Small amounts of movement every day may lower your risk for dementia. (© NDABCREATIVITY – stock.adobe.com)
In a nutshell
- Even minimal physical activity (as little as 5 minutes daily or 35 minutes weekly) was associated with a 41% reduced risk of dementia compared to no activity at all.
- The protective effects of exercise against dementia remained consistent regardless of frailty status, suggesting physical activity benefits brain health even for frail older adults.
- While current guidelines recommend 150 minutes of weekly exercise, this study suggests that starting with much smaller, achievable activity goals could still provide significant brain health benefits.
BALTIMORE — For older adults concerned about cognitive decline, new evidence suggests that the journey to better brain health might begin with remarkably small steps. A mere 5 minutes of daily physical activity could be enough to help ward off dementia, according to new research from Johns Hopkins University.
In fact, researchers say that as little as 35 minutes of moderate exercise per week was associated with a 41% reduction in dementia risk, upending conventional wisdom about minimum effective exercise “doses.” While public health guidelines typically recommend 150 minutes of moderate activity per week, the study, published in the Journal of Post-Acute and Long-Term Care Medicine, aligns with a growing body of evidence supporting a “some is better than none” approach to physical activity.
Dementia, a condition marked by cognitive decline severe enough to interfere with daily life, remains one of our most feared health conditions, and for good reason. As a leading cause of death without a cure, dementia affects millions worldwide, with cases expected to triple by 2050 as the global population ages. In the United States alone, dementia affects approximately seven million people, including about a third of those aged 85 years or older. The condition takes a devastating toll on patients and caregivers alike, making prevention strategies increasingly important.
For many older adults, particularly those dealing with frailty or health limitations, meeting the standard exercise guidelines can seem like an insurmountable challenge. This research offers a more accessible path to brain health protection that might be achievable for most people, regardless of their current physical condition.
How moderate exercise fights dementia
“Our findings suggest that increasing physical activity, even as little as five minutes per day, can reduce dementia risk in older adults,” says study lead author Amal Wanigatunga, Ph.D., assistant professor in the Bloomberg School’s Department of Epidemiology, in a statement. “This adds to a growing body of evidence that some exercise is better than nothing, especially with regard to an aging-related disorder that affects the brain that currently has no cure.”
The study, led by Wanigatunga and colleagues from Hopkins, analyzed data from nearly 90,000 adults in the UK Biobank project who wore wrist accelerometers to objectively measure their physical activity levels. This approach overcame a significant limitation of previous research, which often relied on self-reported activity that can be unreliable, especially in older populations who might have memory issues.
Participants had a median age of 63, with women making up 56% of the sample. Over an average follow-up period of 4.4 years, 735 people developed dementia. Researchers found that for every additional 30 minutes of weekly moderate-to-vigorous physical activity (MVPA), there was a 4% reduction in dementia risk. But the most striking finding came when comparing people who got no physical activity at all to those who managed even minimal amounts.
Those who engaged in just 1-35 minutes of MVPA per week showed a remarkable 41% reduced risk of dementia compared to completely inactive individuals. The risk reduction increased to 60% for those doing 36-70 minutes weekly, 63% for 71-140 minutes, and 69% for those exceeding 140 minutes. These results suggest that the greatest benefit per minute of exercise comes from moving from no activity to even a small amount.
Many seniors may shy away from exercise because of their frailty. Luckily, the study found that the dementia-protective effects of exercise held true regardless of frailty status. While frailty itself increased dementia risk, prefrail individuals had a 47% higher risk and frail individuals had double the risk compared to robust participants, physical activity remained protective across all groups.
Get moving
What constitutes moderate-to-vigorous physical activity? The researchers defined it as movement equivalent to activities like brisk walking, gardening, dancing, cycling, or swimming. Essentially, MVPA consists of doing anything that gets your heart rate up and makes you breathe a bit harder while still being able to talk. For frail older adults, this might include activities as simple as walking to the mailbox, doing light housework, or performing gentle strength exercises while seated.
