Athleticism And Body Weight Tied To Als And Other Motor Neuron Diseases

ALS, sometimes called "Lou Gehrig's Disease" after the famous baseball player whose career was cut short by the disease, has been associated with many patients who were lean throughout their lives as well as being athletes, said Lewis P. Rowland, MD, with the Neurological Institute in New York, and a co-author of the study.

The case-control study compared variables including BMI (body mass index), age at onset of the disease, sex, slimness, and participation in varsity athletics of 279 patients with motor neuron disease and 152 with other neurological diseases.

"We found the odds of having motor neuron disease was 2.21 times higher in subjects who reported they had always been slim than in those who did not. Further, motor neuron disease was 1.70 times higher in patients who reported they had been varsity athletes," said Scarmeas.

According to the Centers for Disease Control, only 14 percent of U.S. adults aged 18 to 29 years participate in physical activities, even fewer qualify for varsity sports. Rowland said, "The numbers of our motor neuron disease patients (38 percent) and controls (26.7 percent) were both higher than these population estimates.

It is not known what contributes to the higher concentration of motor neuron disease in top athletes. Researchers have hypothesized that vigorous physical activity might increase exposure to environmental toxins, facilitate the transport of toxins to the brain, increase the absorption of toxins, or increase the athlete's susceptibility to motor neuron disease through added physical stress.

Rowland said more could be learned in follow-up studies that look in depth at the nature of the activity, the environmental setting, and the intensity.

He added that "thousands and thousands of slim athletes never develop ALS. Why a tiny few of them do is unknown. We do know that there is no justification to avoid athletics in an attempt to avoid motor neuron diseases."

Previous studies that looked at a possible association between heavy labor or competitive athletics and ALS were inconclusive. However, they involved much smaller sample sizes and did not include a group of controls for comparison data.

The American Academy of Neurology, an association of 18,000 neurologists and neuroscience professionals in 90 countries, is dedicated to improving patient care through education and research. For more information about the American Academy of Neurology, visit its web site at http://www.aan.com.