Mayo Clinic study links concussion to later Alzheimer's disease
Having a serious concussion could be a risk factor for developing Alzheimer's decades later — though not everyone with head trauma will lose their memory, a new study suggests.
A team from the Mayo Clinic in Rochester Minn., conducted brain scans on 448 older Minnesotans who had no signs of memory problems and 141 who did. Roughly 17 percent in both groups had suffered a brain injury earlier in life involving some loss of consciousness or memory.
Those who had no signs of memory problems had normal brain scans, regardless of their history of brain injury. Scans of those with memory problems and a history of brain injury were five times more likely to show a buildup of a brain protein long associated with Alzheimer's disease, said study author Michelle Mielke, an associate professor of epidemiology and neurology at the Mayo Clinic.
The study, published online on Friday in the journal Neurology, examined people in their 70s and 80s who reported having an earlier head trauma — in most cases 50 or 60 years earlier when they were adolescents. In those days, only the sickest people went to the doctor, so the head injuries were probably quite significant, Mielke said.
This is one of the first studies to take advantage of new technology, allowing brain scans to measure the buildup of a protein called beta amyloid, long associated with Alzheimer's. Most previous studies of the connection between Alzheimer's and head injury had looked only at cadavers.
“In my view, these findings are consistent with the idea that traumatic brain injury may lead to amyloid accumulation and Alzheimer's disease,” said Richard Lipton, director of the Division of Cognitive Aging and Dementia and the Montefiore Headache Center at the Albert Einstein College of Medicine in New York City.
More research is needed, he cautions, to help explain how one causes the other. “To more fully explore the causal links, we need not just brilliant snapshots but the movies which track brain changes and cognitive changes over time,” he said.
For people worried about their head injuries, the study provides some comfort, Lipton said. Both groups of older adults — impaired and normal — had the same rate of head injury. So clearly, not every head injury leads to Alzheimer's disease, he said.