Autonomic variability, depression and the disability paradox in spinal cord injury

Abstract

Study design: Longitudinal. Objective: With an increased risk of depression in spinal cord injury, the study longitudinally examines depression to understand how post-injury autonomic regulation and coping might be related to somatic and cognitive manifestations of depression after 3 years. Setting: Indian Spinal Injuries Center. Methods: Twenty-eight spinal cord injury participants completed the follow-up assessment of the Patient Health Questionnaire 3 years post-injury. The participants were grouped based on post-injury autonomic regulation (high and low HRV) and the somatic and cognitive manifestation of depression reflected in a depression ratio. Wilcoxson signed-rank test tested the post-injury (T1) and 3 year follow–up (T2) depression scores. Results: Depression score reduced after 3 years of injury (p ≤ 0.05). Only the high HRV group showed a higher depression ratio (somatic/ cognitive) atfollow-up (T2) (p ≤ 0.05). No difference was observed in post-injury coping between high and low HRV groups. Conclusion: The reduced depression score at follow-up (T2) aligns with the ‘disability paradox’ and mightindicate cognitive adaptation, specifically for those who showed autonomic adaptability in the form of post-injury high autonomic variability.