Medicine
The Influence of Physical Exercise on Neurocognitive Aging
Quick fact
One session of moderate aerobic exercise can increase brain-derived neurotrophic factor (BDNF) levels in the blood for up to an hour, and regular exercise can lead to a measurable increase in hippocampus volume by 1–2% over a year.
Why this is interesting
You know exercise keeps your muscles strong—but did you know it can actually remodel your brain, making your memory sharper and your thinking faster even as you age?
Read the full explanation
Understanding The Influence of Physical Exercise on Neurocognitive Aging
Think of your brain as a garden. As you age, the soil (brain tissue) naturally becomes less fertile: cells shrink, connections thin, and the growth of new neurons slows. Physical exercise acts like a gardener adding rich compost—it revitalises the soil by releasing chemicals that encourage new growth. When you jog, cycle, or swim, your muscles release substances that travel to the brain. The most important is BDNF (brain-derived neurotrophic factor), a protein that acts like fertilizer for neurons. It stimulates the growth of new neurons (neurogenesis), strengthens connections between them (synaptic plasticity), and encourages the formation of new blood vessels (angiogenesis) to feed the growing network. This is especially noticeable in the hippocampus, the brain's key memory centre. The result: you maintain and even improve memory, attention, and the ability to plan and multitask—the 'executive functions' that often decline with age.
A deeper explanation
The mechanism behind exercise's cognitive benefits is a complex cascade. Muscle contractions during exercise release molecules like irisin and myokines, which cross the blood-brain barrier and activate intracellular pathways that increase BDNF production. BDNF binds to TrkB receptors on neurons, triggering signaling cascades (e.g., MAPK, PI3K/Akt) that enhance synaptic plasticity and neuronal survival. Additionally, exercise promotes the release of serotonin, dopamine, and norepinephrine, which improve mood and attention. In the hippocampus, exercise specifically stimulates neurogenesis in the dentate gyrus, a region critical for pattern separation and memory. Animal studies show that running increases the number of new neurons; human studies show that a year of aerobic exercise increases hippocampal volume by ~2%, effectively reversing age-related shrinkage. Furthermore, exercise reduces chronic inflammation and oxidative stress, two key drivers of aging, by improving mitochondrial function and cellular repair processes. It also increases cerebral blood flow, delivering oxygen and nutrients. These changes—neurogenesis, synaptogenesis, angiogenesis, and reduced inflammation—compound over time, resulting in preserved cognitive function, slower cognitive decline, and reduced risk of dementia. While most research focuses on aerobic exercise, resistance training also improves executive function and memory, likely through similar BDNF-related mechanisms and insulin-like growth factor 1 (IGF-1). Importantly, the window for benefit is broad: even starting exercise later in life yields measurable gains, and the effects are dose-dependent—more exercise, up to a point, yields greater benefit. This makes exercise a unique, cost-effective, and universally available intervention to maintain brain health into old age.