Structure and Connectivity of Depressive Symptom Networks Corresponding to Early Treatment Response

Abstract

Background: There are suggestions that denser network connectivity (i.e., the strength of associations between individual symptoms) may be a prognostic indicator of poor treatment response in depression. We sought to examine this aspect of depressive symptom networks in the context of early responses to treatment in adolescents. Method: Routine psychiatric data were obtained for child/adolescent service users who underwent at least three treatment sessions in publically funded services in England between 2011 and 2015 (N=3,017, 78% female; mean age [SD] = 14.43 [1.75]). Treatment response was assessed using the Reliable Change Index. Network analysis was used to compare the depressive symptom structure and connectivity of sub-samples who, after three treatment sessions, had: 1) positively responded (n= 566), 2) not reliably changed (n=2,277), and 3) reliably deteriorated (n=174), using matched samples to control for baseline severity. Outcomes: Overall connectivity was significantly weaker for the positive treatment response group at baseline, however, this group saw the largest increase in connectivity over the course of treatment. With regards overall importance of specific symptoms within networks, fatigue was most central for the unchanged and deteriorated groups, whereas 'feeling sad' was more central for the improved group. Interpretation: This study demonstrates that adolescents who respond early to treatment for depression are characterised by symptom networks that are less densely connected initially, yet increase in connectivity over the course of treatment. This may be indicative of 'positive spirals' whereby improvement in one symptom triggers an improvement in another, thereby increasing symptom-symptom associations even as severity decreases. Funding Statement: The study was supported by the Wellcome Trust grant 204366/Z/16/Z. Declaration of Interests: Dr. McElroy has nothing to disclose. Ms Napoleone has nothing to disclose. Prof Wolpert has nothing to disclose. Dr Patalay has nothing to disclose. Ethics Approval Statement: The data used in this study are service user records and specific ethical permission was not required to conduct this analysis. Approval was granted by the review board of the institution that hosts the data, The Child Outcomes Research Consortium (CORC; https://www.corc.uk.net/), and all data management and confidentiality protocols governing the use of the dataset were followed.