Can individuals with Down syndrome help cure Alzheimer’s?

Experts are turning to people with Down syndrome to help find a cure for Alzheimer’s. According to recent research, Down syndrome patients offer the most promising link for understanding how the body develops Alzheimer’s disease and may one day aid in the development of a preventative Alzheimer’s medication.

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“People with Down syndrome represent the world’s largest population of individuals predisposed to getting Alzheimer’s disease,” said to NPR, director of the Memory Disorders Clinic at UCSD, Michael Rafii. “By the age of 40, 100 percent of all individuals with Down syndrome have the pathology of Alzheimer’s in their brain.”

The reason for this has to do with the underlying cause of Down syndrome. The condition is the result of a genetic abnormality–an extra copy of chromosome 21.

The link deepens when experts look at chromosome 21 and Alzheimer’s disease; that particular chromosome is linked to amyloid production, the substance associated with sticky plaques in Alzheimer’s. It makes sense then for individuals with Down syndrome–thus an extra copy of chromosome 21–to have a higher rate of Alzheimer’s development.

Individuals with Down syndrome typically begin to experience the full scale memory issues associated with Alzheimer’s by the time they reach age 60. Rafii demonstrates this cognitive decline by discussing a patient by the name of Irma, whom he followed as a case study.

“You can see her signature is on the line, it’s clear, she wrote it in script,” Rafii said, referring to 1999 when he began following Irma. “[By 2005, though, she has switched to large block letters. By 2009, Irma was misspelling her name. By 2011,] there are only a few characters written that resemble letters,” he stated. “And in the very last year it’s completely blank.”

Irma’s condition was the result of amyloid plaques building up around nerve cells in the brain, a process that was accelerated because of the presence of an extra chromosome 21. According to the Alzheimer’s Association, amyloid plaques are the end formation of protein and beta-amyloid. These plaques clump together at nerve synapses, disabling cells and triggering inflammation, eventually leading to cognitive dysfunction.

Experts hope if they can find a cure for amyloid plaques in individuals with Down syndrome they may be able to transfer that knowledge to the rest of the population. In theory, controlling amyloid production in an individual with twice the susceptibility means controlling it in a person with a single chromosome 21 would be that much simpler.

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“This approach to treating Alzheimer’s disease might apply to all of us,” said William Mobley, chairman of the neuroscience department at UCSD. “Imagine someday a drug that we all start taking when we’re 25 so we never get Alzheimer’s disease.”

Clinical trials are underway for medications just for that purpose, but experts indicate they are years away from any kind of mass-market Alzheimer’s preventative. Right now, researchers are focusing on understanding how amyloid production impacts brain health as well as looking out for easy ways to screen for Alzheimer’s disease before symptoms manifest.