To establish population-based normative scores for post-concussion symptoms using validated assessment tools in an inclusive adult cohort.

Traumatic brain injuries are a major cause of disability worldwide. Repetitive mild TBIs (mTBIs) are associated with an increased risk of neurodegeneration. Assessing the severity of post-concussion symptoms and anticipating their long-term impacts remain challenging. Existing diagnostic/prognostic questionnaires have been validated primarily in male-dominated cohorts predominantly comprising athletes/veterans, hence constraining their applicability to the general population. Sex and gender are often confounded in the TBI literature.

The ComAction Initiative, a French-Canadian population-based observational study, included 405 adult participants who self-reported as female (63%), male (36%) or other gender (1%). Participants were split between healthy controls (n=142) and those that suffered a mTBI over six months ago (n=263). Data was collected using online questionnaires based on validated tools like the SCAT-5 and SF-36 scales. 

Using a test-retest approach, we confirmed the reliability (p<0.0001) of the SCAT-5 and SF-36 scores over 10-day (n=209, ρs=0.57) and 6-month (n=134, ρs=0.58) intervals. Normative scores were then established for the control and mTBI groups. Unsurprisingly, mTBI led to higher symptoms and severity scores. Interestingly, the number of subjective mTBIs correlated with symptom severity scores (between all subgroups from 0 to ≥3 mTBIs, p<0.05), while the number of diagnosed mTBIs did not (p=0.37). In the TBI group, no difference in SCAT-5 severity scores was observed initially when stratifying by sex or gender. However, combining the two variables resulted in a significant difference among participants that self-reported a masculine gender depending on their sex (male vs female, p=0.002). A similar trend was observed among participants assigned female at birth depending on their gender (cisgender vs transgender, p=0.054).

Establishing inclusive population-based normative scores can improve the assessment of post-concussion symptoms in the general population and the understanding of gender’s impact on recovery.