Sedentary older adults with no genetic risk factors for dementia may be just as likely to develop the disease as those who are genetically predisposed, researchers, including one of Indian origin, have warned.
The study which followed more than 1,600 Canadians over five years sheds new light on the relationship between genes, lifestyle risk factors and dementia.
Researchers also found that while carriers of a variant of the 'apolipoprotein E' genotype are more likely to develop dementia, inactivity dramatically increases the risk for non-carriers.
"The important message here is that being inactive may completely negate the protective effects of a healthy set of genes," said Jennifer Heisz, assistant professor at McMaster University in Canada.
"Given that most individuals are not at genetic risk, physical exercise may be an effective prevention strategy," she said.
About 47.5-million people worldwide are living with dementia. That number is expected to surge to 115.4 million by the year 2050, researchers said.
With no known cure, there is an urgent need to explore, identify and change lifestyle factors that can reduce dementia risk, they said.
"Although age is an important marker for dementia, there is more and more research showing the link between genetic and lifestyle factors," said Parminder Raina from McMaster.
"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," said Raina.
"A physically active lifestyle helps the brain operate more effectively. 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 do not know'," said lead author Barbara Fenesi from McMaster.
The study was published in the Journal of Alzheimer's Disease.