What is the hippocampus?
The hippocampus is a small, seahorse-shaped region deep in the brain that turns new experiences into lasting memories and helps you find your way around.
Think of the hippocampus as your brain's "save button" and filing clerk. It takes today's experiences, decides what's worth keeping and files it into long-term storage.
Why it matters for aging
The name comes from the Greek word for seahorse, because of its curved shape. You have two, one on each side of the brain. It's one of the few brain regions where new nerve cells may keep forming in adults, at least in animals, which is part of why it responds to exercise.
It's also one of the first regions affected in Alzheimer's disease, which is why so much research focuses on keeping it healthy. Aerobic exercise, good sleep and BDNF, a growth protein that acts like brain fertilizer, all appear to support it.
A common myth
Once your brain starts shrinking with age, there's nothing you can do about it.
The hippocampus typically shrinks slowly with age, but it responds to how you live. In a year-long trial in older adults, regular walking increased its size by about 2 percent, while it shrank in a stretching-only group.
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Updated Nov 9, 2026 · All terms