New Lifetime Risk Estimates for Alzheimer's and Dementia

By Todd Neale
BOSTON, March 21 -- For women who reach age 55, the remaining lifetime risk of developing Alzheimer's disease is 17%; for men it's 9%, according to unpublished data from the Framingham Heart Study.
Risk is greater for developing any dementia, including Alzheimer's, after 55 -- at 21% for women and 14% for men, Sudha Seshadri, M.D., of Boston University Medical Center, and colleagues, reported in the Alzheimer's Association's 2008 Alzheimer's Disease Facts and Figures.
A woman's risk is higher because "their longer life expectancy increases the time during which they could develop Alzheimer's disease or other dementia," according to the authors.
For the 78 million baby boomers born from 1946 through 1964, this means that about 10 million men and women can expect to develop Alzheimer's disease, with 14 million in line for a diagnosis of dementia.
These estimates are conservative, the researchers said, because of the high threshold used in the Framingham Heart Study for categorizing patients as having dementia.
A patient was required to have a score of 1 or higher on the Clinical Dementia Rating Scale, and to have had the symptoms for at least six months.
Alzheimer's disease was diagnosed using the standard criteria from the National Institute of Neurological and Communicative Disorders and Stroke and the Alzheimer's Disease and Related Disorders Association.
As deaths from other causes such as heart disease, cancer, and stroke decline, the authors said, "unless there are new treatments to prevent Alzheimer's and other dementias, the remaining lifetime risk of Alzheimer's and dementia will increase substantially in the future."
In 1997, the researchers had reported the remaining lifetime risk of Alzheimer's disease and dementia in patients who lived to be at least 65 (Neurology 1997; 49: 1498-1504).
For a 65-year-old man, the remaining lifetime risks of Alzheimer's disease and dementia were 6.3% and 10.9%, respectively. For a 65-year-old woman, the corresponding risks were 12% and 19%.
Additional source: Alzheimer's AssociationSource reference: Alzheimer's Association "2008 Alzheimer's disease facts and figures."