New York: Taking regular walks can help prevent Alzheimer’s Disease in older people, new research from the National Institute of Aging in Maryland has found.

Those who exercise three times a week during old age are a third less likely to develop dementia than the less active, research shows.

Walkers and cyclists are at lower risk of the disease, a study of more than 1,700 pensioners found. Aerobics and weight training are also beneficial.

The US research followed the progress of volunteers for six years. All were over 65 and in good health.

At the end of the study there were more cases of dementia, including Alzheimer’s, in those who took little or no exercise.

Those who exercised at least three times a week for at least 15 minutes at a time were 32 per cent less likely to develop the condition.

Researcher Dr Eric Larson, from the National Institute of Ageing in Maryland, said: ‘Even those elderly people who did modest amounts of gentle exercise, such as walking for 15 minutes three times a week, appeared to benefit. Even if you’re 75 and have never exercised before, you can still benefit by starting to exercise now.’

Alzheimer’s is the most common cause of dementia with more cases being diagnosed each year. For some, drugs can delay the progress of symptoms such as memory loss and the erosion of ability to do everyday tasks, but there is no cure.

However, exercising boosts blood flow to the parts of the brain used for memory, Dr Larson said.

‘Earlier research has shown that poor blood flow can damage these parts of the brain,’ he said. ‘So one theory is that exercise may prevent damage and might even help repair these areas by increasing blood flow.’

Writing in the journal Annals of Internal Medicine, the researchers said the social aspect of exercising may help keep men and women alert.

Previous findings have shown that exercise may keep Alzheimer’s at bay by reducing levels of amyloid, a sticky protein that clogs the brains of those with the disease, leading to nerve damage and memory loss.

Regular activity also helps prevent diabetes and high blood pressure – both of which increase the risk of Alzheimer’s.

It is also possible those who exercise regularly as pensioners will have led healthier lifestyles over the years.

Researchers will investigate whether some types of exercise are better than others at warding off dementia.