A link between Alzheimer's and Parkinson's disease

A link between Alzheimer's disease and Parkinson's disease has been long been suspected by clinical observations, but an understanding of the molecular mechanisms involved has been missing. In September 25 online Proceedings of the National Academy of Sciences, Eliezer Masliah and colleagues from the University of California at San Diego, La Jolla show evidence of a common molecular pathway between these two diseases.

Masliah et al. studied strains of transgenic mice engineered to express human amyloid precursor protein (hAPP), human α-synuclein (hSYN), or both. These proteins are known to accumulate in Alzheimer's and Parkinson's, respectively.

They found that mice that expressed both proteins showed severe deficits in learning and memory and developed motor deficits sooner than mice that only expressed hSYN. These mice also had more α-synuclein neuronal inclusions than mice that only expressed α-synuclein. In addition, the inclusions in doubly transgenic mice were fibrillar, while those...