Couch potatoes 'at highest risk of dementia'

    

• Sedentary over-65s are as likely to develop dementia as those with genetic risk

• Inactivity dramatically increased the risk for non-carriers, researchers found

• 47.5 million live with Alzheimer's now and 115.4 million are expected to by 2050

• Experts suggest that physical activity may prevent the onset of the disease

Couch potatoes are just as likely to get dementia as those born with the Alzheimer's gene, a new study claims.

This means that even without any genetic risk factors, over-65s who rarely exercise are among the most likely to develop the disease.

Currently 47.5 million people worldwide are living with dementia and that number is is set to increase to 115.4 million by 2050 due to the aging population.

But experts warn the rising rate of physical inactivity could drive up that figure even more.

With no known cure, scientists are now looking to develop new dementia prevention strategies that focus on increasing physical exercise in older adults.

The recent study followed 1,600 Canadian adults over the course of five years.

Researchers found that although carriers of a variant of the 'apolipoprotein E' genotype are more likely to develop dementia, inactivity dramatically increased the risk for non-carriers.

For those who carried the gene, the odds of developing dementia were not significantly different between exercisers and non-exercisers.

Co-author Jennifer Heisz, an assistant professor in the Department of Kinesiology at McMaster University, said: 'The important message here is that being inactive may completely negate the protective effects of a healthy set of genes.

'Given that most individuals are not at genetic risk, physical exercise may be an effective prevention strategy.'

Research has shown that physical exercise may be able to prevent or slow down the symptoms of Alzheimer's disease.

Scientists suggest getting 150 minutes or more of exercise each week, adding brain-boosting omega-3 fats such as salmon to your diet and social engagement. 

Co-author Parminder Raina, professor in the Department of Health Evidence and Impact at McMaster said: 'Although age is an important marker for dementia, there is more and more research showing the link between genetic and lifestyle factors.

'This research shows that exercise can mitigate the risk of dementia for people without the variant of the apolipoprotein genotype. However, more research is needed to determine the implications from a public health perspective.'

In a separate ongoing study, researchers are comparing the possible benefits of high-intensity training (HIIT) versus moderate continuous training (MCT) and stretching in older adults.

'A physically active lifestyle helps the brain operate more effectively,' said Barbara Fenesi, lead author and a postdoctoral fellow at McMaster University. 

She added: 'However, if a physician were to ask us today what type of exercise to prescribe for a patient to reduce the risk of dementia, the honest answer is "We really don't know".'

Mary Kekatos