What is BDNF?
Brain-derived neurotrophic factor
BDNF is a protein your brain makes that helps nerve cells survive, grow and build new connections, which is the physical basis of learning and memory.
Think of BDNF as fertilizer for your brain. Nerve cells are the plants and their connections are the roots. With enough fertilizer, roots spread and new shoots appear. Without it, the garden slowly thins out.
Why it matters for aging
BDNF is especially active in the hippocampus, the brain region that turns experiences into memories and one of the first areas to shrink with age. Lower BDNF levels have been linked to memory decline and low mood, though scientists are still working out what is cause and what is effect.
The most striking finding comes from exercise. In a well-known trial in older adults, a year of brisk walking slightly increased the size of the hippocampus instead of letting it shrink, and those gains tracked with higher BDNF in the blood. In other words, moving your body sends a growth signal to your brain.
A common myth
You can boost BDNF by taking a BDNF supplement.
BDNF is a protein. Swallowed, it would simply be digested like any other protein, and it doesn't easily cross into the brain. What reliably raises it is what you do: aerobic exercise is the best-studied trigger, and sleep and learning new skills matter too.
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Updated Nov 7, 2026 · All terms