A recent study from Johns Hopkins University has uncovered what might be the most accessible brain-protection strategy yet: just 35 minutes of moderate-to-vigorous physical activity per week—that’s a mere 5 minutes daily—could slash your dementia risk by a remarkable 41 percent compared to those who remain sedentary.
You read that correctly. It’s not 35 minutes daily, not even 35 minutes three times weekly, but just 35 minutes total across your entire week.
For perspective, that’s less time than most people spend scrolling social media during a single bathroom break.
The extensive research tracked nearly 90,000 adults (with a median age of 63) over 4.4 years using wrist-worn activity monitors to precisely measure movement patterns.
This approach replaced the notoriously unreliable self-reporting methods that have limited previous studies.
“Our findings suggest that increasing physical activity, even as little as five minutes per day, can reduce dementia risk in older adults,” explains Johns Hopkins epidemiologist Amal Wanigatunga, who led the research team.
You’re Probably Overestimating How Much Exercise You Need
For decades, public health messaging around exercise has emphasized meeting ambitious targets—10,000 steps daily, 150 minutes of weekly moderate activity, or intense gym sessions several times per week.
These recommendations, while scientifically sound for optimal health, have inadvertently created a psychological barrier for many people.
Here’s what most exercise advocates won’t tell you: the steepest benefits curve occurs at the very beginning of the activity spectrum.
In other words, the difference between zero exercise and a tiny amount is actually more significant than the difference between moderate and high amounts of physical activity when it comes to brain protection.
The Johns Hopkins study demonstrates this principle clearly.
While those logging more than 140 minutes of weekly exercise showed the greatest risk reduction (69 percent lower dementia risk), even the modest 36-70 minute weekly group saw a dramatic 60 percent reduction compared to non-exercisers.
This counterintuitive finding challenges the “more is better” assumption that dominates fitness discourse.
For brain health specifically, merely breaking the inactivity cycle appears to trigger significant protective mechanisms.
Age and Frailty Are No Barriers to Benefit
Perhaps the most encouraging aspect of the new research is that the protective association between physical activity and reduced dementia risk remained consistent regardless of participants’ age or physical condition.
“This suggests that even frail or nearly frail older adults might be able to reduce their dementia risk through low-dose exercise,” Wanigatunga notes.
This finding dismantles another common misconception—that preventative measures only benefit those who start early.
The data shows that introducing even minimal physical activity can provide substantial neurological protection at any life stage, including for those already experiencing physical limitations.
For adults concerned about cognitive decline who have been sedentary for years or decades, this represents a powerful opportunity.
Previous research has shown that beginning an exercise routine can help reverse the effects of long-term inactivity, suggesting it’s genuinely never too late to start.
The Dose-Response Relationship
The Johns Hopkins team identified a clear dose-response pattern between physical activity and dementia protection:
- 0 minutes weekly: Baseline risk (control group)
- 1-35 minutes weekly: 41% lower risk
- 36-70 minutes weekly: 60% lower risk
- 71-140 minutes weekly: 63% lower risk
- 140+ minutes weekly: 69% lower risk
This graduated response suggests that while any movement provides substantial benefits, additional activity continues to enhance protection—albeit with diminishing returns after the initial dramatic improvement.
Dr. Wanigatunga emphasizes that these findings should reshape how we think about exercise promotion: “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.”
How Exercise Physically Protects Your Brain
While the study establishes a strong statistical association between physical activity and reduced dementia risk, it doesn’t definitively prove causation.
However, multiple biological mechanisms likely explain this relationship:
- Enhanced cerebral blood flow — Physical activity increases circulation throughout the body, including to the brain, delivering vital oxygen and nutrients while removing waste products.
- Neuroplasticity stimulation — Exercise triggers the release of brain-derived neurotrophic factor (BDNF), a protein that promotes the growth and maintenance of neurons.
- Inflammation reduction — Regular physical activity helps control chronic inflammation, which has been implicated in neurodegeneration.
- Hippocampal growth — Previous research has shown that exercise can actually increase the size of the hippocampus, a brain region crucial for learning and memory that typically shrinks with age.
- Improved glucose metabolism — Physical activity enhances insulin sensitivity and glucose utilization, potentially protecting against the metabolic dysregulation that may contribute to Alzheimer’s disease.
These mechanisms working in concert likely explain why even modest amounts of movement can yield significant cognitive protection.
Making Your 35 Minutes Count
If you’re motivated by this research to incorporate more movement into your routine, consider these practical approaches:
- Break it down: Just 5 minutes daily achieves the minimum protective threshold.
- Focus on intensity: The study measured moderate-to-vigorous physical activity, suggesting that brief intervals of higher-intensity movement might be particularly beneficial.
- Choose sustainable activities: Walking, swimming, gardening, or dancing can all contribute to your weekly total.
- Track accurately: Consider using a fitness tracker to objectively measure your activity rather than relying on subjective impressions.
- Start where you are: For those currently inactive, even standing up and moving around the house more frequently can begin building the exercise habit.
The key insight is removing the perception that worthwhile exercise must be lengthy, structured, or uncomfortable.
For brain protection specifically, the evidence suggests that simply avoiding complete sedentarism provides substantial benefits.
A Multi-Faceted Approach to Brain Health
While this study highlights the outsized impact of even minimal physical activity, experts still recommend a comprehensive approach to cognitive protection that includes:
- Mediterranean-style diet rich in vegetables, fruits, whole grains, fish, and olive oil
- Quality sleep of 7-8 hours nightly
- Cognitive engagement through learning new skills and social interaction
- Stress management through mindfulness practices or other relaxation techniques
- Blood pressure control through medication if necessary
The exciting aspect of the new findings is how they democratize brain health by making at least one powerful protective factor accessible to virtually everyone, regardless of time constraints, financial resources, or physical limitations.
Research Implications and Future Directions
This study represents a significant advancement in our understanding of the physical activity-dementia relationship thanks to its large sample size, objective measurement techniques, and focus on practical, achievable activity levels.
Future research will likely explore:
- Optimal timing of physical activity across the lifespan
- Whether specific types of exercise provide enhanced protection
- How activity interacts with genetic risk factors for dementia
- Potential differences in effect between various dementia subtypes
- Mechanistic studies to further clarify the biological pathways involved
For now, the practical takeaway is clear: movement matters for brain health, and the barrier to entry is remarkably low.
As Dr. Wanigatunga concludes: “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.”
In a world where dementia cases are projected to triple by 2050, this accessible intervention offers hope that meaningful prevention might be within reach for millions of people—starting with just five minutes a day.
The research discussed in this article was published in the Journal of the American Medical Directors Association in March 2025.
