Recurrent Sport-Related Concussions Linked to Clinical Depression

Currently, an estimated 5.3 million Americans, (just over 2 percent of the U.S. population) live with disabilities resulting from traumatic brain injury (TBI), according to the Brain Injury Association of America. The Centers for Disease Control (CDC) has recently stated that concussions in sports have reached epidemic proportions in the United States. There are approximately 1.2 million participants in organized football annually in the U.S., and it is estimated that between 10 to 20 percent may sustain concussions every year. Football injuries associated with the brain occur at a rate of one in every 3.5 games. A new study, "Recurrent Sport-Related Concussion Linked to Clinical Depression," highlighting the negative effect of multiple mild traumatic brain injuries (MTBI), will be presented during the 71st Annual Meeting of the American Association of Neurological Surgeons (AANS) in San Diego.

The study will be presented by Julian Bailes, MD; Kevin Guskiewicz, PhD; and Stephen Marshall, PhD, on Monday, April 28, from 3:45 to 4 p.m. The effects of MTBI have both severe and long-term consequences for an individual. Neurological consequences of mild traumatic brain injuries are investigated by this study.

As a basis for the study, researchers reviewed a 2001 general health questionnaire, designed and analyzed by The Center for the Study of Retired Athletes. The questionnaire was completed by 2,488 retired National Football League players, with a 70 percent return rate. The age of respondents was 24-95 years, with an average age of 58 years.

The questionnaire results revealed that respondents: played pro football for 6.7 years (+/- 3.5 years) and played organized football for 15.1 years (+/- 4.2 years). Loss of consciousness (LOC) at least once during their NFL careers was reported by 54 percent. At least one concussion resulting in more than four weeks of symptoms during their NFL careers was reported by 9 percent. This report was then analyzed for MTBI statistical trends and subsequent neurological condition.

"The purpose of the study was two-fold," said Julian Bailes, MD, a co-author of the study and AANS member. "First, we wanted to find out if there was a significant relationship between concussion history and depression, and second, whether recurrent concussions predisposed players to Alzheimer's disease."

The analysis indicated that 61 percent of the former players sustained at least one concussion during their professional career, and 24 percent sustained a total of three or more concussions. An estimated 12 percent of respondents sustained five or more concussions, and 71 percent have returned to play on the same day as their concussion. The average number of concussions during an NFL football career is an estimated 2.1.

Although recurrent concussion has been previously considered a potential factor contributing to Alzheimer's disease, the results of the study did not reveal a significant association between concussion history (due to football) and Alzheimer's disease.

However, the results that 263 retired players (11 percent) had been diagnosed with clinical depression revealed there was an association between concussion history and depression. An estimated 87 percent of these players still suffer from depression, and 46 percent are currently being treated with antidepressant medications. An estimated 64 percent reported that depression does in fact limit their daily activities.

"The findings significantly underscore the importance of understanding and evaluating the potential neurological consequences of recurrent mild traumatic brain injuries," said Dr. Bailes. "Not only do concussions and other head injuries in early adulthood significantly raise the risk of depression decades later, but concussions are reported to have a permanent effect on thinking and memory skills later in life."

The study also revealed that retired players with more than five previous concussions had nearly a threefold risk of incidence depression, and those with 3-4 previous concussions had a two-fold increase in episodes of depression, when compared to those retired players with no history of previous concussion. Nearly 14 percent of those aged 35-44 have had episodes of depression, and more than 12 percent of those aged 55-64 also have experienced episodes of depression.

The study reinforces the theory that depressive symptoms are associated with TBI and are linked to injury severity, as well as rate of lifelong recovery.

Founded in 1931 as the Harvey Cushing Society, the American Association of Neurological Surgeons (AANS) is a scientific and educational association with more than 6,500 members worldwide. The AANS is dedicated to advancing the specialty of neurological surgery in order to provide the highest quality of neurosurgical care to the public. All active members of the AANS are certified by the American Board of Neurological Surgery, the Royal College of Physicians and Surgeons (Neurosurgery) of Canada or the Mexican Council of Neurological Surgery, AC. Neurological surgery is the medical specialty concerned with the prevention, diagnosis, treatment and rehabilitation of disorders that affect the entire nervous system including the spinal column, spinal cord, brain and peripheral nerves.