performance. The interaction of LD and concussion history was not
significant (F=1.17; P=.28). A follow-up series of univariate F tests
was completed to identify the specific neuropsychological measures
that accounted for the significant MANOVA. Tests for the LD main
effect were Trails B (F=15.98;P*.001); SDMT (F=22.9; P*.001);
COWAT (F=11.6; P*.001); and Hopkins delayed memory (F=11.8;
P*.001). For the history of concussion main effect, significant tests
included Trails B (F=6.1; P=.002); SDMT (F=7.8; P*.001); and total
symptoms reported (F=4.6; P=.01).
To evaluate concussion group differences on the neuropsychological
tests, additional post hoc analyses were conducted using the Tukey
Honest Significant Difference test for unequal subjects.24 Table 1
presents the group means (SDs) for athletes. The group with no
history of concussion reported fewer symptoms than both the single
concussion group (P=.04) and the multiple concussion group
(P*.001) on the concussion symptom inventory. Baseline symptoms
increased as the number of concussions increased. On Trails B, the
multiple concussion group performed significantly worse at baseline
than the group with no history of concussion (P=.02) and the single
concussion group (P*.001). Baseline data also differed significantly
on the SDMT with the multiple concussion group performing worse
than both the group with no history of concussion (P=.008) and the
single concussion group (P*.001). These findings are not attributed to
preexisting group differences in terms of aptitude as the multiple
concussion group had higher SAT and ACT scores than did the group
with no history of concussion and the single concussion group. The
table presents demographic and neuropsychological test data for the
group with LD and the group without LD.
To investigate the interplay between concussion history and LD on
baseline neuropsychological test performance, a concussion history
and LD interaction term was constructed. Univariate F tests for all 10
neuropsychological variables demonstrated statistically significant
interactions for Trails B (F=4.99; P=.007) and SDMT (F=4.74;
P=.009). In both cases, athletes with a history of multiple
concussions and LD performed significantly worse than did athletes
with no history of LD who had experienced multiple concussions
(Figure 1).
In-Season Concussions
Nineteen players in the study sample were diagnosed by team
medical staff as sustaining a concussion during the course of the
1997-1999 seasons. Thirteen individuals sustained a grade 1
concussion (mental status abnormalities resolved within 15 minutes),
4 athletes sustained a grade 2 concussion (mental status
abnormalities that lasted longer than 15 minutes, but resolved within
45 minutes), and 2 athletes sustained a grade 3 concussion (brief
[approximately 5-10 seconds] loss of consciousness). The time
between baseline testing and in-season c
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