Dr. Ann McKee of the Boston University School of Medicine discusses the impact of head trauma Tuesday in Tampa, Fla. (Chris O'Meara/Associated Press)

Young athletes who thrive on the rough and tumble of contact sports like hockey or football could be putting their long-term cognitive health at risk if they suffer even one concussion, researchers suggest.

In a study of former university athletes now in their 50s and 60s, Montreal researchers found a noticeable decline in some of their mental processes and motor function — 30 years after the men had experienced concussion — compared to former athletes who hadn't sustained the brain injury.

"This study shows that the effects of sports concussions in early adulthood persist beyond 30 years post-concussion and that it can cause cognitive and motor function alterations as the athletes age," said Louis De Beaumont, a graduate student in neuropsychology who led the University of Montreal study.

"In the light of these findings, athletes should be better informed about the cumulative and persistent effects of sports concussion on mental and physical processes so that they know about the risks associated with returning to their sport."

A concussion is a traumatic injury to the brain that results from a violent blow, shaking or spinning. Symptoms include confusion, loss of memory, headache, dizziness and sometimes loss of consciousness. Concussion is primarily treated with rest until symptoms disappear, and may require that an athlete not return to play for a specific period to prevent further brain injury from another blow to the head.

The study compared 19 former athletes who had sustained concussion while playing sports at universities across Canada three decades ago with 21 similarly aged former athletes with no history of concussion. All participants were healthy and continued to engage in regular physical activity at least three times a week.

Researchers gave the men a number of tests to assess memory, language and the ability to follow simple verbal and written commands, as well as physiological tests. Those who had sustained concussion earlier in life showed some definite, though subtle, differences in some test results.

De Beaumont said subjects who had been concussed only once or twice in their early adulthood showed a decline in their attention and memory and a slowing of some of their movements compared to athletes who had not had the brain-rattling injuries.

The study, published online Wednesday in the journal Brain, did not analyze whether subjects who had sustained a greater number of concussions had greater cognitive deficits than those who had fewer concussions.

'Exacerbated by the aging process'

De Beaumont said the type of impairments found in study participants who suffered concussion while playing sports as young men aren't seen in young athletes in general — "and that's the important part in this study, that it was specific to former athletes with concussions."

"Young athletes don't show any kind of memory impairments or executive function impairments," he said Tuesday from Montreal. "This is why we call it cognitive decline exacerbated by the aging process."

However, he stressed that the men maintained active lives, functioned well and showed no signs of Alzheimer's or Parkinson's disease.

Whether the decline in brain function exhibited is a precursor to Alzheimer's disease or other forms of dementia, that "isn't an assumption that we can make," he said. "But we're running a followup study on these athletes that's going to try and assess exactly that question."

"Are these cognitive declines seen at 60 years old still present or are they even more exacerbated as they get older and do they have patterns of Alzheimer's disease when they get to 70 years old, for instance?"

Calling it a "nice, neat study," brain injury researcher Paul Comper said the Montreal paper provides scientific evidence to support what's been anecdotally suspected for a long time: "Avoid these head injuries because you never know what's going to happen 20 or 30 years down the road.

"It lends support to the growing body of evidence that these kind of injuries need to be taken seriously, that there are potential future implications, for even a single concussion," said Comper, a neuropsychologist at Toronto Rehab.

"The bottom line is that neurological health and safety needs to be paramount in both amateur and professional sports."

'Need to identify and rest concussions'

In a related development Tuesday, brain-injury experts at the Boston University School of Medicine reported that former Tampa Bay Buccaneer Tom McHale had chronic traumatic encephalopathy (CTE), a degenerative brain disease caused by head trauma, when he died last year of a drug overdose at age 45.

McHale is the sixth former NFL player since 2002 to be diagnosed post-mortem with CTE, a condition that progresses to full-blown dementia.

The doctors, members of Boston University's Center for the Study of Traumatic Encephalopathy, also discovered early evidence of CTE in a recently deceased 18-year-old boy who suffered multiple concussions playing high school football.

The discovery of CTE in the youth, who was not identified at the family's request, should act as a red flag about the dangers of sports-related concussion, Boston neurosurgeon Dr. Robert Cantu said in a release.

"Our efforts to educate athletes, coaches and parents on the need to identify and rest concussions have only been moderately successful because people have been willing to look the other way when a child suffers a concussion," he said. "I hope the discovery of CTE in a child creates the urgency this issue needs."