In adults with major depressive disorder (MDD), effective treatment has been associated with increases in both heart rate variability (HRV) and cortical thickness. However, the impact of treatment on these indices has not yet been examined in adolescents. Cortical thickness and HRV were measured in twelve adolescents with MDD before and after 8 weeks of treatment with a selective serotonin reuptake inhibitor (SSRI). We examined treatment-related changes in depression symptoms, HRV, heart rate (HR), and cortical thickness, and analyzed correlations among these change indices. At follow-up, patients showed significantly decreased depression severity, increased HRV and increased thickness of the left medial orbitofrontal cortex (OFC). Clinical improvement was associated with increased HRV and decreased HR. Increased HRV was associated with increased cortical thickness of left lateral OFC and superior frontal cortex. Due to the small sample size, results represent preliminary findings that need replication. Further, in the absence of a placebo arm, we cannot confirm that the observed effects are due solely to medication. These preliminary findings suggest that SSRI treatment in adolescents impacts both cortical thickness and autonomic functioning. Confirmation of these findings would support OFC thickness and HRV as neurobiological mediators of treatment outcome.
Bibliographical noteFunding Information:
The authors would like to first and foremost thank the adolescents and families that contributed to this study. The study was funded by grants to Dr. Cullen including the National Institute of Mental Health ( K23MH090421 ), the National Alliance for Research on Schizophrenia and Depression, the University of Minnesota Graduate School, and the Minnesota Medical Foundation. Dr. Koenig is supported by a Physician-Scientist-Fellowship provided by the Medical School, University of Heidelberg, Germany, and acknowledges the financial support through a Post-Doctoral Scholarship provided by the Daimler and Benz Foundation (Ladenburg, Germany) and the Thrasher Research Fund Early Career Award provided by the Thrasher Research Fund (Salt Lake City, UT, USA). These resources supported the roles of design and conduct of the study; collection, management, and analysis of the data; and interpretation of results and preparation of the publication. We thank Michael Gaebler for his helpful support regarding the Siemens PPG data format and readout.
- Cortical thickness
- Heart rate
- Heart rate variability