“Knockout” Head Injuries Linked to Parkinson’s, But Not Alzheimer’s

July 15, 2016

(Scientific American) – A large-scale analysis of three separate studies published this week in JAMA Neurology found no association between unconsciousness-causing traumatic brain injuries (TBI) and Alzheimer’s disease or general dementia—but it did find a strong association between TBI and Parkinson’s disease. “I can’t decide if the positive or negative findings are more surprising,” says one of the study’s investigators, physician and Alzheimer’s researcher Paul Crane at the University of Washington. The positive association his team found between Parkinson’s and TBI was not entirely novel, but Crane says the magnitude of the link was unexpected. The researchers found the risk of Parkinson’s rose threefold for people whose head injuries had caused them to go unconscious for more than an hour.