Study shows why people with Down’s syndrome develop Alzheimer’s disease

Down-syndrome-adult — Processes that lead to changes in the brains of people with Down’s syndrome are similar to the changes that cause dementia in Alzheimer’s patients, a study finds

People with Down’s syndrome typically develop Alzheimer’s disease by middle age, including the amyloid plaques that are the hallmark of the disease. The extra copy of the Î²-amyloid precursor protein (APP) gene on chromosome 21 is thought to contribute to this neuropathology, but the precise mechanisms are unclear.

Writing in Cell Reports
^[1] (online, 23 October 2014), researchers led by Huaxi Xu, from Sanford-Burnham Medical Research Institute, La Jolla, California, say they have identified a key protein that regulates Î²-amyloid. Levels of “sorting nexin 27” protein are significantly reduced in people with Down’s syndrome, they say, which indirectly (via the gamma-secretase enzyme) promotes Î²-amyloid production and amyloid plaque formation.

“Our study establishes a molecular mechanism for Î²-amyloid-dependent pathogenesis in both Down’s syndrome and Alzheimer’s disease,” write Xu and co-authors.