Scientists have made a genetic risk score that they suggest could find exactly which adults have a chance of developing Alzheimer’s disease years before it begins to affect the person. Elizabeth C. Mormino, Ph.D., of Massachusetts General Hospital in Charlestown, and her coworkers published how they used the score to look for potential signals of Alzheimer’s disease in healthy adults starting at the age of eighteen.
The scientists recently announced their results in the journal Neurology. Alzheimer’s disease is one of the worst diseases of the twenty-first century. There are more than five million adults in the United States, and over the next three decades, this amount is predicted to triple. The study authors have stated that the pathophysiologic processes of Alzheimer’s disease are thought to happen at least ten years before the symptoms begin to hit.
“Given that current clinical trials are testing whether therapies can slow memory and thinking decline among people at risk for the disease, it is critical to understand the influence of risk factors before symptoms are present,” Mormino says.
Researchers are not yet sure of the exact cause of Alzheimer’s disease, but what they do know is that genetics is a factor. For instance, studies have indicated that people who have a form of the APOE gene, known as APOE e4, are more likely to develop the disease.
“In addition to the APOE gene, to date 21 common genetic variants have been associated with Alzheimer’s disease in large genome-wide association study meta-analyses,” the researchers state.
For their research, the scientists did what they call a polygenic risk score. They did this by analyzing the genomes of more than 166 adults with dementia and 1,026 adults that do not have dementia. They developed the score on the basis of what genetic variants each adult, both with dementia and without, had. In addition, they also looked and studied the participants for various indicators of Alzheimer’s disease, including a fall in thinking, memory, and the size of the hippocampus, the brain part linked to memory.
Also, the scientists applied the polygenic risk score to 1,322 healthy adults between the ages of eighteen and thirty-five and studied the volume of their hippocampus so that they can see if there is a link. Among older adults who did not have dementia, the team saw a higher polygenic risk score was linked to worse memory and a smaller hippocampus at study baseline. The risk score accounted for about two percent of the variance in memory and 2 percent of hippocampal volume variance.