@article{ref1,
title="Nine-year risk of depression diagnosis increases with increasing self-reported concussions in retired professional football players",
journal="American journal of sports medicine",
year="2012",
author="Kerr, Zachary Y. and Marshall, Stephen W. and Harding, Herndon P. and Guskiewicz, Kevin M.",
volume="40",
number="10",
pages="2206-2212",
abstract="BACKGROUND: Concussions may accelerate the progression to long-term mental health outcomes such as depression in athletes. <br><br>PURPOSE: To prospectively determine the effects of recurrent concussions on the clinical diagnosis of depression in a group of retired football players. STUDY DESIGN: Cohort study; Level of evidence, 2. <br><br>METHODS: Members of the National Football League Retired Players Association responded to a baseline General Health Survey (GHS) in 2001. They also completed a follow-up survey in 2010. Both surveys asked about demographic information, number of concussions sustained during their professional football career, physical/mental health, and prevalence of diagnosed medical conditions. A physical component summary (Short Form 36 Measurement Model for Functional Assessment of Health and Well-Being [SF-36 PCS]) was calculated from responses for physical health. The main exposure, the history of concussions during the professional playing career (self-report recalled in 2010), was stratified into 5 categories: 0 (referent), 1 to 2, 3 to 4, 5 to 9, and 10+ concussions. The main outcome was a clinical diagnosis of depression between the baseline and follow-up GHS. Classic tabular methods computed crude risk ratios. Binomial regression with a Poisson residual and robust variance estimation to stabilize the fitting algorithm estimated adjusted risk ratios. χ(2) analyses identified associations and trends between concussion history and the 9-year risk of a depression diagnosis. <br><br>RESULTS: Of the 1044 respondents with complete data from the baseline and follow-up GHS, 106 (10.2%) reported being clinically diagnosed as depressed between the baseline and follow-up GHS. Approximately 65% of all respondents self-reported sustaining at least 1 concussion during their professional careers. The 9-year risk of a depression diagnosis increased with an increasing number of self-reported concussions, ranging from 3.0% in the &quot;no concussions&quot; group to 26.8% in the &quot;10+&quot; group (linear trend: P <.001). A strong dose-response relationship was observed even after controlling for confounders (years retired from professional football and 2001 SF-36 PCS). Retired athletes with a depression diagnosis also had a lower SF-36 PCS before diagnosis. The association between concussions and depression was independent of the relationship between decreased physical health and depression. <br><br>CONCLUSION: Professional football players self-reporting concussions are at greater risk for having depressive episodes later in life compared with those retired players self-reporting no concussions.  Keywords: American football  <p /> <p>Language: en</p>",
language="en",
issn="0363-5465",
doi="10.1177/0363546512456193",
url="http://dx.doi.org/10.1177/0363546512456193"
}