One-Third Of Dementia Cases Could Be Prevented, Report Says

One-third of cases of dementia worldwide could potentially be prevented through better management of lifestyle factors such as smoking, hypertension, depression, and hearing loss over the course of a lifetime, according to a new report.

Across the globe, about 47 million people were living with Alzheimer's and other forms of dementia in 2015. That number is projected to triple by the year 2050 as the population ages. Health care costs associated with dementia are enormous, with an estimated $818 billion price tag in 2015.

The new study, published in The Lancet and conducted by the first Lancet Commission on Dementia Prevention and Care, brought together 24 international experts to review existing dementia research and provide recommendations for treating and preventing the devastating condition.

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"Dementia is the greatest global challenge for health and social care in the 21st century," lead study author Professor Gill Livingston, of University College London, told CBS News. "The purpose of the commission was therefore to address it by consolidating the huge strides and emerging knowledge as to what we should do to prevent dementia and intervene and care for people with dementia."

There is currently no drug treatment to prevent or cure dementia. But the report highlights the impact of non-drug interventions and identifies nine modifiable risk factors through various stages of life — beginning in childhood — that affect the likelihood of developing dementia.

To reduce the risk, factors that make a difference include getting an education (staying in school until over the age of 15); reducing high blood pressure, obesity and diabetes; avoiding or treating hearing loss in mid-life; not smoking; getting physical exercise; and reducing depression and social isolation later in life. About 35 percent of dementia cases are attributable to these factors, the analysis found. Removing them could then theoretically prevent 1 in 3 cases.

In contrast, finding a way to target the major genetic risk factor, a gene called the apolipoprotein E (ApoE) ε4 allele, would prevent less than 1 in 10 cases – or about 7 percent.

"There's been a great deal of focus on developing medicines to prevent dementia, including Alzheimer's disease," commission member Lon Schneider, M.D., a professor of psychiatry and the behavioral sciences at the Keck School of Medicine of USC, said in a statement. "But we can't lose sight of the real major advances we've already made in treating dementia, including preventive approaches." Schneider presented the findings at the Alzheimer's Association International Conference (AAIC) 2017.

Of the nine risk factors, the researchers identified the three most common ones that could be targeted for dementia prevention.

The first is increasing education in early life, which the report estimated could reduce the total number of dementia cases by 8 percent if all people worldwide continued their education until over the age of 15.

The researchers note that not completing secondary education could raise dementia risk by reducing what's referred to as "cognitive reserve." It's believed that education and other mentally stimulating tasks help the brain strengthen its networks so it can continue to function at a higher level even if it starts to decline later in life.

For the first time, the researchers also identified hearing loss as a major modifiable risk factor for dementia. They estimated that reducing hearing loss in mid-life could also reduce the number of dementia cases by 9 percent if all people were treated.

Livingston notes that research surrounding hearing loss and dementia is still in early stages and the link likely has something to do with the social isolation that can come with losing the ability to hear.

"They may work in similar ways as they reduce the chance of interactions and conversations, which are like exercise for the brain and enrich it and predispose to depression," she said.

It's not clear from medical research yet whether using hearing aids can counteract this risk.

Additionally, the researchers found the number of dementia cases worldwide could be reduced by 5 percent if all people stopped smoking. It's particularly important to stop smoking later in life, they say, to reduce neurotoxins and improve heart health, which in turn improves brain health.

Other interventions likely to reduce dementia rates include increased physical activity and treating high blood pressure and diabetes.

The study authors say the report can offer guidance on ways to reduce the risk of dementia throughout life and improve the care for those living with the disease.

"This includes providing safe and effective social and health care interventions in order to integrate people with dementia within their communities," Schneider said. "Hopefully this will also ensure that people with dementia, their families and caregivers, encounter a society that accepts and supports them."

It's important to note that lifestyle interventions will not delay or prevent all dementia cases. But the researchers say they are hopeful that the report will help shift more focus to concrete steps that can be taken to help avoid the disease.

"We hope that this report will feed into individual nations' dementia policies and public health strategies, be used by individual clinicians to inform and improve their practice, and through media publicity inform the general public of what they can do to help avoid dementia, which is the most feared illness in old age."