FRIDAY, June 26, 2015 (HealthDay News) -- Changes in cognition and memory that precede obvious symptoms of Alzheimer's disease may begin decades prior to disease onset, according to a study published online June 24 in Neurology.
Kumar Rajan, Ph.D., of the Rush University Medical Center in Chicago, and colleagues conducted a study involving 2,125 African-Americans and European-Americans from Chicago. The participants were an average age of 73. None were diagnosed with Alzheimer's at the start of the study, and each completed tests of episodic memory, executive function, and global cognition every three years over nearly two decades.
During the study period, 23 percent of the African-Americans and 17 percent of the European-Americans developed Alzheimer's. Those who had the lowest test scores were at greater risk for the disease. After the first year, those with lower test scores were about 10 times more likely to develop Alzheimer's than those with the best scores. These odds increased as the scores dropped below average, the researchers found.
"A general current concept is that in development of Alzheimer's disease, certain physical and biologic changes precede memory and thinking impairment," Rajan said in a news release from the American Academy of Neurology. "If this is so, then these underlying processes may have a very long duration. Efforts to successfully prevent the disease may well require a better understanding of these processes near middle age."