Aβ, Tau Absolved of Causing Mild Cognitive Impairment in Parkinson’s

Why do only some people with Parkinson’s disease decline cognitively? Scientists have proposed various theories, including that coincident Alzheimer’s pathology is to blame. Researchers led by Joseph Winer and William Jagust at the University of California, Berkeley, tested this by measuring amyloid and tau levels in vivo with PET. In the December 11 JAMA Neurology, they reported that PD patients with mild cognitive impairment had no more tau tangles on average than did cognitively normal PD patients or healthy controls. “From this study and others, there is converging evidence that tau pathology does not relate to the cognitive decline in Parkinson’s,” Winer said. The study excluded people with Parkinson’s disease dementia.