CANADIAN researchers have found that being inactive can contribute to developing dementia, even in people who have no generic risk factors.

Following on from a previous study into the importance of exercise, the McMaster University researchers have shed new light on genes, lifestyle risk factors and dementia.

About 47.5 million people live with dementia. The researchers expect this number to rise to 115.4 million by 2050.

Without a known cure, scientists are exploring factors to help dementia risk.

"The important message here is that being inactive may completely negate the protective effects of a healthy set of genes," McMaster University professor and study co-author, Jennifer Heisz said.　

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

The study's lead author, Doctor Barbara Fenesi, said being active helps the brain operate better.

"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'," she added.

Perhaps once the researchers complete their current research into comparing the benefits of high-intensity training versus moderate continuous training and stretching in older adults, there will be advice from them on recommended exercise programs.