In surveying previous Alzheimer's literature and analyzing compiled health records, researchers isolated and emphasized seven risk factors most associated with Alzheimer's, including: diabetes, midlife hypertension, midlife obesity, physical inactivity, depression, smoking, and low educational attainment.
By addressing these risk factors, the medical researchers say, roughly a third of all Alzheimer's cases could be prevented.
The new study both builds and revises a 2011 study by Deborah Barnes of the University of California, San Francisco, that suggested one in two cases were preventable.
"Our hope is that these estimates will help public health professionals and health policy makers design effective strategies to prevent and manage this disease," said Barnes, who also co-authored the more recent study, which was published this week in the journal The Lancet Neurology.
"Simply tackling physical inactivity, for example, will reduce levels of obesity, hypertension and diabetes, and prevent some people from developing dementia as well as allowing a healthier old age in general," explained Carol Brayne, a professor of public health medicine at Cambridge. "It's a win-win situation."
Meanwhile, a separate study out of UC San Francisco suggests a link between sleep disorders and an increased risk of dementia.
The number of cases of Alzheimer's and other forms of dementia are expected to increase from 101 million today to 227 million by 2050.