Concussions in the NFL lead to Depression



Professional football players who suffer from a concussion are more likely to develop long-term mental health episodes such as depression.


The prevalence of concussions in football has significant mental health ramifications. One concussion occurs every 2.44 NFL games. A study published in the American Journal of Sports Medicine looked at correlations between concussion incidences and depression (Nine-Year Risk of Depression Diagnosis Increases With Increasing Self-Reported Concussions in Retired Professional Football Players, 2012. Zachary Y. Kerr, et al.).

The study used a 2001 General Health Survey sent to the 3,729 members of the NFL Retired Players Association. A second General Health Survey was sent nine years later in 2010. The surveys asked questions regarding the respondents physical and mental health as well as the number of concussions suffered during their professional careers. Those exhibiting depression in the first survey were not used in the study.

Of the players who reported never having a concussion, only 3.0% were diagnosed with depression. Of those who reported suffering from 10 or more concussions, 26.8% were found to suffer from depression. The relationship between number of self-reported concussions and likelihood of suffering from depression was a linear relationship. Those who reported suffering from 3 or more concussions were twice as likely to suffer from depression as those reporting 1-2 concussions over their career and three times more likely than retired professional football players who did not suffer any concussions over their professional career.

Work on depression in US soldiers in Iraq has suggested there may be a link between tauopathies, tau protein deposits in the brain, and depression. Repeated head impacts elevate tau protein levels causing neural breakdown. The physical blow to the head could directly cause neuron death or breakage of neuron connections. Lesions in neural tissue could release harmful biochemical agents.

Concussions often go unreported, especially at the amateur level. This study highlights the importance of monitoring the accumulation of concussions. Other studies have found that concussions can lead to negative personality and cognitive changes. Although the dangers of concussions cannot be underscored enough, with regards to this study on concussions in former NFL players there are several limitations. Most significantly, it is likely that there are many lurking variables that this study could not account for. For example, risky behavior that leads to concussions may be favored in those prone to depression. Career-ending concussion accumulation may lead to depression. Nonetheless, the number of concussions suffered is a significant predictor of depression later in life.

Most likely, a positive relationship between concussions and depression would apply across sports, competition levels as well as to the military and other non-athletic instances.

Exercise versus Anti-Depressant Medication

depressed girl

Exercise has been shown to be comparable in remission rate and adherence rate to anti-depressant medication. However, exercise does not have the social stigma that prevents many from seeking anti-depressant medication.


Mild to moderate major depressive disorder (MDD) is a serious illness that affects many Americans. According to the Global Burden of Disease, MDD ranks second globally, only behind heart disease, in responsibility for years of life lost due to disability or premature death. According to a 1999 report from the US Surgeon General, only 23% of people inflicted with MDD seek treatment. Unfortunately, the social stigma around depression, and psychological problems in general, prevents many people from seeking treatment. This stigma is a major hurdle to getting proven pharmaceutical anti-depressant treatments out to those who need them. A small, carefully controlled study found that exercise, an activity viewed positively by society, may work as well as anti-depressant pharmaceuticals and better than cognitive therapy in curing mild to moderate major depressive disorder (Exercise treatment for depression: Efficacy and dose response (2004)).

The study, published in 2005 in the American Journal of Preventive Medicine, divided study participants with MDD into 4 experimental groups and a control group. The experimental group was separated by dosage of exercise and frequency by which that dosage was administered. The exercise dosages were the public health recommended 17.5 Cal/kg/week and a low dosage of exercise at 7.0 Cal/kg/week. The frequency by which these dosages were administered was 3 times a week and 5 times a week. The control group participated in flexibility exercise 3 days a week.

Interestingly, the frequency of exercise per a week did not affect the success of the treatment. However, dosage of exercise did.  Although the public health recommended dosage of 17.5 Cal/kg/week had a success rate (47% reduction in 17-item Hamilton Rating Scale for Depression-HRSD) comparable to pharmaceutical anti-depressants, the low exercise dosage of 7.0 Cal/kg/week resulted in a success rate (30% HRSD reduction) only slightly better than the placebo (29% HRSD reduction). The results of the different dosages are shown in the figure below.

The study administered exercise dosage in a clinically controlled, individual setting to ensure validity of dosage and exclude social benefits of exercising with others. The treatments were administered for 12 weeks.

Remission rate of depression symptoms by the public health recommended exercise dose was 42%. This compares to a 42% remission rate of anti-depressant medication imipramine hydrochloride and a 36% rate of remission for cognitive behavioral therapy (R.R. Pate, M. Pratt, S.N. Blair et al. Physical activity and public health. 1995). In addition, exercise treatment has been criticized for treatment adherence. However, in this study the exercise treatment adherence (72%) compares favorably to adherence rates found in medication trials.

In summary, the public health recommended dosage of exercise treats depression as well as anti-depressant medication. However, low dosage of exercise did little better than the placebo control group. Frequency did not affect the results. Adherence rate was comparable to medication trials suggesting it could provide a viable, stigma-free alternate treatment. This study was small by many standards, 80 participants, but more research should be done to explore the alternate treatment of mild or moderate major depression disorder with exercise.