Lifetime risks of developing Alzheimer's disease dementia vary considerably by age, gender and the presence of any signs or symptoms of dementia, a new study by Alzheimer's & Dementia: The Journal of the Alzheimer's Association reports.

These are the first lifetime risk estimates for Alzheimer's that take into account what are believed to be biological changes in the brain that occur 10 to 20 years before memory and thinking symptoms appear. These early changes are referred to as preclinical Alzheimer's disease.

Researchers provide the example of a 90-year-old female with amyloid plaques having a lifetime risk of Alzheimer's disease of only 8.4 percent, compared to a 65-year-old female with amyloid plaques who has a lifetime risk of 29.3 percent. The shorter life expectancy of the older person explains the lower lifetime risk for this person over that of the 65 year old.

That same 65-year-old with amyloid plaques has a 10-year risk of Alzheimer's disease dementia of 2.5 percent. Lifetime risks for females are generally higher than males because they live longer. The authors state that the lifetime and 10-year risks are an indication of the potential that someone will develop Alzheimer's disease dementia based on their age and screenings for amyloid deposits, neurodegeneration and presence or absence of MCI or any combination of those three.

Paper: “Estimation of lifetime risks of Alzheimer's disease dementia using biomarkers for preclinical disease”

Reprinted by materials provided by the Alzheimer's Association