Role of anxiety in exercise intolerance and autonomic nervous system dysfunction post-concussion.

OBJECTIVE

To compare autonomic nervous system (ANS) response using the Buffalo Concussion Bike Test (BCBT) between adult post-concussion patients with and without pre-existing and post-injury anxiety.

DESIGN

Cross-sectional cohort study of participants from the Targeted, Multidomain (T-MD) Treatment for Concussion Randomized Controlled Trial.

SETTING

Two concussion specialty clinics.

PARTICIPANTS

Ages 18-49 years, 8 days to 6 months from injury, without a history of cardiovascular/neurological/vestibular disorders. 256 participants were eligible, 120 declined, 136 enrolled, and 30 were excluded.

EXPOSURES: Participants completed the BCBT at a baseline study visit following initial clinical evaluation.

MAIN OUTCOMES AND MEASURES: Number of BCBT stages completed and Visual Analogue Scale (VAS), heart rate (HR), blood pressure (BP), and Ratings of Perceived Exertion (RPE) pre- and post-BCBT.

RESULTS

106 participants (age = 25.5 [12.5], 66 [62.3%] female) were included, 44 (41.5%) with pre-existing anxiety, 61 (57.6%) without pre-existing anxiety, 33 (31.1%) with post-injury anxiety, and 73 (68.9%) without post-injury anxiety. Eighteen (17.0%) were in both anxiety groups. Results supported a significant group x time interaction in participants with pre-existing anxiety for increased diastolic BP (F[1,97] = 5.03, p = 0.03) and VAS (F[1,99] = 5.05, p = 0.03) while controlling for covariates. Participants with pre-existing anxiety (median = 8[4]) and post-injury anxiety (median = 8[5]) completed fewer BCBT stages than those without pre-existing (median = 11[6], p < 0.01) and post-injury (median = 10[6], p = 0.03) anxiety.

CONCLUSIONS

Adults with pre-existing and post-injury anxiety experienced altered physiological responses to exercise post-concussion and completed fewer stages of the BCBT. Anxiety should be considered by clinicians when interpreting findings from exercise intolerance tests such as the BCBT.

TRIAL REGISTRATION: www.

CLINICALTRIALS: gov ; identifier: NCT04549532; https://clinicaltrials.gov/study/NCT04549532.