Repeated concussions may contribute to the development of symptoms that mimic amyotrophic lateral sclerosis, or Lou Gehrig's disease, a controversial group of researchers is suggesting in a provocative new study.
The cause of most cases of ALS—a devastating degenerative disease named after the baseball great who was its most famous victim—is largely a mystery. Only 5% to 10% of those who are diagnosed with ALS carry the distinctive gene mutation known to give rise to the disease: Of the 30,000 Americans who have the disease at any given time, at least 27,000 have no clue as to its origins.The study suggests that the symptoms that felled baseball's beloved "Iron Horse"—spastic movements, muscle weakness and progressive loss of muscle control—may, in part, have been the result of his legendary penchant for playing while injured, including after concussion.
The suggestion that traumatic brain injuries—also called concussions—may contribute to neurodegenerative disease is not new. But a growing body of research has strengthened evidence that concussion may be the catalyst for a wide range of brain diseases, from depression and dementia to Parkinson's disease symptoms and now, movement disorders such as ALS.Dr. Martina Wiedau-Pazos, an expert in movement disorders at UCLA who was not involved with the latest study, called the study's findings "very intriguing," but cautioned that the study was too small to allow clinicians to draw broad conclusions about the prevention or diagnosis of diseases like ALS. Neurobiologist Donald Stein of Emory University, who studies concussion, said the study's authors have raised the possibility that some patients with past brain trauma who appear to have ALS may have another disorder altogether, which may progress differently, and respond to different therapies, than ALS.
"It's very impressive to me," said Stein.
The latest article recounts the first pathology study to find similarities between a concussion-related brain abnormality and abnormalities in the brains of patients with degenerative disease that affects the brain regions responsible for movement. It compares the autopsy slides and samples of 12 professional athletes' brains and spinal cords with those of 12 patients, matched for sex and age, who had died with a diagnosis of ALS, and another 12 patients who were free of brain disease at the time of their death.
All of the athletes whose remains were studied had suffered repeated concussions in their playing years, and suffered from chronic traumatic encephalopathy, in which the same kinds of tangles as are found in Alzheimer;'s disease patients appear throughout the brain. In the case of all but one of the athletes studied, remains had been donated to Boston University's Center for the Study of Traumatic Encephalopathy.
The study found distinctive protein abnormalities in the brains and spinal cords of three of the athletes who, in addition to traumatic encephalopathy, had developed motor symptoms that were diagnosed as ALS. The same array of distinctive abnormalities was found in the brains of all of the patients who had died of ALS, and none of those who had died with intact brain function.
"The play of contact sports, such as boxing, football and hockey, might be associated" with the protein abnormalities seen in the brains of the motor-impaired brain-injury victims as well as those whose impairment was the result of disease, the authors—led by Dr. Ann C. McKee—wrote. "Whether repetitive head trauma alone provokes these neurodegenerative cascades, or only in association with certain genetic constellations remains to be determined," they added.Traumatic brain injury is often called "the silent epidemic" because in spite of the fact that 1.5 million Americans yearly are thought to suffer traumatic brain injury, the effect of such brain injuries on the nation's health—as well as that of the individuals affected—has, until recently, been largely ignored. With as many as 360,000 U.S. troops returning from Iraq and Afghanistan having suffered a traumatic brain injury during service, that has begun to change.