A peer-reviewed paper to be published Wednesday in a leading journal of neuropathology, however, suggests that the demise of athletes like Gehrig and soldiers given a diagnosis of amyotrophic lateral sclerosis, commonly known as Lou Gehrig’s disease, might have been catalyzed by injuries only now becoming understood: concussions and other brain trauma.  Although the paper does not discuss Gehrig specifically, its authors in interviews acknowledged the clear implication: Lou Gehrig might not have had Lou Gehrig’s disease.  Doctors at the Veterans Affairs Medical Center in Bedford, Mass., and the Boston University School of Medicine, the primary researchers of brain damage among deceased National Football League players, said that markings in the spinal cords of two players and one boxer who also received a diagnosis of A.L.S. indicated that those men did not have A.L.S. They had a different fatal disease, doctors said, caused by concussionlike trauma, that erodes the central nervous system in similar ways.  The finding could prompt a redirection in the study of motor degeneration in athletes and military veterans being given diagnoses of A.L.S. at rates considerably higher than normal, said several experts in A.L.S. who had seen early versions of the paper. Patients with significant histories of brain trauma could be considered for different types of treatment in the future, perhaps leading toward new pathways for a cure.  “Most A.L.S. patients don’t go to autopsy — there’s no need to look at your brain and spinal cord,” said Dr. Brian Crum, an assistant professor of neurology at the Mayo Clinic in Rochester, Minn. “But a disease can look like A.L.S., it can look like Alzheimer’s, and it’s not when you look at the actual tissue. This is something that needs to be paid attention to.”  The finding’s relevance to Gehrig is less clear. But the Yankees legend had a well-documented history of significant concussions on the baseball field, and perhaps others sustained as a battering-ram football halfback in high school and at Columbia University. Given that, it’s possible that Gehrig’s renowned commitment to playing through injuries like concussions, which resulted in his legendary streak of playing in 2,130 consecutive games over 14 years, could have led to his condition.  “Here he is, the face of his disease, and he may have had a different disease as a result of his athletic experience,” said Dr. Ann McKee, the director of the neuropathology laboratory for the New England Veterans Administration Medical Centers and the lead neuropathologist on the study.  Gehrig’s name does not appear in the paper; his case was discussed in interviews merely as an illustration of the new uncertainty surrounding cases resembling his, said Dr. Robert Stern, who serves with Dr. McKee as co-director of Boston University’s Center for the Study of Traumatic Encephalopathy. The cause of his disease will most likely never be determined because his remains were cremated, and now lie in Kensico Cemetery in Valhalla, N.Y.  More significantly, both doctors said, the finding solidifies a long-suspected connection between A.L.S.-like motor disease and head trauma experienced in collision sports and combat.  “People are being misdiagnosed clinically while they’re alive as having A.L.S. when in fact they have a different motor-neuron disease,” Dr. Stern said. He added, “Scientists will be able to get at a faster understanding of the disease in general, and therefore effective treatments, by knowing more about who’s at risk and who’s not.”  According to the A.L.S. Association, up to 30,000 people in the United States currently have A.L.S., an incurably fatal disease among primarily 40- to 70-year-old men that results in the swift and steady atrophy of all voluntary muscle control. Gehrig was its first prominent victim, dying two years after his 1939 diagnosis; some others, like the British physicist Stephen Hawking, now 68, can live for decades with fully functioning brains inside bodies that have wasted away.  The new finding could be double-edged for organizations fighting A.L.S.: it sheds some light on possible causes and research avenues, but also suggests that Gehrig might not have had it.  “It’s extremely interesting — it builds a more interesting picture, but what this all exactly means about how the disease plays out requires further investigation,” said Dr. Lucie Bruijn, the chief scientist for the A.L.S. Association. Dr. Bruijn described Gehrig as “an important fund-raising tool,” similar to the actor Michael J. Fox having Parkinson’s disease.  “It’s a name and a face that get people to understand what kind of a disease this really is,” she said. “It makes it more personal.”  A link between professional football and A.L.S. follows recent discoveries of on-field brain trauma leading to dementia and other cognitive decline in some N.F.L. veterans. Dr. McKee and her group identified 14 former N.F.L. players since 1960 as having been given diagnoses of A.L.S., a total about eight times higher than what would be expected among men in the United States of similar ages.  However, the doctors cautioned, the existence of the increased number of A.L.S.-like cases should not create the same level of public alarm as the cognitive effects of brain trauma, which affect hundreds of former professionals and perhaps thousands of boys and girls across many youth sports.  Recent epidemiological studies have suggested that brain trauma in sports can be a risk factor for A.L.S.; for example, a 2005 paper found that Italian professional soccer players had developed the disease at rates about six times higher than normal. Studies have also linked service in the United States military to higher risk for A.L.S., possibly because of battlefield collisions and blast injuries.  The study, to be published Wednesday on the Web site of the Journal of Neuropathology & Experimental Neurology, represents the first firm pathological indications that brain trauma results in motor-neuron degeneration, and that the resulting disease (at least in the three men studied) is actually not A.L.S. It is a different disorder with different markings, specifically a pattern of two proteins in the spinal cord that compromise nerve function.  Dr. McKee had already found 12 deceased N.F.L. veterans to have had chronic traumatic encephalopathy, a progressive disease in brain tissue that results in cognitive impairment and eventually dementia. Two of those men — Wally Hilgenberg, a longtime linebacker for the Minnesota Vikings in the 1970s, and Eric Scoggins, who played only three games at linebacker for the 1982 San Francisco 49ers — also had A.L.S. diagnosed by their physicians.  When Dr. McKee examined the spinal-cord tissue of those men, as well as a former boxer who had A.L.S.-like symptoms, she found dramatically high levels of tau and TDP-43, two proteins known to cause motor-neuron degeneration. She said that they would appear in the cord as a result of blows to the brain, with the proteins probably traveling down the spinal cord, rather than direct injury to the spinal cord itself.
A study suggests that head trauma can cause degenerative diseases similar to A.L.S. and that Lou Gehrig may not have had Lou Gehrigâs disease.