Neuroscience
Does aerobic exercise grow the hippocampus?
A randomised trial in 120 older adults showed that a year of aerobic exercise increased hippocampal volume and improved spatial memory. What this result establishes — and what it leaves open.
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The hippocampus, a key memory region, shrinks with age, which goes along with memory problems and higher dementia risk. Can that decline be slowed? A widely cited study tested aerobic exercise.
The trial
Erickson et al. (2011) ran a randomised controlled trial in 120 older adults.
- Aerobic training increased the volume of the anterior hippocampus by 2% — which, according to the authors, is equivalent to reversing 1 to 2 years of age-related loss.
- In the control group, hippocampal volume declined.
- Spatial memory improved.
- The volume increase was associated with higher blood levels of BDNF, a protein involved in brain plasticity and neurogenesis in the dentate gyrus.
- The caudate nucleus and thalamus did not change: the effect was not global.
Caution
- It is one trial, in older people: it does not show the same effect in young adults.
- The link with BDNF is a correlation: it does not establish that BDNF produces the volume gain.
- The volume of a structure is not the same as its function. The memory improvements are real, but modest and need confirming in other cohorts.
- Whether new neurons form in adulthood is itself debated (see our “Neuromyths” quiz): the exact mechanism remains open.
Takeaway: it is one of the strongest arguments for making regular physical activity part of brain hygiene, without guaranteeing an effect for everyone.
Sources
According to PubMed:
- Erickson K. I. et al. (2011). Exercise training increases size of hippocampus and improves memory. PNAS. DOI