Your fate, at least when it comes to dementia, is not inextricably bound to your genes, it seems.
According to a new study published in the journal JAMA, adopting a healthy lifestyle can wind back the risk of dementia conferred by a bad deal from the genetic lottery.
“This research delivers a really important message that undermines a fatalistic view of dementia,” says lead researcher David Llewellyn, an epidemiologist at the University of Exeter, UK.
“Some people believe it’s inevitable they’ll develop dementia because of their genetics. However, it appears that you may be able to substantially reduce your dementia risk by living a healthy lifestyle.”
The researchers took a deep dive into the UK Biobank, an open-access treasure trove for health researchers that contains genetic and health-related data for half a million Brits, collected between 2006 and 2010.
They homed in on people aged 60 and over, and of European descent, who had no signs of dementia at enrolment and for whom genetic info was available. That whittled the numbers down to just under 200,000.
Those people were classed as having low, intermediate or high genetic risk for dementia based on the findings of an earlier Alzheimer’s study (which only included people of European background, hence the limited remit of the current study).
The researchers also calculated a “healthy lifestyle score” for participants based on whether they smoked, did exercise, had a good diet and had only moderate alcohol consumption.
The group was followed for a median period of eight years to log whether a diagnosis of dementia was made.
The bad news is that, yes, your genes have a loud say in whether you get dementia. Just 0.63% of those with low genetic risk did, but that figure nearly doubled – to 1.23%– for people with high genetic risk.
It is also a bit grim if your habits veer from the health conscious. Having an “unfavourable” lifestyle upped the risk of dementia by 35% compared to people with a healthy lifestyle.
But for people able to nail a healthier lifestyle, things look decidedly rosier. When the researchers looked at people in the high genetic risk category for dementia, having a healthier lifestyle lowered their dementia risk by a not inconsiderable 32% against those with less healthy habits.
“This is the first study to analyse the extent to which you may offset your genetic risk of dementia by living a healthy lifestyle,” says co-author Elżbieta Kuźma, also from the University of Exeter’s Medical School.
“Our findings are exciting as they show that we can take action to try to offset our genetic risk for dementia. Sticking to a healthy lifestyle was associated with a reduced risk of dementia, regardless of the genetic risk,” she said.
When it comes to dementia, however, physical health is but one part of the equation.
A separate study published in the journal JAMA Neurology asks whether having an active mind across the lifespan might also keep dementia at bay.
The theory of “cognitive reserve” holds that stimulating the noggin in early and middle age puts brainpower in the bank for later life, breeding resilience to age- and disease-related brain changes.
However, according to the researchers, who were led by Xiuying Qi and Weili Xu from Tianjin Medical University in Tianjin, China, hard evidence for a protective effect of cognitive reserve on dementia is limited.
Their study aimed to fill that knowledge gap. They analysed data from just over 1600 adults, with no cognitive impairment, who were enrolled in The Rush Memory and Aging Project. It’s an ongoing study trying to pin down the risk factors for neurodegenerative diseases such as dementia.
Participants – 75% women and with a mean age of just under 80 – were given a “cognitive reserve score” based on brownie points they’d notched up over the years.
That meant tallying how long they stayed at school and the extent to which they did mind-challenging activities such as reading books, writing letters and visiting libraries.
But cognitive reserve also hinges on social factors. The researchers allocated points for going to restaurants and sporting events, visiting friends, making trips and going to church. And they totted up the size of each person’s network of family and friends.
Participants were followed for a mean period of six years to see if they got dementia.
The benefits of an active mind, it would seem, rival those of healthy habits.
People with the highest levels of cognitive reserve had a nearly 40% reduction in dementia risk compared to those with the least cognitive reserve.
But perhaps one of the most surprising findings came from a slightly macabre quirk in the study. Many participants – more than 600 in fact – volunteered their brains for autopsy.
The researchers measured the presence of typical brain changes of dementia, including blood vessel changes as well as the amyloid plaques seen in Alzheimer’s disease. Even when those changes were present, the team found, having a high cognitive reserve could still ward off dementia.
The result is a valuable lesson for people keen to stay sharp in their later years.
“Our findings suggest that accumulative educational and mentally stimulating activities enhancing cognitive reserve throughout life might be a feasible strategy to prevent dementia, even in people with high Alzheimer disease or vascular pathologies,” the authors conclude.
Paul Biegler is a philosopher, physician and Adjunct Research Fellow in Bioethics at Monash University. He received the 2012 Australasian Association of Philosophy Media Prize and his book The Ethical Treatment of Depression (MIT Press 2011) won the Australian Museum Eureka Prize for Research in Ethics.
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