The report was compiled by the first Lancet Commission on Dementia Prevention and Care, which brought together 24 experts from around the world to review scores of studies and synthesise them into a model showing how lifestyle modification could reduce dementia risk.
About 47 million people have dementia worldwide, and that number is projected to triple by 2050. The global cost of dementia in 2015 was estimated to be $818 billion, a figure also expected to rise with the number of cases.
There is insufficient published research on the prevalence of dementia in South Africa, but according to SA Medical Journal a survey of individuals around the age of 60 years in residential homes found 7.9% with dementia; this was not, however, a population prevalence study.
The University of the Free State, which investigated dementia in an urban black community, reported a higher than expected preliminary prevalence of about 6% in a small sample of 200 older persons.
In South Africa there is a also a growing epidemic of HIV-associated dementia in older residents. According to current figures the prevalence of HIV-associated dementia is 15-30% in untreated populations with late-stage disease, presenting with neurocognitive impairments, emotional disturbances, and motor dysfunction.
The prevalence in individuals receiving highly active antiretroviral therapy (HAART) is 10%, with an annual incidence of 1%.
According to the latest Lancet Commission, the report identifies nine risk factors over a person’s lifespan, including years of education before age 15; hypertension, hearing loss and obesity in middle age; and smoking, depression, physical inactivity, social isolation and diabetes in late life.
The Lancet team considered each factor separately and also looked at how they related to one another to calculate how much modification of each could potentially affect a person’s dementia risk.
In the past decade, research has increasingly pointed to controllable lifestyle factors as integral to reducing the risk of cognitive decline.
Researchers believe that, as with heart disease, combating dementia is likely to require a multipronged, or “cocktail” approach combining drugs and lifestyle changes.
“The message is that conditions like dementia are not immutable and are substantially modifiable by the environment,” said Lon Schneider, professor of psychiatry and the behavioural sciences at the Keck School of Medicine at the University of Southern California and a co-author of the Lancet report.
Noting that modifying all nine factors could reduce the risk by 35%, he said, “Compare that to how we’re developing drugs to treat dementia.
“Dementia is not a condition that’s ever going to be such that a single drug can be considered a cure for the illness.”
Lifestyle modification is inexpensive, he said, adding that a 35% reduction of risk is “far larger than anything you can ever expect for drugs.” - The Washington Post