Editor's note: This story was updated on July 25, 2018.
More than one-third of dementia cases might be prevented by addressing nine lifestyle factors that have been tied to an increased risk for the disease, according to a report published in The Lancet.
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The researchers presented their findings earlier this month at the Alzheimer's Association International Conference in London.
Dementia: This century's 'biggest killer'
Researchers estimate that in 2015, about 47 million individuals worldwide were living with dementia, and care for the disease cost about $818 billion. According to the Los Angeles Times' "Science Now," the number of people with dementia worldwide is expected to increase threefold by 2050.
Doug Brown, director of research at Alzheimer's Society, said, "Though it's not inevitable, dementia is currently set to be the 21st Century's biggest killer."
For the new report, researchers on the Lancet Commission on Dementia Prevention, Intervention, and Care reviewed existing literature and performed new meta-analysis into risk factors that had not been previously assessed, such as social isolation and hearing loss. The researchers looked at the benefits of building a "cognitive reserve," or strengthening the brain's networks to support function later in life despite damage, according to BBC.
Lead author Gill Livingston of University College London explained, "Although dementia is diagnosed in later life, the brain changes usually begin to develop years before." According to Livingston, the researchers "looked at the whole life course," which allowed them to identify "when ... things [such as social isolation and hearing loss] make a difference."
Separately, Maria Carrillo, chief science officer at Alzheimer's Association, called the report "the most comprehensive overview of data on prevention, intervention, and care ever conducted."
Key findings on prevention
The researchers identified nine lifestyle factors that together make up 35 percent of the risk for developing dementia worldwide. Those nine factors are:
- Midlife hearing loss, which makes up 9 percent of dementia risk;
- Early life education, which makes up 8 percent;
- Later life smoking, which makes up 5 percent;
- Later life depression, which makes up 4 percent;
- Later life physical inactivity, which makes up 3 percent;
- Later life social isolation, which makes up 2 percent;
- Midlife hypertension, which makes up 2 percent;
- Later life diabetes, which makes up 1 percent; and
- Midlife obesity, which makes up 1 percent.
The researchers added that, based on their findings, people who continue to learn as they age are more likely to establish additional cognitive reserves.
In comparison, according to the researchers, the ApoE-e4 gene, which predisposes carriers to the disease, accounts for 7 percent of dementia risk.
The researchers said they lacked sufficient data to include several lifestyle factors, such as alcohol use, sleep patterns, diet, visual impairment, or air pollution. Citing the likely influence of those factors, Livingston said, "The contribution of lifestyle is probably quite a bit more than 35 percent, but we're just going with what the evidence has shown."
Livingston added that while "people commonly think" being fluent in a second language affects dementia risk, the data show "being bilingual was not protective." Previous findings on language and dementia risk are probably explained by the individual's education, she said.
Key findings on care
The report also included several recommendations about how to care for individuals who have dementia, Medscape reports. Those recommendations include:
- Assess the cognitive capacity of patients at end of life to make sure they can make decisions regarding their care;
- Discuss the future with patients and their caregivers, including an assessment about a patient's ability to make decisions at the time of diagnosis;
- Protect people who have dementia from various risk factors, such as self-neglect and exploitation;
- Provide support for family caregivers, including interventions for depression;
- Tailor dementia care to the individual and his or her cultural needs and preferences;
- Take advantage of technological interventions to improve care delivery, but do not allow such interventions to replace social interaction;
- Treat neuropsychiatric symptoms, including agitation, low mood, or psychosis with psychological, social, environmental, and—when needed—pharmacologic management; and
- Treat the cognitive symptoms of people who have Alzheimer's or dementia with Lewy bodies—protein deposits that develop in the nerve cells in the parts of the brain involved in memory, movement, and thought—by offering them cholinesterase inhibitors "at all stages," or memantine for severe dementia.
Implications and next steps
In terms of next steps, Livingston said, "What we need to do now is establish what the recipe looks like for the combination of the nine items that have been found relevant, which of these findings are the most actionable, then make the public heath recommendations and make sure these reach groups that need them the most—those with the lowest socioeconomic status."
From our ExpertsHow to better manage dementia patients across the care continuum
Separately, Lon Schneider—an Alzheimer's disease specialist at the University of Southern California Keck School of Medicine and author on the report—said the commission has generated a roadmap for reducing the worldwide burden of dementia. According to Schneider, pathways the report suggests, such as efforts to keep children in school and to manage blood pressure in midlife, would not only help address dementia, but would benefit society in other ways as well.
Livingston said, "Acting now will vastly improve life for people with dementia and their families and, in doing so, will transform the future of society." She added, "Our results show it is never too early or never too late to make lifestyle changes that will make a difference."
What about that other report on Alzheimer's?
The Lancet report partly counters some conclusions in another recent report on Alzheimer's, which was released by the U.S. National Academies of Sciences, Engineering, and Medicine (NASEM), Medscape reports.
The NASEM report concluded that three key strategies aimed at preventing cognitive decline are supported by "encouraging," but not necessarily "high-strength, evidence." Those strategies included cognitive training, controlling blood pressure, and physical activity.
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When representatives from both groups of researchers were asked to account for the differences between their findings, the researchers said they approached the issue from different perspectives. The NASEM report assessed interventional studies to find evidence about the benefits of various strategies, while the Lancet team assessed preventive strategies, focused on cognitive impairment and dementia in addition to Alzheimer's, and relied more heavily on epidemiologic data.
Schneider said, "Our report was probably more comprehensive on the possibilities for prevention and, yes, we were probably more aggressive in our interpretation of what can be done."
Separately, Ron Petersen, a physician at the Mayo Clinic who is part of the NASEM committee, said The Lancet report's "projections are very interesting but are more hypothetical than ours." He continued, "We do not disagree with them and welcome this new report—it will help drive funding for further research and action in tackling this enormous problem of cognitive impairment and dementia in the aging population around the world" (Hughes, Medscape, 7/20; Walsh, BBC, 7/20; Healy, "Science Now," Los Angeles Times, 7/20; Mayo Clinic, accessed 7/25).
Get 5 strategies to provide cost-efficient Alzheimer’s and dementia care
Over 5.3 million Americans currently suffer from Alzheimer’s disease and related memory disorders and the Alzheimer’s Association predicts this number to triple to 13.8 million by 2050. On top of rising demand, reimbursement processes fail to meet the complex needs of these patients who require multifaceted care.
Here are the five key strategies that a program of any scope and size can implement to provide cost-efficient Alzheimer’s and dementia care.