Dementia, which currently has no cure, affects some 50 million people worldwide. That roughly equates to 5 percent of the over-60 population. By 2050, this number is predicted to hit 152 million.
To try to tackle what is proving to be a bit of a public health crisis, the World Health Organization (WHO) has released a new set of guidelines on how to best reduce your risk – or, at the very least, delay the disease's progress. The guide, based on decades' worth of research, outlines 12 potential factors and assesses the science behind them.
The basic takeaway is advice that reads like a list of all those things we know we should do but don’t necessarily want to do – regular exercise, eating healthily, not smoking, and drinking less.
"In the next 30 years, the number of people with dementia is expected to triple," WHO Director-General Dr Tedros Adhanom Ghebreyesus said in a statement.
"We need to do everything we can to reduce our risk of dementia. The scientific evidence gathered for these Guidelines confirm what we have suspected for some time, that what is good for our heart, is also good for our brain."
While age is by far the biggest risk factor, the team behind the report stresses that it "is not a natural or inevitable consequence of aging". Indeed, multiple studies have identified an association between dementia and various "risk" factors, e.g. excessive alcohol consumption, tobacco use, and physical inactivity.
Certain medical conditions – diabetes, hypertension, obesity, and depression – have also been linked to the development of dementia. As has social isolation and cognitive inactivity.
So, what do the guidelines suggest? The team issued strong recommendations in favor of regular exercise, tobacco cessation, and the management of conditions like hypertension and diabetes.
However, a strong recommendation does not necessarily mean there is compelling evidence that something has a direct effect on dementia risk but that the authors were "confident that the desirable effects of the intervention outweigh any undesirable effects".
There is moderate evidence to link "hazardous and harmful drinking" to dementia. And in terms of diet, there is moderate evidence to suggest that keeping to the Mediterranean diet may protect your cognitive function.
"The Mediterranean diet is the most extensively studied dietary approach, in general as well as in relation to cognitive function," the authors write. However, they add that the cognitive benefits of the diet require high (not moderate) adherence.
The authors say that while social support and involvement are important for general health and wellbeing, there is not enough evidence to link social isolation to dementia.
Likewise, there is little to support the benefits of cognitive training or to show that hearing loss has a detrimental effect on cognition. (Although hearing aids should be offered if needed regardless.)
One thing they actively advised against was the use of vitamin B and E, polyunsaturated fatty acid, and multi-complex supplementation.
While the guidelines offer a good set of rules to live by – not just to reduce your chances of dementia, but to improve your general health – there are limitations.
Many recommendations had a low or moderate quality of evidence, heavily suggesting that more research is needed. Indeed, the BMJ reports, independent researchers have critiqued the guidelines for a lack of evidence proving the effectiveness of the recommendations.
"Little hard evidence is available to show that modifying environmental factors modify the risk for dementia strongly," said Bart De Strooper, director of the UK Dementia Research Institute.
"Absence of evidence is not evidence of absence, and hypertension, obesity, diabetes, social isolation, and depression are all strongly correlated with poor health and decreased life expectancy, although the effects on the prevention of dementia needs further clarification."