Landmark Study' Shows Brain Cells Revamp Their DNA, Perhaps Sparking Alzheimer's Disease

A study published in Nature suggests Alzheimer's could be promoted by the genomic scrambling, or somatic recombination, of neurons, according to Science . The researchers analyzed neurons from the donated brains of six healthy seniors and seven individuals who had the noninherited form of Alzheimer's. The team tested whether the neurons exhibited different versions of the gene for the amyloid precursor protein (APP), the source of the plaques in the brains of people with Alzheimer's. According to the analysis, the neurons appear to carry thousands of APP variants. Some changes involved switching single nucleotide bases, while others jettisoned whole chunks of DNA with the remaining sections knitting together. In addition, neurons from people with Alzheimer's contained about six times as many APP gene variants as did those from the healthy people. Alterations in the neurons of people who had Alzheimer's included 11 mutations that occur in the inherited forms of the disease, while cells from the subjects who died without the disease lacked these mutations. The implication is that while somatic recombination may benefit neurons by enabling them to generate various APP versions that enhance brain functions, it also may encourage Alzheimer's in certain people by producing damaging versions of APP or by harming neurons in other ways.