Reduced Superoxide Dismutase Levels Correlate with Severity and CV Risk in Sleep Apnea: Study

While obstructive sleep apnea is a major health concern in India, and previous research suggests that intermittent hypoxia generates reactive oxygen species that damage proteins and lipids, there remains a notable clinical gap regarding how these biomarkers correlate with disease severity in the Indian population. To address this, Dr. Kavitha Venkatnarayan and her team from St. John’s Medical College in Bengaluru aimed to investigate the levels of three specific oxidative stress markers in treatment-naive patients to better understand their relationship with polysomnographic parameters.

Therefore, the clinical investigation, conducted between June 2022 and June 2023 at a tertiary care facility, utilized Level I polysomnography to analyze sixty newly diagnosed patients—stratified into cohorts of twenty representing mild, moderate, and severe cases based on their apnea-hypopnea index (AHI)—and twenty healthy nonsmokers who served as controls. The researchers excluded any subjects previously treated with positive airway pressure therapy or those with comorbidities prone to causing hypoxia, focusing their primary and secondary analysis on the serum concentrations of SOD, thiobarbituric acid reactive substances (TBARS), and 8-hydroxy guanosine (8-OHdG) to evaluate antioxidant reserve and oxidative damage.

Key Clinical Findings of the study Include:

• Diminished Antioxidant Reserve: The study found that median serum SOD concentrations were significantly lower in individuals with sleep apnea at 31.42 ng/mL compared to 41.96 ng/mL in the healthy control group (p = 0.004).

• Severity-Linked Depletion: The study highlighted a significant decrease in SOD levels as the condition worsened (p = 0.001), showing a weak negative correlation with both the AHI (𝜌 = –0.295) and the supine respiratory index (𝜌 = –0.261).

• Unexpected Peroxidation Trends: The study noted that median TBARS levels were surprisingly lower in the patient group at 18.65 ng/mL compared to 51.06 ng/mL in controls (p = 0.005), which may have been influenced by specific sample processing factors.

• Stable Genomic Markers: The study reported that 8-OHdG levels showed no significant difference between the clinical cases and the control subjects (p = 0.237), potentially because the duration of intermittent hypoxia was insufficient to trigger measurable DNA oxidation.

The results suggest that the antioxidant reserve, specifically superoxide dismutase, is significantly compromised in patients with obstructive sleep apnea and that this reduction is directly proportional to the severity of the sleep disorder.

These findings suggest that clinicians might consider the evaluation of oxidative stress markers as a way to potentially assess the underlying physiological strain and associated cardiovascular risks in patients with disordered breathing.

Although the investigation was limited by its small, single-center sample size and the lack of matched controls, it emphasizes the clinical necessity for future research with larger populations to validate the utility of these biomarkers in predicting the systemic consequences of sleep apnea.

Reference

Nagaraju K, Venkatnarayan K, Veluthat C, et al. Evaluation of Oxidative Stress Biomarkers and Their Correlation with Severity of Obstructive Sleep Apnea. Indian J Sleep Med 2025;20(2): 48–51.