Objective: To prospectively examine recovery of cognitive function within one month following subconcussive sports related head trauma.
Design: A prospective study of New York State licensed professional boxers who underwent testing of cognitive functioning before and after (within days, one week, and one month) a professional bout.
Setting: Male professional athletes recruited from the New York State Athletic Commission and local boxing gyms.
Participants: Twenty-six licensed professional boxers were enrolled in the protocol. Data is presented on the 18 participants who completed testing on at least three of the four time points.
Interventions: Serial neuropsychological assessment before and after the athletes engaged in competition.
Main outcome measures: Neuropsychological measures of cognitive functioning, including new learning and memory, information processing speed, and mental flexibility.
Results: A series of repeated measures MANOVAS revealed significant within subject differences across testing on complex information processing and verbal fluency. Post hoc analyses indicated significant differences between time 1 (baseline) and time 4 (one month post), with scores one month following the bout indicating significantly improved performance. Memory scores did not change significantly across testing; however, prior boxing exposure measured by total number of professional bouts was associated with poorer memory performance.
Conclusions: Cognitive testing one month following participation in a professional boxing bout yielded scores suggestive of recovery to a level above the baseline. We conclude that baseline assessment taken during periods of intense training are likely confounded by other pre-bout conditions (i.e., sparring, rapid weight loss, pre-bout anxiety) and do not represent true baseline abilities. Instability of performance associated with mild head injury may complicate the interpretation of post-injury assessments. Practice effects may also confound the interpretation of serial assessments, leading to underestimation of the effects of sports related head trauma. Poorer cognitive performance was evident during the presumed recovery period in boxers with greater exposure to the sport (>12 professional bouts). This finding is consistent with reports of a cumulative effect of repetitive head trauma and the subsequent development of chronic traumatic brain injury. These data have implications for assessing recovery of function following head injury in players of other contact sports as well as determination of return-to-play following an injury.