Abstract
BACKGROUND: Previous research has shown that Major Depressive Disorder (MDD) is accompanied by severe impairments in cognitive and autonomic processes, which may linger even when mood symptoms recover. This study aimed to analyse the relationship between depression severity, as measured by the Hamilton Depression Rating Scale (HAM-D), and how it affects heart rate variability (HRV) and cognitive function in patients with Major Depressive Disorder (MDD). METHODOLOGY: The cross-sectional study was conducted at RUHS College of Medical Sciences and Associated Hospitals, Jaipur, from July 2022 to January 2023 on 90 subjects having major depressive disorder (MDD) of either sex in the 20-40 age group using the Hamilton score for depression (HAM D), Heart Rate Variability (HRV) measurements, and a battery of cognitive tests. Regression analyses were conducted to examine the associations between HAM-D scores with both HRV parameters and cognitive functions. RESULTS: Results indicated a significant negative correlation between HAM-D scores and HRV measures with p<0.001, suggesting that increased depression severity is associated with reduced HRV. Additionally, higher HAM-D scores predicted poorer performance on cognitive tasks, particularly in the domains of executive function and working memory. The coefficient of determination r2=0.724 suggests that approximately 72.4% of the variance in the dependent variable (Hamilton rating score for depression) could be explained by the combined cognitive function and heart rate variability parameters. CONCLUSION: These findings highlight the potential utility of, emphasizing the importance of comprehensive assessment and treatment approaches that address both the affective and cognitive aspects of depression.