Concussion, Cognition, and the Hippocampi in Collegiate Football Players

May 13, 2014

Concussion, Cognition, and the Hippocampi in Collegiate Football Players

  1. Brandy R. Matthews, MD

Left hippocampal volumes and reaction times correlated with clinician-diagnosed concussion.

  1. Brandy R. Matthews, MD

Accumulating evidence suggests that a history of concussion in young athletes may be associated with changes in cognitive and behavioral performance and with structural and functional changes in the brain as revealed through various neuroimaging techniques. In this cross-sectional investigation, 50 college football players (25 with concussion, 25 without concussion) self-reported their years of organized tackle football experience and the number of clinician-diagnosed concussions during that time period. Before starting Division I college football, players completed a battery of standardized cognitive and behavioral testing summarized as composite measures of verbal memory, visual memory, reaction time, and impulsivity. Investigators performed 3T brain magnetic resonance imaging of the players and 25 age-matched controls with no history of head injury, using FreeSurfer software to assess hippocampal volumes.

Compared with healthy controls, collegiate football athletes had smaller bilateral hippocampal volumes; the correlation was strongest in players with histories of concussion. Left, but not right, hippocampal volumes correlated with the number of years playing football (range, 9–14 years) but not with clinician-diagnosed concussions (15 players with 1–2 concussions; 10 players with 3–5). Reaction time, but not other cognitive or behavioral assessments, demonstrated a similar inverse correlation with years played.


As the study authors acknowledge, these results are affected by the cross-sectional study design and the bias introduced by self-report. Likewise, variability in clinician threshold for diagnosing concussion in numerous settings over time represents an important confounder. The sample size is small, but the study was adequately powered to detect a specified difference, with appropriate statistical adjustment for multiple comparisons. Although the study design does not allow causality to be established, the objective anatomical (left hippocampus) and clinical (reaction time) differences correlated with years of exposure to playing tackle football, adding to the growing body of knowledge that subconcussive hits may be an important contributor to the risk associated with contact sports in young athletes.

Editor Disclosures at Time of Publication

  • Disclosures for Brandy R. Matthews, MD at time of publication Grant / Research support National Institute on Aging


Reader Comments (2)

MARVIN ZIMMERMAN Physician, Internal Medicine, retired

I like the format and clear evaluations

HARVEY CANTOR Glennon Childrens' Hospital

I wonder how long, if ev er, it will take our 'Msn-Country' finally o come to the reality that contact sports 'are bad for the brain', AND to begin the process of informing parents and Educators of the cognitive risks to which we are subjecting our students?

Professor (Clinical) Pediatric Neurology
St. Louis University School of Medicine

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