Researchers discovered that just 40 minutes of moderate exercise in pensioners physically grows the brain and helps people boost their brain power. The regular workout works on people already showing signs of dementia and loss of brain function. Most elderly people experience some difficulty in remembering as an area of the brain associated with memory known as a the hippocampus shrinks as we get older. Around 820,000 in Britain suffer more serious dementia. But the new study suggest this can be warded off and even reversed with regular exercise.