Physical activity improves blood flow to the brain, reduces inflammation, stimulates the growth of new brain cells, and strengthens connections between neurons. Exercise also helps control risk factors for dementia, including high blood pressure, diabetes, and obesity. Some researchers believe regular activity might even directly reduce the buildup of harmful proteins in the brain that are associated with Alzheimer’s disease.
Studies in recent years have suggested that dementia is somewhat preventable within a normal lifespan through lifestyle changes that include better control of cholesterol, blood pressure, and blood sugar, and being more physically active. However, the minimum amount of activity needed to reduce dementia risk meaningfully hasn’t been clear until now.
For older adults with mobility challenges or health concerns that make exercise difficult, these findings offer hope. Small, manageable increases in physical activity could yield meaningful cognitive benefits. Taking a short walk around the block, doing chair exercises while watching television, or even gardening for a few minutes daily might make a difference.
Healthcare providers may want to consider recommending small activity goals rather than immediately pushing for the full 150 minutes per week recommended in guidelines. Starting with achievable targets could help build confidence and gradually increase activity levels without overwhelming patients who are currently inactive.
The body responds dramatically to initial increases in activity after being sedentary, with diminishing returns as activity levels increase further. Even small amounts of movement represent a significant percentage increase in physical demands for someone doing no activity at all, triggering beneficial adaptations.
For family members and caregivers of older adults, simple strategies to increase daily movement might include short walks, gentle movement classes, or incorporating more movement into daily routines. Consider parking farther from store entrances or taking stairs instead of elevators when possible.
Wanigatunga and his colleagues recommend that future clinical trial-type studies investigate low-dose exercise as an important initial step toward increasing physical activity as a dementia-preventing strategy. As the global population ages and dementia rates rise, finding accessible prevention strategies becomes increasingly crucial. Exercise represents one of the most promising approaches, particularly because it addresses multiple risk factors simultaneously and generally has positive effects on overall health and quality of life.
If you find fitness messaging intimidating, you are not alone. This research offers a glimmer of hope for those who have avoided exercise due to health concerns or are afraid to tackle exercise outside of their comfort zone. When it comes to brain health, every move counts and even small steps can take you in the right direction.
Paper Summary
Methodology
The research team conducted a survival analysis within a prospective cohort study using data from the UK Biobank project. They included 89,667 participants (median age 63, 56% women) who wore Axivity AX3 triaxial wrist-worn accelerometers between February 2013 and December 2015. Participants wore these devices continuously for up to seven days, with researchers analyzing only those who had valid wear data for at least three days with 95% daily wear time (1,368 minutes per day).
The team excluded participants who already had dementia before wearing the accelerometer, those with stroke or Parkinson’s disease, and those with missing sociodemographic information or physical activity measures.
The researchers estimated MVPA from the accelerometer data using a threshold of >193 milli-g, calculated as a modified version of the Euclidean norm minus one and averaged at 5-second intervals. They then summarized this into minute-level data, identified minutes meeting the MVPA threshold, and multiplied average daily MVPA by 7 to establish weekly averages.
Frailty status was assessed using a modified version of the physical frailty phenotype based on five criteria: low hand-grip strength, slow walking speed, unintentional weight loss, self-reported exhaustion, and low self-reported physical activity. Participants with 0 criteria were labeled robust, 1-2 criteria as prefrail, and ≥3 criteria as frail. The primary outcome, time to first incident all-cause dementia, was identified using multiple ICD-10 codes from linked hospital inpatient data through November 8, 2021.
Results
Over an average follow-up period of 4.4 years, 735 participants (0.08% of the sample) developed dementia. The average weekly MVPA across all participants was 89.8 minutes, though this varied widely.
The study found that for every additional 30 minutes of weekly MVPA, there was a 4% reduction in dementia risk after adjusting for age, sex, BMI, frailty, and number of existing medical conditions. When compared to participants with zero minutes of weekly MVPA, those engaging in 1-35 minutes had a 41% lower risk (HR 0.59), those with 36-70 minutes had a 60% lower risk (HR 0.40), those with 71-140 minutes had a 63% lower risk (HR 0.37), and those exceeding 140 minutes had a 69% lower risk (HR 0.31).
