Compared to people with other neurological diseases, people with ALS are more likely to have a history of being athletic and slim, according to a new study from Columbia Presbyterian Medical Center in New York.
The study, presented in April at the American Academy of Neurology annual meeting in Denver, could hold clues to what causes ALS. But it doesn't mean that physical fitness increases the risk of ALS, say the study's main authors, neurologists Lewis Rowland and Nikolaos Scarmeas.
"It doesn't mean that people in general should not exercise or that people with ALS should not exercise," emphasizes Rowland, who served as director of the Eleanor and Lou Gehrig MDA/ALS Center at Columbia from 1987 to 2000.
The real message, Rowland and Scarmeas say, is that future studies should take a closer look at the connection between athletics and ALS, which kills the motor neurons in the spinal cord.
Baseball, boxing, football, soccer …
Hints of the connection have been floating around for years. Boxer Ezzard Charles, baseball player Catfish Hunter and, of course, baseball icon Lou Gehrig all died of ALS.
Three players from the San Francisco 49ers had the disease in the 1980s, and Glenn Montgomery of the Seattle Seahawks lost his life to ALS in 1998. In the last year, the Italian Olympic Committee began investigating an apparent spike in the disease among Italian soccer players.
Rowland says his own ALS patients, many of whom had been athletes or always had been slim, also inspired him to do the study.
He and Scarmeas asked 279 people with ALS or other motor neuron diseases to report their athletic involvement, body type, height and weight prior to their first symptoms. Compared to 152 people with other neurological diseases, people in the ALS group were:
- 1.7 times more likely to have once been varsity athletes
- more than twice as likely to report always having been slim
- 2.5 times more likely to score 25 or below on the body mass index (a measure of slimness)
There are several possible explanations for those findings, says Scarmeas, who primarily studies Alzheimer's disease. Athletes might be exposed to more toxins, such as performance-enhancing drugs or the fertilizers used on playing fields, or they could suffer repeated injuries to their motorneurons.
Alternatively, "there could be a [genetic] factor that gives people athletic abilities when they are young and a higher risk for ALS when they grow older," he says.
For now, he cautions, "All of this is hypothetical. The study just provides observations that hopefully will stimulate further research."