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Down Syndrome and Alzheimer’s Disease

down syndrome

With improved health care, persons with Down syndrome (DS) now routinely reach 60 years of age. (As recently as 1983, the average lifespan of a person with DS was 25 years). But with living longer has come an increased risk of developing Alzheimer’s disease (AD).

Risk estimates vary, but the National Down Syndrome Society says that nearly 25 percent of individuals with DS over the age of 35 show signs of Alzheimer’s-type dementia, a percentage that dramatically increases over time. Almost all persons with DS develop dementia by the age of 60.

Loss of connectivity between brain neurons, called synaptic failure, is a hallmark of AD, and linked to reduced levels of synaptic proteins. Though persons with DS are at markedly higher risk of developing AD, there have been few studies to investigate synapse dysfunction in their brains.

A new study by researchers at UC San Diego School of Medicine, published in Alzheimer’s & Dementia, the journal of the Alzheimer’s Association, does just that, finding that a common subset of synaptic proteins were reduced both in persons with AD and persons with both DS and AD, but not in persons with just DS or where the triple mutation that causes DS does not triple a gene called APP.

Additional mouse model studies confirmed the findings.

The research, led by William Mobley, MD, PhD, Distinguished Professor of Neurosciences, advances efforts to identify clinical biomarkers of AD, which can help to define disease status in those with AD or those at risk for AD.

— Scott LaFee