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expert reaction to WHO Guidelines on risk reduction of cognitive decline and dementia

Reactions to a WHO report which makes life style recommendations which may reduce the chance of developing dementia.

 

 

Prof Bart De Strooper, Director of the UK Dementia Research Institute, University College London (UCL), said: 

“The WHO report summarizes a series of recommendations for a healthy life style, which may also have beneficial effects on the incidence of dementia. Overall little hard evidence is, however, available that modifying environmental factors modify the risk for dementia strongly.  Absence of evidence is not evidence of absence and hypertension, obesity, diabetes, social isolation, depression are all strongly correlated with poor health and decreased life expectancy, although the effects on the prevention of dementia needs further clarification. What is clear however is that the major risk for a dementing disorder like Alzheimer’s Disease is the genetic predisposition of the patient which is the main focus of the Dementia Research Institute. We need urgently medications to control these pathologies.”

 

 

Dr Carol Routledge, Director of Research at Alzheimer’s Research UK, said:

“With a rapidly ageing population in the UK and across the world, many people are keen to know the steps they can take to enjoy their later years in good health. Dementia is now the UK’s leading cause of death, yet only 34% of adults recognise there is anything they can do to reduce their risk of the condition.

“The findings clarify what we already know about dementia risk, including the value of physical activity and not smoking. While observational studies have identified a link between dementia risk and factors like depression and hearing loss, the report highlights a lack of sufficient evidence that treating these conditions effectively reduces the risk of cognitive decline.

“Sadly, there will always be individuals who address many or all of these risk factors and still develop dementia. Genetic predisposition plays an important role in many people’s risk of diseases like Alzheimer’s, and while we cannot change the genes we inherit, taking the steps outlined in this report can still help to stack the odds in our favour.

“This valuable resource, which has been reviewed and developed by leading experts based on high-quality evidence, represents the best possible source of information. We now need to see these recommendations shared through NHS Health Checks in midlife, as well as through government-led risk reduction campaigns to reach as many people as possible.”

 

Prof Tara Spires-Jones, UK Dementia Research Institute Programme Lead and Deputy Director, Centre for Discovery Brain Sciences, University of Edinburgh, said:

“A group of experts convened by the World Health Organisation has made recommendations for reducing the risk of cognitive decline and dementia.  This is important because dementia affects around 50 million people worldwide and we currently do not have effective treatments for the diseases that cause dementia.  Accumulating evidence suggests that brain changes that cause dementia begin many years before symptoms. The WHO has looked at the available evidence and made recommendations that some lifestyle changes, in particular increasing exercise before any cognitive symptoms are present, can reduce dementia risk.  Other recommendations have a less strong evidence base but may have evidence that they do not increase risk or harm, and can therefore be recommended safely, although their impact on risk is less certain.  While some people are unlucky and inherit a combination of genes that makes it highly likely they will develop dementia, many people have the opportunity to substantially reduce their risk by living a healthy lifestyle. If people around the world follow these recommendations, we should be able to reduce the burden of dementias.”

 

Dr Fiona Carragher, Chief Policy and Research Officer at Alzheimer’s Society, said: 

“Dementia is the biggest health challenge of our generation, so the WHO’s clear commitment to spearheading the global fight against the condition through a public health approach is to be welcomed.

“It’s estimated a third of dementia cases could be prevented, and this report provides the best available prevention advice. But there’s still a lot of work to do – every three seconds someone in the world develops dementia, and there’s still a lack of firm evidence on how exactly we should tackle the many risk factors of dementia. That’s why we’re funding the UK’s largest study focused on mid-life dementia risk factors to begin to address this evidence gap.

“Policy-makers and governments across the globe should take on board WHO’s recommendations and prevention advice. They must also unite in supporting further research to develop more specific, personalised risk reduction advice.” 

 

Prof Robert Howard, Professor of Old Age Psychiatry, University College London (UCL), said:

“In the absence of any effective treatments for established dementia, these guidelines will be eagerly read by health professionals and members of the public who are all desperate to have some evidence-based guidance on how to prevent the appearance of the condition.

“The guidelines are based on a comprehensive and carefully conducted review of the published literature and are sensible but unsurprising. Keep on doing the things that we know benefit overall physical and mental health (smoking cessation, reduce harmful alcohol drinking, treat hypertension, eat a healthy balanced diet and lose weight if you are obese), but understand that the evidence that these steps will reduce dementia risk is not strong. Like many colleagues, I already tell my patients that what is good for their hearts is probably good for their brains.

“The essential problem with dementia prevention strategies is that the evidence supporting individual components is weak. Any evidence that we do have tends to come from observational studies, where association cannot imply causation, and from interventional studies where the methodology has not been of the high standard we would demand if we were investigating the effectiveness of a new drug.

“These guidelines do an important job in highlighting the weakness of the available evidence and should be a call to arms for investment in the highest quality interventional dementia prevention trials. We are probably decades away from treatments to slow or stop established dementia. Prevention would be so much better than a distant cure.”  

 

Prof Tom Dening, Director of the Centre for Old Age and Dementia, Institute of Mental Health, University of Nottingham, said:

“No surprises really. The report takes a uniform approach across the 12 questions and provides clear recommendations where appropriate. Like most of the research on dementia risk factors, it is difficult to see clearly the effects of social inequality, but nearly everything that is modifiable tends to favour people in better socio-economic circumstances, e.g. diet, access to facilities for physical activity, social interactions.

