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Michael W.Collins, PhD Scott H. Grindel, MD Mark I Lovell, PhD Duane E. Dede, PhD David J. Moser, PhD Benjamin R. Phalin. BS Sally Nogle, MA. ATC |
Michael Wasik. MEd, ATC David Cordry, MA Michelle Klotz Daugherty, MA Samuel F. Sears, PhD Guy Nicolette, MD Peter Indelicato, MD Douglas B. McKeag, MD |
The management of mild tramatic brain injury (MTBI; eg, concussion, defined as a traumatically induced alteration in mental status not necessarily resulting in loss of consciousness) in athletics is currently one of the most compelling challenges in sports medicine. Despite the high prevalence and potentially serious outcomes associated with concussion systematic research on this topic is lacking. Many sports medicine practitioners are not satisfied with current return to play and treatment options, which do not appear to be evidence based.
Context Despite the high prevalence and potentially serious outcomes associated with concussion in athletes, there is little systematic research examining risk factors and short and longterm outcomes. Objectives to assess the relationship between concussion history and learning disability (LD) and the association of these variables with neuropsychological performance and to evaluate postconcussion recovery in a sample of college football players.
Design, Setting, and Participants A total of 393 athletes from 4 university
football programs across the United States received preseason baseline evaluations
between May 1997 and February 1999. Subjects who had subsequent football related
acute concussions (n = 16) underwent neuropsychological comparison with matched
control athletes from within the sample
(n = 10).
Main Outcome Measures Clinical interview, 8 neuropsychological measures, and concussion symptom scale ratings at baseline and after concussion.
Results Of the 393 players, 129 (34%) had experienced I previous concussion and 79 (20%) had experienced 2 or more concussions. Multivarlate analysis of variance yielded significant main effects for both LD (P<001) and concussion history (P =.009), resulting in lowered baseline neuropsychological performance. A significant interaction was found between LD and history of multiple concussions and LD on 2 neuropsychological measures (TraitMaking Test, Form 8 (P=.0071 and Symbol Digit Modalities Test [P =.0091), Indicating poorer performance for the group with LD and multiple concussions compared with other groups. A discriminant function analysis using neuropsychological testing of athletes 24 hours after acute inseason concussion compared with controls resulted in an overall 89.5% correct classification rate.
Conclusions Our study suggests that neuropsychological assessment is a useful indicator of cognitive functioning in athletes and that both history of multiple concussions and LD are associated with reduced cognitive performance. These variables may be detrimentally synergistic and should receive further study.
COMMENT
The results of this study suggest that history of concussion and LD are independently
related to lower baseline cognitive performance within a large, multiuniversity
sample of football players, the negative impact of LD on neurocognitive functioning
in a general population is well established. Within our sample, the domains
of executive functioning (ie, ability to plan and execute a nonverbal behavior),
speed of information processing, speeded word fluency, and memory appear to
be attenuated in those athletes with LD. We also found that a history of concussion
Is significantly and independentlv associated with longterm deficits in the
domains of executive functioning and speed of information processing, as well
as an increase in self reported symptoms. Such defects appear to be present
in those individuals who have sustained 2 or more prior concussions. In this
study, a history of 1 concussion does not appear to result in the longterm cognitive
morbidity associated with 2 or more episodes of concussion.
The study findings also suggest an interaction of prior concussion and LD on select neuropsychological measures. Players with a history of 2 or more concussions and LD performed significantly worse on tests of executive functioning (Trails B) and speed of Information processing (SDMT) relative to players with concussions who were not diagnosed with LD, suggesting an additive effect of LD and multiple episodes of concussion on lowered functioning. When compared with accepted normative values, athletes with LD and multiple concussions performed in the brain impairment range on these 2 measures.
Three potential hypotheses may account for these findings. First, athletes with LD who experienced concussion may have had less brain reserve capacity than athletes without LD. The margin of cognitive reserve may be less in athletes with LD and the threshold for manifesting neurobehavioral morbidity may be lower. A second hypothesis is that LD may have made the initial diagnosis of concussion more complex and confusing.