August 11, 2015
Low scores on tests of memory and thinking skills may predict the onset of Alzheimer’s disease 18 years later, a new study suggests. The findings highlight how Alzheimer’s disease may take decades to unfold, but also raise hopes that new tests and treatments could be developed to combat the disease beginning at its earliest stages.
Researchers at Rush University Medical Center in Chicago tested 2,125 men and women, aged 65 and older, who were part of the ongoing Chicago Health and Aging Project. All were free of Alzheimer’s disease or other forms of dementia at the start of the study.
Over the next 18 years, they were given tests of memory and thinking every three years to look for signs of Alzheimer’s disease. During that time, 442, or 21 percent, developed dementia.
Those who scored lowest on the tests during the first year of the study were 10 times more likely to be diagnosed with Alzheimer’s 18 years later than those with the highest test scores, the researchers found. The findings appeared in Neurology, the medical journal of the American Academy of Neurology.
“The changes in thinking and memory that precede obvious symptoms of Alzheimer’s disease begin decades before,” said study author Kumar B. Rajan of Rush University. “Efforts to successfully prevent the disease may well require a better understanding of these processes near middle age.”
The tests used in this study were general and applied to large groups of people; no single test can currently predict who will go on to develop Alzheimer’s disease. But they merit further research, the authors say, and someday more effective tests to diagnose Alzheimer’s at its earliest stages may become available.
Dr. Rajan said he plans to study whether mentally stimulating tasks like doing crossword puzzles or learning a new language can improve test scores, and in turn slow down the onset of Alzheimer’s disease.
Alzheimer’s still has no cure, and treatments for the disease may ease symptoms for a time but do nothing to stem the disease’s relentless downward progression. Doctors hope that better understanding of what goes wrong in the brain at the earliest stages of the disease may lead to the development of new, more effective treatments. Such treatments may be most effective if given early, before damage to the brain becomes extensive and irreversible, they believe.
If doctors could reliably identify signs that someone is likely to get the disease, they could begin treatment earlier, possibly warding off the onset of Alzheimer’s symptoms years down the road.
Source: Kumar B. Rajan, PhD, Robert S. Wilson, PhD, Jennifer Weuve, MPH, ScD, et al: “Cognitive Impairment 18 Years before Clinical Diagnosis of Alzheimer Disease Dementia.” Neurology Vol 85, pages 107, June 25, 2015.