An Exploration of Sex- and Hormone-Related Differences in Cognitive-Motor Performance, Brain Network Integrity, and Recovery Metrics Following Concussion

Concussion, a form of mild traumatic brain injury, presents itself differently in all who sustain them. This makes diagnosis, recovery tracking, and return to play decisions extremely difficult. Along with general individual differences, sex and sex hormones may have an impact on incidence, symptoms, and time to recovery. The purpose of these dissertation projects was to better understand the general effects of concussion and add to the literature informing clinicians of what to look for following injury. Within this, another focus was to explore the potential impact of aspects related to sex on current metrics for examining concussive injury. Data was collected from varsity level university athletes with and without a previous history of concussion. Data included visuomotor performance on a standard and non-standard reaching task, sport concussion assessment tool measures including symptom scales and balance, resting state functional magnetic resonance imaging, and hormone levels (estradiol, testosterone, and progesterone) via salivary enzyme immunoassays. Results from the three studies add to the literature surrounding both individualized and sex-related differences in outcomes following concussion, as well as the impact of hormones on general visuomotor performance and resting state functional connectivity (rs-FC) in females. Sex-specific differences were noted in visuomotor performance and symptom presentation. Progesterone and testosterone both exhibited positive relationships with visuomotor performance, and progesterone also exhibited a positive relationship with rs-FC in the dorsal attention network and a negative relationship with rs-FC in the salience ventral attention network. Overall, these results provide more detailed insight into the heterogeneous nature of concussion, and support that it is important to consider individuality in all cases of return to play decisions.