex — that’s the “dual-task cost” showing up in real life. Try walking while counting backward from 50, and mention any real difficulty with this at your next physical.

Sign #2: Grip Strength

The UK Biobank followed 466,788 adults (median age 56), measuring grip strength with a simple hand dynamometer, then tracked outcomes for about 9 years. People in the weakest fifth for grip strength had a 72% higher risk of developing dementia than those in the strongest fifth, and an 87% higher risk of dying from it. The weakest group reached the same level of dementia risk roughly 3 years earlier than the strongest group.

This is observational data — nobody was randomly assigned to be strong or weak — and grip strength itself doesn’t cause dementia. It functions more as a proxy, summarizing muscle mass, nerve function, nutrition, inflammation, and overall activity level in one simple measurement. What makes this useful practically is that muscle, unlike some other signs on this list, is something you can directly work on. Two accessible ways to start: farmer’s carries (carrying something heavy, like loaded grocery bags, dumbbells, or a kettlebell, while walking), and dead hangs from a pull-up bar. The sit-to-stand test — standing up from a chair five times without using your hands, timed — is another simple measure clinicians use to assess lower-body power.

Sign #3: Sense of Smell

Your olfactory system is the only sensory system that doesn’t route through the thalamus first — smell signals go directly into brain regions, including the hippocampus, that are among the earliest affected by Alzheimer’s-related changes.

A study published in the Journal of the American Geriatrics Society in 2018 gave a simple five-item scratch-and-sniff test to a nationally representative sample of 2,906 older Americans (ages 57-85) with normal cognition at baseline. Five years later, those who struggled with the smell test had more than double the odds of a dementia diagnosis, a result that held even after adjusting for their baseline cognitive scores. A separate study from Columbia researchers, using a longer 40-item smell test in over a thousand people in northern Manhattan, found lower smell scores predicted cognitive decline even in people whose memory tests hadn’t picked up any problem yet. A 2023 study in the journal Alzheimer’s & Dementia found that how quickly someone’s sense of smell was declining — not just whether it was already impaired — predicted higher odds of later cognitive impairment.

An important caveat: smell loss has many causes unrelated to dementia — infections, chronic sinus issues, allergies, smoking, head injury, certain medications, and normal aging can all play a role. What’s worth flagging to a doctor is a change that’s happening unusually quickly, rather than gradually over months or years. A simple home version: with your eyes closed, have someone hand you common scents (coffee, cinnamon, peanut butter, vanilla, orange peel) once a year as an informal baseline, not a diagnostic test.

Sign #4: Hearing

This has some of the more robust evidence on this list. A Johns Hopkins study, published in Archives of Neurology in 2011, followed 639 dementia-free adults from the Baltimore Longitudinal Study of Aging for a median of 12 years. Compared to normal hearing, moderate hearing loss was associated with roughly three times the dementia risk, and severe hearing loss with roughly five times the risk — with risk climbing steadily by about 27% for every 10 decibels of additional hearing loss.

Proposed explanations include the brain expending extra executive function resources just decoding degraded speech signals, reduced auditory stimulation affecting brain structures that depend on regular use, and hearing loss contributing to social withdrawal, itself a recognized dementia risk factor.

The most important and most nuanced piece of evidence here comes from the ACHIEVE trial, a randomized controlled trial published in The Lancet in 2023, involving 970 adults (ages 70-84) with untreated hearing loss, half given hearing aids and audiology support and half given general health education, over 3 years. Across the full study group, there was no significant overall difference in cognitive decline. However, in a pre-specified subgroup of 238 participants who were already at higher cardiovascular risk, the hearing intervention slowed cognitive decline by 48% over the 3 years. Most people wait roughly a decade between noticing hearing loss and doing something about it — getting a baseline hearing test now, rather than waiting, is a reasonable, low-cost step.

Sign #5: Acting Out Dreams

During normal REM sleep, the body is temporarily paralyzed (called REM atonia) as a safety mechanism, preventing you from physically acting out dreams. In some people, this mechanism fails, resulting in REM sleep behavior disorder — punching, kicking, shouting, or even leaping out of bed while still asleep, usually noticed first by a partner rather than the person themselves.

An international research group pooled data from 24 centers worldwide, following 1,280 people with this condition who had no other neurological symptoms at baseline. Roughly 6% per year converted to a neurodegenerative disease, and by 12 years of follow-up, about 73.5% had done so. It’s important to be precise here: this conversion is most strongly tied to Parkinson’s disease, dementia with Lewy bodies, and multiple system atrophy — not primarily classic Alzheimer’s disease. Still, if this describes someone in your household, it’s a strong enough predictive signal to be worth a conversation with a sleep specialist.

The Encouraging Part: A Real Trial Showing Lifestyle Change Works

The largest lifestyle trial of its kind in the US, called US POINTER, was published in JAMA in July 2025. It followed 2,111 adults (ages 60-79) at elevated risk of cognitive decline for 2 years. Everyone received a lifestyle program — half got a structured version (supervised exercise, the MIND diet, cognitive training, regular health monitoring, and team-based accountability), while half got a self-guided version with general encouragement. Both groups improved, but the structured group improved significantly more, with researchers estimating the effect was equivalent to roughly 1 to 2 years of slowed cognitive aging.

Six Practical Steps

1. Train for strength, not just cardio. Grip and lower-body power show up repeatedly in this research. Aim for 2-3 strength training sessions of 20-30 minutes weekly.
2. Get your hearing tested — this is described as the single most actionable item on this list, and one of the most commonly overlooked.
3. Manage your metabolic health — blood pressure, LDL cholesterol, blood sugar, and visceral fat are all on the Lancet Commission’s list of modifiable risk factors.
4. Take sleep seriously — deep sleep is when the brain’s glymphatic system clears metabolic waste. Avoid food within 3 hours of bed, keep the bedroom cool (roughly 65-68°F), and consider a sleep mask.
5. Stay socially engaged — isolation is a recognized, often underestimated risk factor.
6. Build a baseline and re-check it yearly — time yourself on 5 sit-to-stands, do the smell test, get your hearing checked, and track these numbers over time, since you can’t measure change on something you’ve never measured.

Frequently Asked Questions

Disclaimer: This article is for general informational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. None of the signs discussed here diagnose dementia on their own. If you notice concerning changes in walking, grip strength, smell, hearing, or sleep behavior, discuss them with your doctor for proper evaluation.