PURPOSE: The purpose of this study is to identify neuroimaging, physiological, and clinical predictors of response, remission, and recovery to repetitive transcranial magnetic stimulation in youth with treatment resistant major depressive disorder.
BACKGROUND: Major depressive disorder (MDD) is a major public health problem in adolescents. Unfortunately, there are no effectively targeted treatment options for this age group. Current remedies are limited in their effectiveness in youth with response and remission rates no greater than 60 to 30% respectively and treatment effects are not sustained throughout the life cycle. Further, ongoing controversies persist regarding the safety of antidepressants in youth. Current interventions were developed to solely target the symptoms of rather than the underlying neurobiology. Most importantly, there is no way to accurately predict an individual patient's response to interventions. Consequently, there is a critical need for optimally targeted interventions that directly address the relevant pathophysiology of depression.
Repetitive transcranial magnetic stimulation (rTMS) targeting the left dorsolateral prefrontal cortex (DLPFC) is effective in adults with depression. rTMS is twice as likely to result in response (relative risk or RR: 2.35 \[95% confidence interval or CI: 1.70-3.25\]) and remission (RR: 2.24 \[95% CI: 1.53-3.27\] than a sham procedure Evidence in youth is also encouraging, with a 66% response rate in our pilot data (see Summary of Progress). The DLPFC plays a critical role in emotional regulation, directly connecting it to depressive symptomology. Our lab and others have clearly implicated structural and functional deficits in the DLPFC in youth with MDD. What is not known is what biomarkers best predict response, remission, and recovery with rTMS in youth with treatment resistant MDD. As response is not universal, this is a significant gap in our knowledge. Our basic model is that rTMS increases expression of BDNF, up-regulates activity of endocannabinoids, increases glutamate concentrations, and increases DLPFC activity - correcting the deficit seen in MDD. These biologic changes enhance executive control of mood state (see our pilot data in the Summary of Progress). These positive effects may be moderated by comorbidity (i.e., social phobia) and genotype (i.e., BDNF). How this model fits with response, remission, and recovery has yet to be fully tested and this information has the potential to be directly clinically meaningful. The central aim of the project is to evaluate predictors of rTMS response, remission, and recovery based on integrated neuroimaging, physiological, and clinical measures. While not a clinical trial per se (efficacy is not the primary outcome measure), we will use a non-randomized sham lead in to a single active (rTMS) arm study design as a framework for biomarker discovery.
To accomplish this goal, we will pursue the following specific aims: The primary aim is to identify baseline neuroimaging, physiological, and clinical predictors of response to 3 weeks of rTMS treatment in adolescents with treatment resistant MDD.
