Recurrent sport-related concussion appears to be related to an increased risk of clinical depression in retired professional football players, according to new research published in the June issue of Medicine & Science in Sports & Exercise®, the official journal of the American College of Sports Medicine .

In the study, 2,552 retired professional football players (average age of 53; average professional career of six years) completed a general health questionnaire, including information about prior injuries and other markers for depression. A second questionnaire focusing on Mild Cognitive Impairment (MCI) related issues was completed by a subset of 758 retired professional football players (age 50 and older).

Of all respondents, 269 (11.1 percent) reported having prior or current diagnosis of clinical depression. There was an association between recurrent concussion and diagnosis of depression, suggesting the prevalence increases with increasing concussion history.

Compared to retired players without a history of concussion, retired players reporting three or more previous concussions were three times more likely to be diagnosed with depression; those with a history of one to two previous concussions (36.3 percent) were 1.5 times more likely to be diagnosed with depression. According to Kevin M. Guskiewicz, Ph.D., FACSM, lead author of the paper, these findings emphasize the importance of understanding potential neurological consequences of recurrent concussion.

"The more we study head injuries, the more we discover about their long-term consequences, particularly in impact sports where concussions are more prevalent," said Guskiewicz. "Depression can be as debilitating as a physical disease or disability that many retired athletes experience, so this is a call to action for athletes and the clinicians who manage their injuries to better educate themselves about not only the acute, but also the chronic effects of concussion."

The study was conducted through the Center for the Study of Retired Athletes at the University of North Carolina, Chapel Hill.

An author on the study, and renowned head injury expert, Robert C. Cantu, M.D., FACSM, says unfortunately, because there is no biologic, radiographic marker of concussion, though there has been an explosion of research on concussion and multiple national and international consensus conferences and statements, much still remains to be settled regarding athletic concussion diagnosis and management. Cantu will present a historical overview of concussion Friday, June 1, during the D.B. Dill Historical Lecture at ACSM's 54th Annual Meeting in New Orleans.

"There is a significant amount of controversy on issues of concussion," says Cantu. "One of the biggest problems is the fact there is no single marker for concussion. It relies on a clinical diagnosis, which is not simple. We are still answering questions, such as how many concussions are too many and what is the true incidence of mild cognitive impairment and concussion? Concussions are underreported by a factor of five to 10 times, especially in sports like football where athletes wear helmets so you cannot see their faces, athletes are often many yards away from medical observers, and play is not continuous. In such sports, it is possible for an athlete to play through most mild concussions."

It is estimated that roughly 85 percent of concussions go undiagnosed, and actual number of sports- and recreation-related concussion nationwide is nearly seven times the 300,000 that are officially diagnosed. ACSM has issued recommendations to help team physicians properly evaluate, diagnose and treat concussions.

Chris Nowinski, former all-Ivy Harvard football player and headliner WWE professional wrestler who ended his career due to head injuries, will support Cantu's presentation in an overview of his experience with concussion, Saturday, June 2, at the ACSM meeting.

The risk of concussion is most common and prevalent in impact-sports that require the use of helmets. These include, but are not limited to, football, ice and field hockey, soccer, lacrosse, softball and wrestling.

Experts suggest you look for some of these symptoms if a concussion is suspected.

-- Loss of consciousness
-- Confusion
-- Vacant stare
-- Slurred speech
-- Excessive drowsiness
-- Headache
-- Fatigue
-- Dizziness
-- Nausea/vomiting
-- Irritability

Cantu emphasizes the following points, often misunderstood in concussion treatment and management.

-- Loss of consciousness (LOC) is rarely present in sport concussion, and brief LOC does not correlate to severity of injury.
-- The type, severity and duration of symptoms are most useful in determining concussion severity.
-- The assessment and management of the concussed athlete must be individualized.
-- Factors that must be considered include age, sport and previous concussion history including proximity and severity.
-- Symptomatic athletes should not be allowed to return to play.
-- Neuropsychological testing may help in evaluating cognitive function and making return-to-play decisions.
-- Physical and mental rest appears important to recovery.
-- Younger athletes should be treated more conservatively.
-- Return to activity should be gradual and progressive.

The best way to prevent a concussion is to avoid trauma to the head. "Helmet use eliminates skull fracture, and significantly decreases major head trauma, but does not prevent concussion. By using the helmeted head improperly as a striking weapon, helmets may actually increase the incidence of concussion," says Cantu. Cantu adds it's important to know how to properly use helmet and ensure it fits properly.

The American College of Sports Medicine is the largest sports medicine and exercise science organization in the world. More than 20,000 international, national, and regional members are dedicated to advancing and integrating scientific research to provide educational and practical applications of exercise science and sports medicine.