Autonomic Dysregulation And Low Heart Rate Variability In Spinal Cord Injury (SCI): A Marker For Depression

ABSTRACT

Background: Spinal cord injury (SCI) results in physical, autonomic, and psychological consequences. Depression is among one the most common psychological effects of SCI, with an incidence of 22%. Depression is associated with reduced heart rate variability (HRV), but it remains unclear if autonomic dysregulation possesses depression risk in SCI. Thus, this study aims to explore the association between HRV and depression in SCI. Methodology: Ninety-one spinal cord injured patients (eighty-eight males and three female) representing three levels of severity of injury (cervical, high thoracic, and low thoracic) were recruited. Basal/resting HRV was assessed using 1000Hz Polar Heart rate monitor RS800 CX and Kubios HRV software. PHQ-9 assessed the depression; a cut of 10 was used to divide the sample into patients with probable Major Depressive Disorder (MDD) and non-MDD. Results: Non-parametric tests for between-group comparisons showed a significant difference in HRV variables (p<0.05) between the probable MDD and non-MDD SCI. Significant differences in HRV were observed between the low and high thoracic (p<0.05) and low thoracic and cervical group (p<0.05), suggesting that the functioning of the autonomic nervous system might differ with level of SCI. Conclusion: Depression in SCI has been associated with injury-related factors; we use the neurovisceral theory to explain the role of the autonomic nervous system in depression in SCI.