Regular exercise may keep Alzheimer's at bay - even in those whose genes put them in the dementia danger zone.
© AlamyA study of men and women in their 60s, 70s and 80s found that being active at least three times a week stopped the brain from shrinking potentially helping keep Alzheimer's at bay (posed by model)
A study of men and women in their 60s, 70s and 80s found that being active at least three times a week stopped the brain from shrinking.

Strikingly, even those with a common gene called APOE-e4 were protected by brisk walking, jogging, swimming and cycling. Strenuous household chores also helped.

The brain normally shrinks with age, and the hippocampus, the brain's memory hub is particularly vulnerable in those at genetic risk of dementia.

Kirk Erickson, an expert in the ageing brain, said: 'This is the first study look at how physical activity might impact the loss of hippocampal volume in people at genetic risk for Alzheimer's disease.

'There are no other treatments shown to preserve hippocampal volume in those that may develop Alzheimer's disease.

'This study has tremendous implications for how we might intervene, prior to the development of any dementia symptoms, in older adults who are at increased genetic risk for Alzheimer's disease.

The APOE-e4 gene is carried by up to 30 per cent of the population. It increases the risk of Alzheimer's in old age but not everyone with the suspect DNA will develop the disease.

The latest finding suggests the exercise may be one of the factors that decides if a brain is able to overcome its genetic inheritance.

The US researchers measured the brain size of four groups of pensioners at the start and end of the 18-month study.

The amount of exercise they did was monitored and they were tested for the APOE-e4 gene.

The only brain shrinkage occurred in those with the gene who did little or no exercise.

Those with the gene who were at least moderately physically active three times a week or more were protected, the journal Frontiers in Aging Neuroscience reports.

Researcher Dr J. Carson Smith, of the University of Maryland, said: 'We found that physical activity has the potential to preserve the volume of the hippocampus in those with increased risk for Alzheimer's disease, which means we can possibly delay cognitive decline and the onset of dementia symptoms in these individuals.

'Physical activity interventions may be especially potent and important for this group.'

He added that future research is needed to work out how exercise and genetics interact to lower the risk of Alzheimer's.

And that more evidence could lead to those with a family history of the disease being 'prescribed' exercise.

Dr Smith said: 'We do not yet have the level of exercise needed to justify this approach specifically for Alzheimer's prevention but exercise certainly cannot harm, so should be prescribed regardless.'

Alzheimer's and other forms of dementia affect some 800,000 Britons and the number is predicted to double in a generation as the population ages.

APOE-E4 raises the risk of the disease up to ten-fold and up to 40 per cent of people who develop Alzheimer's in old have the gene.