A new study led by Australian researchers looked at the effects of aerobic exercise on a region of the brain called the hippocampus, which is critical for memory and other brain functions. The researchers find that aerobic exercise can improve memory and maintain brain health as we age.

Brain health decreases with age, with the average brain shrinking by approximately 5% per decade after the age of 40. Studies in mice and rats have consistently shown that physical exercise increases the size of the hippocampus but until now evidence in humans has been inconsistent.

The researchers reviewed 14 clinical trials, which examined the brain scans of 737 people before and after aerobic exercise programs or in control conditions. The participants included a mix of healthy adults, people with mild cognitive impairment (such as Alzheimer’s), and people with a clinical diagnosis of mental illness including depression and schizophrenia.

Ages ranged from 24 to 76 years with an average age of 66. The effects of aerobic exercise, including stationary cycling, walking, and treadmill running were examined. The length of the interventions ranged from three to 24 months with a range of two to five sessions per week.

The results of this study showed that the left region of the hippocampus had a significantly larger size in humans that exercised. Physical exercise had no effect on total hippocampal volume. The research data showed that rather than actually increasing the size of the hippocampus, aerobic exercise slowed down deterioration in brain size.

One reason for the results of this study is that when you exercise you produce a chemical called brain-derived neurotrophic factor (BDNF), which may help to prevent age-related decline by reducing the deterioration of the brain.

The study results seem to suggest that exercise may be used for the prevention of age-related neurodegenerative disorders such as Alzheimer’s and dementia. More research is needed to ensure that this is the case. However, physical exercise is the one method that has the most evidence showing it helps to maintain brain size and function into older age