Model Estimates Lifetime Risk of Alzheimer's Dementia Using Biomarkers

A study published in Alzheimer's & Dementia took brain biomarkers into account for the first time to determine that the lifetime risk of developing Alzheimer's dementia varies according to age, gender, and whether any signs or symptoms of dementia are present, reports Medical Xpress . "What we found in this research is that people with preclinical Alzheimer's disease dementia may never experience any clinical symptoms during their lifetimes because of its long and variable preclinical period," notes Ron Brookmeyer from the University of California, Los Angeles School of Public Health. "The high mortality rates in senior populations are also an important factor as individuals are likely to die of other causes." Following their review of existing scientific literature, the researchers generated a computerized mathematical model to determine a person's likelihood of progressing in the continuum of the disease. They based their estimates on the transition rates from the studies and from U.S. death rates data based on age and gender. As an example, Brookmeyer cites a 90-year-old female with amyloid plaques with only an 8.4 percent lifetime risk of Alzheimer's, versus a 65-year-old female with amyloid plaques with a 29.3 percent lifetime risk. The lower lifetime risk for the 90-year-old is explained by her shorter life expectancy, while the 65-year-old with amyloid plaques has a 10-year risk of Alzheimer's dementia of 2.5 percent. The researchers say the lifetime and 10-year risks offer an indication of the potential that someone will develop Alzheimer's dementia based on their age and screenings for amyloid deposits, neurodegeneration, and presence or absence of MCI or any combination of those three. Having all these biomarkers puts people at the highest risk of developing Alzheimer's.