Professor Kaarin Anstey, a member of the WHO’s Guideline Development Group (GDG) and Director of the UNSW Ageing Futures Institute, said a lot has changed since the guidelines were first released.
Back in 2019, 12 risk factors were considered. This time, there were 20.
Some that previously lacked sufficient evidence to make recommendations for interventions — such as social engagement and hearing loss — now have conditional recommendations as evidence has increased. Others, like air pollution, appear for the first time.
On the other hand, the guidelines made a conditional recommendation against menopausal hormone therapy (MHT) for women aged 65 and older (based on very low certainty evidence), and found there was insufficient evidence to recommend either for or against MHT for those under 65.
“After reviewing the available evidence, the GDG determined that the only population for which sufficiently robust data existed was postmenopausal women aged 65 years and older. Within this population, evidence consistently demonstrated little to no difference – irrespective of formulation – on reducing the risk of cognitive decline or dementia,” the guidelines state.
There was also not enough evidence to recommend treatment for depression to prevent cognitive decline – despite it being a known risk factor.
“A lot of it’s just the evidence base. Surprisingly there’s not many randomised controlled trials of treatment of depression that look at cognition as an outcome,” Professor Anstey said.
The same was true for interventions for management of sleep, TBI, vision impairment, HIV, and stroke, which all had insufficient evidence for intervention.
Here’s an overview of some of the key changes.
While the previous guidelines recommended structured, computer-based cognitive activity, or ‘brain training,’ the new guidelines expand this to include ‘cognitive stimulation.’
“I think this is actually much more accessible for most people. So, it’s reading books, participating in games, undertaking a course, learning a new language, playing an instrument, purposely engaging in some sort of cognitively stimulating activity,” Professor Anstey said.
“I think that’s much more practical,” she said. “Not everybody wants to sit at a computer and do brain training.”
As for whether structured cognitive activity provides additional benefit over other cognitive stimulation, Professor Anstey said the two hadn’t been directly compared.
Social activity interventions were not recommended in the previous guidelines due to lack of evidence. This time around, the WHO issued a conditional recommendation, noting that although the certainty of evidence was “very low,” social disconnection – including social isolation and loneliness – significantly negatively affects health and wellbeing.
The caveats reflect the quality of evidence – for example different studies use different outcome measures, and there could be reverse causation where those with some cognitive impairment withdraw socially, Professor Anstey noted.
However, “there’s no harm in recommending this… and overall, when they consider everything, they think that on balance, the recommendation favours the intervention,” Professor Anstey said.
The guidance includes a conditional recommendation for weight loss interventions in midlife (ages 40–65) for people with obesity.
“Initially when people did weight loss research, they weren’t looking at cognition as an outcome, but now there’s a growing body of evidence showing that there are cognitive benefits of weight loss interventions in middle age,” Professor Anstey explained.
Overweight and obesity in middle age is a well-established risk factor for dementia, whereas later in life it does not seem to increase the risk, she noted.
The recommendation does not yet extend to pharmacological weight‑loss therapies, which were not evaluated.
The new guidelines make a conditional recommendation to address hearing loss to reduce the risk of cognitive decline. Evidence remains low as trials have been mixed, but there’s enough to support the recommendation, Professor Anstey says, stressing that the guidelines were specifically looking at preventing cognitive decline. “A lot of these things you would do anyway for other reasons,” she noted.
There were also conditional recommendations based on largely observational studies that reducing the risk of household and ambient air pollution may reduce the risk or incidence of cognitive decline or dementia.
No changes were made to the existing recommendations for physical activity, diet, alcohol, smoking or vascular risk factors – but the guidelines now explicitly recognise the importance of addressing multiple risk factors through multi-domain interventions that look at three or more factors, Professor Anstey said.
“Brain health has to be a holistic health approach in line with the other non-communicable diseases,” she said.
“And middle age is also very critical for managing the risk factors and intervening. But it’s no longer just one or two things. It’s a lot of things.”
Professor Anstey’s team is actively recruiting nationally for a multi-domain trial that looks at lifestyle risk reduction for people aged 65 or older with subjective cognitive decline or mild cognitive impairment.
“It’s conducted completely online, so anybody from remote and regional areas can participate, and people who meet our criteria get free exercise physiology, dietary advice, cognitive training, and an e-learning course.”
“And it’s all about addressing those modifiable risk factors in that group of people who are either very concerned about their memory and have noticed some changes or who actually meet a criteria for mild cognitive impairment.”
Dr Marita Long, GP medical advisor for Dementia Australia also welcomes the revised WHO guidelines. She adds while there are still no curative treatments for dementia, prevention remains one of the key strategies we have to address the leading cause of death in Australia.
The CogDrisk assessment tool (developed by Professor Anstey and UNSW colleagues) is a validated dementia risk assessment tool that GPs can offer to their patients, particularly in midlife, to help identify and modify any risk factors they may have in line with the reviewed WHO guidelines.
More information
Risk reduction of cognitive decline and dementia: WHO guidelines, second edition
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