Every now and then, some research comes up that makes good sense. Two recent studies, from the US and the Netherlands, suggest that simply taking a good walk keeps your brain in shape and helps ward off Alzheimer's disease.
The studies, published in the Journal of the American Medical Association last month, examined exercise levels among the elderly, and then looked at whether this had any effect on their mental functioning and general health. One study, of 2,257 men in Hawaii aged between 71 and 93, looked at how much walking each man did each day. Those who walked less than 400 metres each day were twice as likely to develop a form of brain deterioration such as Alzheimer's than those who walked more than 3km.
The average human walking speed is about 6km per hour, so 3km shouldn't amount to much more than 30 minutes of brisk walking. Of course, if you're a little on the slow side, you might have to walk for an hour to get your daily brain exercise.
If you think there's no way you can squeeze an hour's walking into your busy daily schedule, another study has found that even 30 minutes every other day is better than nothing. This research, part of a long-term study of female nurses, found that, of those studied aged 70 to 81, even those who managed to walk for only 90 minutes a week performed better in brain-assessment tests than women who were inactive.
Why is walking good for your brain? There are some obvious benefits: it gets the blood flowing, which, in turn, increases oxygen flow and helps clear the toxins clogging your circuits.
In Alzheimer's disease, a substance called amyloid starts building up in the brain and twisting the nerve fibres so they end up looking like the inside of my mother's knitting bag. Other forms of brain deterioration - the dementias - are caused by the blood vessels getting clogged by fats, cholesterol and debris.