“The negative recommendation, advocating that people do not use vitamin or dietary supplements (unless they are needed for a clinical problem) is welcome, and it is to be hoped that it saves lots of people from wasting their money.

“One limitation of this research and similar studies is that they focus very much on medical risks. This is fair enough and most of the research literature is about these issues. However, it ignores the social aspects of dementia – to have dementia implies that there is an impairment of social functioning, not just cognitive impairment. Thus, there may be aspects of society that can affect whether a person becomes functionally impaired (or not). One important aspect of this is technology. If we can’t operate our email or do online shopping, we start to become impaired. I think that WHO should perhaps also have considered the impact of changing technology upon the nature and presentation of dementia, and some guidance about how technology might help would have been very useful.”

 

Prof Robert Stewart, Professor of Psychiatric Epidemiology & Clinical Informatics, Institute of Psychiatry, Psychology & Neuroscience, King’s College London:

“These guidelines provide a welcome assembly of evidence from decades of research. We know that dementia becomes much more common with increasing age, but lots of older people do not develop dementia. We know a lot more than we used to about risk factors for dementia, particularly about other conditions or lifestyles that may affect risk. This is very important because there may be ways in which dementia could be delayed or prevented through modifying risk lifestyles or treating risk conditions.

“On the other hand, there are frequent reports about behaviours, lifestyles or medications that might prevent dementia; despite media publicity, these reports often come from single studies that are not confirmed, creating confusion. So there’s a real need to bring studies together for expert review and this report provides what is likely to be the most reliable advice at this point in time. One of the difficulties, as raised frequently in these guidelines, is that dementia risk does tend to be lowest in people who are healthiest earlier in life. This makes it easy to give ‘stay healthy’ advice – which summarises most of the conclusions in this report; however, it can be hard to examine these interventions adequately in randomised trials on dementia prevention, which is why the quality of evidence is often quite low.” 

 

Prof Gill Livingston, Professor of Psychiatry of Older People, UCL, said:

“These are timely and important guidelines to begin globally tackling the only known ways of preventing memory impairment and subsequent dementia, that is using psychological, social and medical interventions to decrease risk factors.

“With the strides in reduction of premature mortality, there are more older people. Therefore, there are an increase in the number of people living with dementia. However, dementia is not an inevitable consequence of reaching older ages. In the US and European countries there have already been a decrease of around 20%, in the percentage of older people, who develop dementia. This is related to changes in lifestyle and in medical interventions. In other countries there are increases in the percentages of older people with dementia and higher numbers of people with risk factors such as hypertension (high blood pressure), increases in cigarette smoking or obesity.

“There are huge implications in the real word – dementia is the condition that adults aged over 50 are most concerned about developing. Knowing about risk factors gives individuals an opportunity to reduce their chances of getting dementia and policy makers evidence to work on. Following these recommendations will decrease your chance of developing dementia but not to zero. However, even in those people who get it, it will probably be delayed for several years. While genetics are still at play, in our Lancet commission of 2017±, we found that 7% of the known causes of dementia were genetic compared to 35% which were potentially modifiable risk factors.

“The group have spent time reviewing and integrating research (it is explicitly built on our Lancet commission and an American report on risk factors) and has been led by the data and tried to build on the existing evidence.

“There are some limitations. As it has taken time to put together, inevitably some of the most recent evidence is omitted. In addition, the authors state that in some instances, even when the quality of evidence was low or very low, it was agreed that if the recommendation would be of general benefit, and this was seen to outweigh the harms, it may still be rated as strong. This seems to be inconsistently applied. There is good, particularly recent, randomised controlled trial evidence that energetically treating hypertension in people aged over 50 reduces the chance of cognitive impairment and probably subsequent dementia; but this recommendation is graded as conditional. Evidence about interventions for alcohol does not come from randomised trials but from observational studies and is still rated as conditional. Additionally, in hearing loss, there are several very recent observational studies which show that people who have hearing aids and use hearing aids are not at an increased risk of dementia but their use is not recommended at all, which isn’t necessarily consistent.

“It is difficult to distinguish between lack of evidence that intervention decreases the risk (say with obesity) and lack of evidence that decreasing the risk reduces cognitive impairment and dementia (say for example social interventions around isolation- studies on this have not been done and theoretically are very hard to do). Also, there is no formal calculation of the cost and benefits.”

 

 ‘Risk reduction of cognitive decline and dementia’ by WHO was published at 14:00 UK time on Tuesday 14th May.

 

Declared interests

Prof Bart De Strooper: Bart De Strooper is director of the UK Dementia Research Institute, and has collaborations with the pharmaceutical industry. 

Dr Carol Routledge: No conflicts of interest. 

Prof Tara Spires-Jones: I have no conflicts of interest with this paper. For completeness, I am on the Scientific Advisory Board of Cognition Therapeutics and receive grant funding from 2 companies.

 Prof Robert Howard: No competing interests.   

Prof Tom Dening: No conflicts of interest. 

Prof Robert Stewart: ‘I’ve received research funding in the last 5 years from Roche, Janssen, GSK and Takeda; however, I don’t think any of those firms (or the projects funded) have any relationship to the material in the report.’

 Prof Gill Livingston:  Prof Livingston was a member of the External Review Group

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