A new study shows that even 80-year-olds can grow new neurons in the hippocampus region of the brain, but this process is decreased in people with Alzheimer’s disease.

The process of growing new neurons is called neurogenesis and it is highly active during brain development but whether it occurs in adults has been unclear. An animal study published last year had shed some doubt on adult neurogenesis claiming it does not occur.

A new study using cutting-edge techniques looked at human samples and provided pretty solid evidence of neurogenesis in adult humans. It also found that in tissue samples from people with Alzheimer’s disease, neurogenesis was dramatically diminished. This is in line with brain imaging studies showing brain atrophy in the hippocampus brain region in Alzheimer’s disease patients.

One of the major regulators of neurogenesis is the growth factor BDNF. Studies have shown 30 minutes of exercise can increase BDNF in humans. BDNF is able to cross the blood-brain barrier and promote the growth of new neurons.