The brain disorder, known as chronic traumatic encephalopathy (CTE), is marked by a buildup of abnormal proteins in the brain. It can cause memory loss, trouble concentrating, impulsive and erratic behavior, depression, and eventually dementia.
CTE is often compared to being "punch drunk," says Alexander P. Lin, PhD, an investigator at the Center for Clinical Spectroscopy at Brigham and Women's Hospital in Boston.
CTE can only be definitively diagnosed by autopsy. But in a study of five retired pro athletes, Lin and colleagues found that a specialized imaging technique called magnetic resonance spectroscopy may help diagnose CTE at an earlier stage.
Often called a virtual biopsy, "magnetic resonance spectroscopy samples brain tissue and measures brain chemistry," Lin tells WebMD. It's performed using a regular MRI scanner with software modifications.
The hope is that doctors can eventually diagnose CTE at any early stage so patients can change their behavior before lasting damage occurs, he says.
Brain Chemical Changes in Former Athletes
Lin and colleagues studied retired athletes -- three football players, a wrestler, and a boxer --- aged 32 to 55 who had suffered a number of concussions over a period of three to 15 years and five men of similar ages who hadn't suffered head trauma and had no cognitive problems. All underwent magnetic resonance spectroscopy.
"There were definite brain chemical changes in the [athletes]," Lin says.
Among the findings:
- Levels of choline, a marker of tissue damage, were 12.5% higher in the brains of former athletes than in the healthy volunteers.
- Levels of glutamate were 12% higher in the athletes. When glutamate levels are too high, brain cells die off, Li says.
- Levels of gamma-aminobutyric acid (GABA), a brain chemical involved in memory, were 8% lower in the former athletes than in the healthy volunteers.
The findings were presented at the annual meeting of the Radiological Society of North America.
Recreational Athletes, Military Personnel Can Be Affected Too
"While the findings are obviously very preliminary, we are starting to see chemical changes in the brains" of people who suffer repeated head blows, Lin says.
He notes that there are drugs that lower glutamate levels and increase GABA levels that may help people if CTE is diagnosed earlier.
While the study only involved pro athletes, being able to diagnose CTE earlier could also benefit people who engage in recreational sports as well as people in the military, who sometimes suffer blast and other head injuries, says Max Wintermark, MD, of the University of Virginia in Charlottesville. He was not involved with the research.
According to the CDC, an estimated 3.8 million sports- and recreation-related concussions are diagnosed in the U.S. each year. Many more people suffer so-called subclinical concussions -- injuries that may not be diagnosed as concussions but have similar effects, Lin says.
Recently, an autopsy revealed evidence of CTE in 21-year-old Owen Thomas, a University of Pennsylvania football captain who committed suicide in April 2010.
This study was presented at a medical conference. The findings should be considered preliminary as they have not yet undergone the "peer review" process, in which outside experts scrutinize the data prior to publication in a medical journal.