A traumatic brain injury (TBI) that involves loss of consciousness is not associated with the development of Alzheimer’s disease (AD) later in life but is associated with later onset of Parkinson’s disease (PD) and accumulation of Lewy bodies, a new study published online July 11 in JAMA Neurology suggests. The lack of association between TBI and AD, even among those carrying the APOE ε4 allele, contrasts with an influential paper published in Neurology in 1995 in which researchers found a 10-fold increased risk for AD among APOE ε4–positive patients who had sustained a TBI. The study did find that a single blow to the head resulting in lost consciousness for more than an hour may lead to more than a three-fold increased risk for PD decades later.
Offering her views to Medscape Medical News, Beth Vernaleo, PhD, associate director of research programs, Parkinson’s Disease Foundation, said that although most people who experience head injury won’t develop PD, the new study “may provide clinicians with an additional diagnostic tool.” For example, she said, “asking patients about history of head injury, amongst other symptoms and risk factors, may prove a valuable means of ascertaining the likelihood of a Parkinson’s diagnosis.”
Read more at: http://www.medscape.com/viewarticle/866210#vp_3