Researchers have suspected for a while that people who sustain a single traumatic brain injury are more likely to develop Alzheimer's-like symptoms later in life.
Now a University of Pennsylvania scientist has helped bolster that theory with some hard evidence: irregular protein deposits in samples of human brain.
The brains came from 39 people who had had a moderate or severe traumatic brain injury at some point but died from another cause, anywhere from one to 47 years later.
Nearly half of the brain samples were marked by deposits called tangles, one of the hallmarks of Alzheimer's disease.
Such deposits also were present in a fair percentage of brain samples taken from other people who had not suffered a brain injury, but those tangles were not as widely distributed throughout the brain.
Moreover, the tangles were far more evident in the brains of young people who'd had one brain injury, found in patients as young as 27.
A good portion of both the injured and uninjured brains also contained plaques, another deposit linked with Alzheimer's disease. But the plaques in the uninjured brains were diffuse; those in the once-injured brains were far more likely to have a fibrous quality like steel wool.
The study was the work of Douglas H. Smith, director of the Center for Brain Injury and Repair at Penn's Perelman School of Medicine, in collaboration with colleagues at the University of Glasgow. It was published in the journal Brain Pathology.
"It's really suggestive that this is a progressive process" that can harm people decades after the initial injury, Smith says.
Separately, a new study of more than 280,000 older veterans found that those who suffered a traumatic brain injury were twice as likely to suffer from dementia within seven years.
And last week, the Ivy League took action to protect its football players, who, while they may not be subjected to "severe" brain injury, can receive repeated lesser blows with the potential for long-term impact. The league said it would limit players to two full-contact practices per week.
- Tom Avril
