Incremental Effects of Subsequent Concussions on Cognitive Symptoms in the Sport Concussion Assessment Tool.

Objective: Patients who are fully recovered from a concussion may still be more vulnerable in the face of subsequent concussions. This study examines symptoms associated with repeated concussions in young and otherwise healthy adults.
Design: Cross sectional.
Setting: Institutional study at a university setting.
Participants: University students with a history of concussion.
Independent Variables: Participants were grouped based on numbers of concussions.
Main Outcome Measures: The impact of incremental concussion on symptom clusters in Sport Concussion Assessment Tools 5 and Spearman ranking correlation coefficients between symptom clusters.
Results: One hundred thirty-five participants reported having had 1 concussion, 63 reported 2 concussions, 50 reported 3 concussions, and 43 reported 4 to 6 concussions. Total severity scores over the range of concussion number (1, 2, 3, and greater than 3) did not show a clear incremental effect. However, average scores of cognitive symptoms rose with each subsequent concussion ( P ≤ 0.05). The largest incremental effect observed was that of second concussions on emotional symptom scores (t = 5.85, P < 0.01). Symptoms in the emotional and cognitive clusters were the most correlated regardless of the number of reported concussions; the correlations were lowest with symptoms associated with sensitivity to light or noise.
Conclusions: The incremental rise of cognitive symptom scores with each concussion affirms the importance of cognitive impairment in concussion assessment and implies a cumulative brain vulnerability that persists even after symptom resolution. The cognitive-emotional symptom clusters may reflect underlying concussion-induced impairments in the corticostriatothalamocortical (CSTC) networks, although sensitivity symptoms are potentially attributable to different neural correlates.
Competing Interests: The authors report no conflicts of interest.
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