It's enough to walk for 50 minutes a day, three days a week to reduce your chances of mental decline, researchers have found.
They tested the theory on a group of 170 individuals aged 50 or older, who were in reasonable health. Half were assigned to minimal activity over a 24-week period, and the rest had to perform some physical activity that lasted for at least 50 minutes, and which they did three times a week. Most in the activity group decided to walk for 50 minutes, although some included light strength-training exercises.
During the six months, those in the activity group improved their score on a cognitive test by 1.3 points compared with those who were inactive; by comparison, people taking the anti-Alzheimer's drug Aricept (donepezil) see an improvement of just 0.5 points when they use the same test.
The benefits continued for 18 months afterwards.
(Source: Journal of the American Medical Association, 2008; 300: 1027-37).