Healthy living could mitigate Alzheimer’s risk

Diet, exercise linked to lower risk, study finds

dementia isn’t an inevitable part of aging, even for those carrying multiple genetic risk factors for the brain-ravaging disease, a new study suggests.

researchers who followed nearly 200,000 people found those at high genetic risk for dementia, but who didn’t smoke, exercised regularly, drank in moderation and ate a mediterranean-leaning diet lowered their dementia risk by a third.

the findings challenge the fatalistic view of the memory-robbing illness, researchers said, and add to emerging theories that whatever is good for the heart is most probably good for the brain.

“a healthy lifestyle was protective, even for the people who had a bad luck of the draw with their genetic inheritance,” said dr. John Haaga, of the u.s. national Institute on aging, one of the study’s funders.

the study analyzed data from 196,383 people from the uk biobank study, making it a considerably larger sample than anything done before. all were aged 60 and older, and free of dementia, at the start of the study.

all were also genotyped, meaning their dna was analyzed for genetic features linked to the risk of dementia, and then grouped into categories according to risk: high, intermediate or low.

People were also given a score based on four recognized risk factors for dementia (smoking status, physical activity, diet and alcohol consumption).

“they told us a lot about themselves,” said lead author dr. david llewellyn, from the university of Exeter medical school. For example: whether or not they smoked; how much fish they ate (the more the better); how much red meat they ate; how many servings of fruits and vegetables they ate in a particular day; and how much they drank in a typical week.

People were then grouped into favourable, intermediate or unfavourable lifestyle categories.

overall, people with a high genetic risk and an unhealthy lifestyle were nearly three times more likely to develop dementia compared to people with a low genetic risk and healthy habits.

but good habits lowered the risk regardless of a person’s genetic vulnerability. among people with a high genetic risk, 1.13 per cent of those with a healthy lifestyle developed dementia after eight years of follow-up, versus 1.78 per cent of those with less wholesome habits.

according to llewellyn, non-smokers, people who limited their alcohol consumption (moderate consumption was defined as no more than one drink a day for women, or two per day for men), those who ate at least three servings of fruits and vegetables daily, and those who ate relatively little red meat scored highest on the lifestyle scale.

It’s not just any one of these lifestyle changes, but the combination that appears to protect the mind.

the underlying mechanisms aren’t entirely clear, though there are several plausible hypotheses, llewellyn said from los angeles, where he presented his group’s work at the alzheimer’s association International conference. the human brain is a hungry organ. It requires a rich and constant supply of oxygen and glucose, and small disruptions to the blood supply to the brain make it vulnerable to dementia, he said.

more than 419,000 canadians aged 65 and older are diagnosed with dementia, two-thirds of them women. It is the only major cause of death in Western countries without effective treatment.

the study, published in this week’s Journal of the american medical association, has several caveats. It doesn’t prove cause and effect, lifestyle factors were self-reported, people were followed up for a median of eight years only and some cases of dementia aren’t recorded in medical records or death registries.