It has been known for a number of years individuals with Down Syndrome are at an increased risk for Alzheimer’s disease later in life, though the reason for the connection was elusive. Now, a growing body of evidence suggests the presence of amyloid-beta protein plaques between nerve cells in the brain found in people with Down Syndrome are likely to blame.
Because those protein plaques characteristic of Down Syndrome are also found in patients developing Alzheimer’s disease, understanding how those plaques form and how they affect the brain may offer ways for researchers to develop treatments to slow or cure the condition all together.
“It’s a tantalizing and provocative question: Do people with Down Syndrome hold the key to the mystery of Alzheimer’s development?” Dr. Brian Skotko, co-director of the Down Syndrome Program at the Massachusetts General Hospital in Boston, said in a telephone interview. “And what can we learn from those with Down Syndrome that will benefit the rest of the population?”
While experts have narrowed the link between Down Syndrome and Alzheimer’s disease significantly the exact connection remains mysterious, though many speculate it has to do with the extra genes present in an individual with Down Syndrome.
Research suggests these genes are responsible for the plaque tangles between nerve cells, and according to the Alzheimer’s Association, studies show that by age 40, the brains of almost all individuals with Down Syndrome have significant high levels of amyloid-beta protein plaques.
Only approximately 40 to 50 percent of those individuals develop Alzheimer’s disease however, a fact which only adds to the Alzheimer’s mystery.
But how do individuals without Down Syndrome develop Alzheimer’s if there is a relationship between the two conditions?
Experts indicate the cause likely has something to do with the precursor protein for amyloid-beta, which is encoded on the 21st chromosome, the same chromosome people with Down Syndrome get an extra copy of.
Further research will hopefully uncover the exact mechanism of this chromosome at work in both Down Syndrome patients and those with unrelated Alzheimer’s disease.
“We’ve learned that prevention and treatment in the earliest stages is probably our best way to battle this disease,” Cindy Lemere, an associate professor of neurology at the Harvard Medical School and Brigham and Women’s Hospital, told TODAY.
“And we know that everybody with Down Syndrome will eventually develop Alzheimer’s disease – or at least the changes in the brain. So we know that this is now another population where we can perhaps go in and test therapies very early in the disease as a prevention.”
Alzheimer’s disease currently affects more than 5 million people in the United States and is the sixth leading cause of death. Approximately 200,000 of individuals with the condition are under the age of 65. For individuals with Down Syndrome, onset of Alzheimer’s is usually prior to the age of 40.