CHICAGO (AP) Football players with memory and behaviour problems have no way of knowing for sure if getting hit too many times caused brain damage. The only test to diagnose their condition is done after death in an autopsy.

But now, researchers are experimenting with an imaging technique to detect a debilitating condition caused by repeated concussions. And a study in Boston of five retired athletes three National Football League players, a boxer and a wrestler is being called a preliminary first step toward diagnosis and maybe even treatment. The imaging found suspicious chemical changes in the former athletes’ brains. They’d suffered multiple hits to the head during play and showed behaviour symptoms indicating possible brain damage. The chemical changes were not found in five healthy study participants. The results from this noninvasive “virtual biopsy” technique suggest that the athletes had chronic traumatic encephalopathy, the study authors said. The disease is a suspected cause of “punch-drunk” symptoms, memory lapses and behavior changes in NFL players and others who have had repeated concussions.

The issue has gained scrutiny since autopsies found brain degeneration in a handful of former NFL players who died young. Concerns about the dangers of repeated concussions have led to congressional hearings, policy recommendations from doctor groups and restrictions on how soon professional and student athletes can return to play after being hit in the head. The study was presented yesterday at the Radiological Society of North America’s annual meeting in Chicago.