All of these reductions were statistically significant. Approximately 59% of participants were categorized as robust, 38.6% as prefrail, and 2.2% as frail. While prefrailty was associated with a 47% higher dementia risk and frailty with a 101% higher risk compared to robust participants, the protective effect of MVPA remained consistent across all frailty categories, with no significant interaction between activity levels and frailty status (interaction p-values all >0.21).
These results remained robust in multiple sensitivity analyses, including adjusting for time between frailty measurement and accelerometry, restricting analyses to different age groups, removing early dementia cases, and accounting for death as a competing risk.
Limitations
The researchers acknowledged several limitations.
- The UK Biobank is not fully representative of the United Kingdom population, though it provides a large sample with extensive health measurements.
- Unmeasured or residual confounding factors might exist despite adjusting for numerous potential confounders.
- The study used a modified version of the physical frailty phenotype rather than the standard definition.
- Frailty was measured an average of 4 years before accelerometry collection, potentially underestimating frailty prevalence at the time of activity measurement.
- The possibility of reverse causation exists—early, undiagnosed dementia might have reduced activity levels rather than low activity causing dementia—though sensitivity analyses removing cases occurring in the first two years produced similar results.
- Accelerometry cannot capture the specific type of activity performed, potentially misclassifying some activities and underestimating the true relationship between MVPA and dementia risk.
Takeaways and Discussion
The study’s findings suggest that any amount of MVPA, even as little as 1-35 minutes per week (approximately 5 minutes daily), is associated with a significantly reduced risk of dementia compared to no activity. This risk reduction increases with higher activity levels, but the greatest benefit per minute appears to come from moving from complete inactivity to even minimal activity.
These protective effects persist regardless of frailty status, suggesting that physical activity remains beneficial even for those with physical limitations. The researchers propose that promoting any MVPA engagement for decreasing dementia risk is particularly effective for those currently inactive—levels common among frail older adults. These findings support previous research showing inverse dose-response relationships between physical activity and dementia risk, but extend this work by using objectively measured activity data and specifically examining the effects at low activity levels.
The results suggest that waiting until one can achieve recommended activity levels (150 minutes weekly) might mean missing substantial benefits available from more modest activity levels. For frail older adults, who often find standard exercise guidelines daunting, these findings offer hope that even small increases in physical activity might yield meaningful cognitive benefits.
Funding and Disclosures
Dr. Wanigatunga was supported by the National Institute on Aging, National Institutes of Health (grant number K01 AG076967). Dr. Wanigatunga, Dr. Crainiceanu, and Dr. Schrack were supported by the National Institute on Aging, National Institutes of Health (grant number R01 AG075883). The researchers disclosed that Dr. Schrack serves as a consultant for Edwards Lifescience and on the board of BellSant, Inc. Dr. Crainiceanu consults with Bayer and Johnson and Johnson on methods development for wearable devices in clinical trials, though these relationships had no direct or apparent relationship with this manuscript. The remaining authors declared no conflicts of interest.
Publication Information
This study, titled “Moderate-to-Vigorous Physical Activity at any Dose Reduces All-Cause Dementia Risk Regardless of Frailty Status,” was published in the Journal of Post-Acute and Long-Term Care Medicine (JAMDA), (Volume 26, 2025, article 105456) on January 15. The lead author was Amal A. Wanigatunga, Ph.D., from the Department of Epidemiology at Johns Hopkins Bloomberg School of Public Health, who is also a core faculty member at the Johns Hopkins Center on Aging and Health with a joint appointment at the Johns Hopkins University School of Medicine. Co-authors included Yiwen Dong, Mu Jin, Andrew Leroux, Erjia Cui, Xinkai Zhou, Angela Zhao, Jennifer Schrack, Karen Bandeen-Roche, Jeremy Walston, Qian-Li Xue, Martin Lindquist, and Ciprian Crainiceanu.
