Want to Enlarge Your Brain? Get Fit!

The hippocampus (which derives its name from the Greek for “seahorse”) is the part of the brain that’s important for its role in short-term memory and spatial navigation. In Alzheimer's, the hippocampus is one of the first regions to suffer damage, and memory problems and disorientation appear among the first symptoms. Elderly people tend to have smaller hippocampi (there’s one on each side), without this being closely associated with dementia. The volume of the hippocampi can be measured using magnetic resonance imaging (MRI). In people who don’t have Alzheimer's, the volume of the hippocampus decreases by about 4% over 2 years; but in people with early Alzheimer's, the volume decreases by 10% over the same time.

An article in the journal Hippocampus describes the relationship between the size of hippocampus in elderly people, their spatial reasoning, and their levels of fitness. (Here’s a link to one spatial reasoning test.) The population studied comprised 165 men and women aged between 59 and 81.

Higher fitness levels were associated with larger left and right hippocampi after adjustments were made for age, sex, and years of education. Larger hippocampi and higher fitness levels were both linked with better spatial memory performance. Statistical analyses were able to show that hippocampal volume was partially responsible for the relationship between higher fitness and improved spatial memory.

The results of this study show that higher levels of aerobic fitness are associated with increased hippocampal volume in older humans, which translates to better memory function. The obvious answer for us as we get older is to keep up our levels of aerobic exercise, hoping that our hippocampi will stay large and fully functional.