Network analysis of depressive symptoms and vital exhaustion in patients with acute coronary syndrome

Abstract

Background There is controversy in the literature over the relationship between depression and vital exhaustion, which is characterised by feelings of fatigue, but without characteristic low mood. Recently, it has been argued that psychopathological symptoms are better reflected as a network, rather than indicative of latent traits. In this approach, co-morbidity or relationships among different traits are hypothesised to arise from the direct associations among multiple, potentially overlapping, conditions. We therefore analysed symptoms of depression and vital exhaustion to determine the interrelationships among these symptoms. Methods 408 patients with acute coronary syndrome (ACS) completed questionnaires on depression and vital exhaustion. Items were subjected to network analysis using multidimensional scaling in Stata, using all items (n=23) in the first network, and a second network using only items that best reflected 14 unique symptoms. Results Both analyses showed a single network, indicating no evidence for separation of depressive and exhaustion symptoms, with 20 and 17 bridges respectively. The networks had low reciprocity (0.086 and 0.103 respectively), however, which indicated for example that ‘feeling slowed’ was a result of having other depressive symptoms, but not vice versa. Conclusions There was no evidence for a separation of depressive and exhaustion symptoms. Findings instead showed that certain depressive symptoms are more likely to be as a result of having others. Network analysis can provide unique insights into the interrelationships among psychological variables, and provides an avenue for theory testing and development.