Subtle symptoms of Alzheimer’s disease may show up much earlier than we thought. Researchers are working on a memory and thinking test that could tell middle-aged people if they’re likely to be diagnosed with Alzheimer’s within the next two decades.
"The changes in thinking and memory that precede obvious symptoms of Alzheimer's disease begin decades before," Kumar Rajan of Rush University Medical Center says in a statement. "While we cannot currently detect such changes in individuals at risk, we were able to observe them among a group of individuals who eventually developed dementia due to Alzheimer's." Their findings were published in Neurology last week.
A total of 2,125 European-American and African-American residents of Chicago, who were 73 years old on average, agreed to take a memory and thinking skills test every 3 years for 18 years. The participants were all 65 years or older at the start of the study, and none of them had Alzheimer's. Over the course of the study, however, 23% of the African-American recruits and 17% of the European-American recruits developed the disease.
The participants who had lower overall test scores showed an increased risk of developing Alzheimer’s: During the first year, people who scored lower were 10 times more likely to be diagnosed than people with higher scores. Furthermore, for tests taken 13–18 years before the final assessment, one unit lower in performance of the standardized cognitive test score was linked to an 85% greater risk of future dementia. As Rajan explains, this indicates that even subtle declines in cognitive function affect future risk.
As a person develops Alzheimer’s, certain physical and biological changes may precede noticeable impairments in memory and thinking. "If this is so, then these underlying processes may have a very long duration," Rajan adds. And the key to preventing the disease may be in understanding the processes that take place before a person reaches old age.
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