There is a protein in your brain called brain-derived neurotrophic factor, or BDNF, and a growing body of research says aerobic exercise is one of the most reliable ways to raise it.
BDNF helps existing neurons survive, strengthens the connections between them, and supports the growth of new brain cells in the hippocampus, the region where memories are first formed and stored.
A 2025 narrative review titled Move to Remember, published in November in the journal Geriatrics, concluded that exercise-driven BDNF release is among the most replicated mechanisms linking physical activity to better brain aging. The authors describe exercise as a "key non-pharmacological strategy" for cognitive health in older adults.
What BDNF actually does in the brain
BDNF acts a bit like fertilizer for the brain. Higher BDNF levels have been associated with enhanced spatial and verbal memory and recognition capabilities, according to a review by researchers at Northwestern University. In animal studies, boosting BDNF promotes the proliferation, migration and maturation of new neural stem cells, particularly in the hippocampus.
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The hippocampus is one of the first regions damaged in Alzheimer's disease, and it also shrinks with normal aging. That is why the BDNF pathway is interesting to neuroscientists: it targets exactly the tissue most vulnerable to age-related memory loss.
How exercise turns the tap on
A detailed 2023 review of the molecular pathways, published in Frontiers in Molecular Neuroscience, maps three ways aerobic exercise appears to raise brain BDNF.
Firing neurons open calcium channels that switch on the BDNF gene. Increased blood flow through the brain's small vessels prompts endothelial cells lining those vessels to release BDNF of their own. And muscles working hard pump out molecules, including lactate, that cross the blood-brain barrier.
The endothelial contribution is bigger than it sounds. The review notes that cerebral endothelial cells synthesize far more BDNF than cortical neurons in culture. Lactate, once dismissed as a fatigue byproduct, appears to be an active messenger from muscle to brain.
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The dose that seems to matter
The Move to Remember review reports that "intense cardio and endurance exercise temporarily increased circulating BDNF, with sessions lasting more than 30 min inducing higher increases" than shorter ones.
Longer programs, such as 12 months of aerobic training, produced progressively larger effects on brain connectivity and cognition. Even a single session of moderate-to-vigorous activity produced measurable changes in brain network organization.
A September 2025 systematic review and meta-analysis in Frontiers in Aging Neuroscience pooled 17 studies in 900 older adults and found that walking, running and cycling significantly raised circulating BDNF (standardized mean difference 0.62). Low-intensity walking came out on top in the ranking of protocols, a reassuring finding for readers who are not runners.
Who may benefit the most
The dementia signal is harder to pin down, but consistent. According to the Move to Remember review, longitudinal studies indicate that "engaging in physical exercise at least three times a week reduces the risk of developing dementia."
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The review also cites early evidence from the Cardiovascular Health Cognition Study that carriers of APOE ε4, the strongest genetic risk factor for Alzheimer's disease, had a substantially reduced dementia risk when they were physically active compared with inactive carriers.
The evidence remains largely correlational and mechanistic rather than proof that any specific workout prevents Alzheimer's. But the direction is remarkably consistent across mouse work, human blood measurements and brain imaging.
For anyone concerned about memory changes or a family history of dementia, the practical takeaway is not a new pill. It is that a brisk walk of 30 minutes or more, done a few times a week, appears to switch on the same brain chemistry researchers are still trying to bottle. People with existing cognitive symptoms should raise them with a doctor rather than self-manage.
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This article is made and published by Jesper Bengtson, who may have used AI in the preparation.