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|Title:||PREDICTORS OF RESPONSE TO DEEP BRAIN STIMULATION FOR TREATMENT RESISTANT DEPRESSION|
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|Authors/Affiliations:||2 Sidney Kennedy; 2 Peter Giacobbe; 2 Jakub Konarski; 2 Sakina Rizvi*; 1 Helen Mayberg; 2 Andres Lozano; |
1 Emory University, Toronto, ON, Canada; 2 University Health Network, Atlanta, USA
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|Content:||Objective: Deep Brain Stimulation (DBS) to Brodmann Area 25 (BA25) is being investigated as a neurosurgical intervention for treatment-resistant depression (TRD). The purpose of this analysis is to explore putative predictors of response status 6 months after DBS. Based on the literature, we examined demographic, clinical and neuroanatomical variables as a priori candidates.|
Materials and Methods: Twenty subjects meeting DSM-IV-TR criteria for Major Depressive Disorder (MDD) received DBS to BA25. All subjects were followed on a monthly basis for a minimum of six months. Baseline demographic (age, sex), illness variables (baseline HDRS-17 score, duration of current depressive episode, number of previous depressive episodes), in addition to pre-operative MRI regional gray matter densities, were evaluated to determine their association with outcome status at 6-months post-DBS implantation.
Results: At 6-months, 12 of the 20 subjects (60%) met criteria for response (defined as > 50% reduction in the total HDRS-17 score from pre-surgery baseline), of whom seven (35%) were remitters (HDRS-17 < 7). Baseline demographic and clinical variables did not predict differences between groups either in terms of response or remission. There was a significant difference, however, between the responder/non-responder and remitter/non-remitter groups in gray matter density in the right posterior hippocampus, and bilaterally in the orbitofrontal cortices (OFC)-BA11. Decreased baseline right hippocampal gray matter density was associated with non-response, non-remission and also with increased duration of the current episode of depression. Similarly, decreased baseline bilateral OFC gray matter density was associated with non-response. Episode duration was not associated with OFC gray matter density.
A secondary analysis was performed to examine the relationship between responder status after 1 month of DBS and subsequent response and remission status at 6 months. There were 7 responders at 1 month, six of whom (85.7%) maintained their response at 6 months. Of the remaining 13 non-responders at 1-month, 6 (46.2%) met response criteria at 6 months. Responders at 1 month were significantly more likely to meet criteria for remission at 6 months compared to non-responders at 1 month.
Conclusion: Two baseline predictors of outcome following 6 months of DBS to BA25 were identified. Preoperative gray matter density in the right hippocampus and OFC bilaterally were significantly greater in responders and remitters at 6 months. Achieving response after 1 month of DBS was also significantly associated with remission status at 6 months. Baseline demographic and illness characteristics did not predict response or remission. These conclusions are limited by the small sample size and require replication in expanded and independent samples.
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