New Form of Brain Stimulation Targeting Dorsomedial Prefrontal Cortex in Treating Refractory Depression and the Predictive Biomarkers of Antidepressant Efficacy
Major depressive disorder (MDD) is a common and troublesome disorder, with high risk of physical and psychiatric comorbidity. At least one-third of patients could not achieve a response after several antidepressant trials, so-called treatment-refractory depression (TRD). The high-frequency repetitive transcranial magnetic stimulation (rTMS) or intermittent theta-burst stimulation (iTBS) at left-sided dorsolateral prefrontal cortex (DLPFC) have a response rate of 40-60%. Obviously, not all TRD patients achieve the remitted state after treatment with antidepressants or DLPFC-rTMS, which may result from the heterogeneity of MDD. More and more evidence, such as brain lesion studies, deep brain stimulation, open-labeled rTMS case series, and neuroimaging studies, suggests that dorsomedial prefrontal cortex (DMPFC) might play a more central role in the pathophysiology of major depression. The DMPFC demonstrated as a dorsal nexus phenomenon in depression, which means a unique brain region where cortical networks for affect regulation, default mode control and cognitive control coverage in depressed subjects but not in healthy persons. In addition, another meta-analysis of resting-state functional MRI (fMRI) demonstrated the abnormal functional connectivity from DMPFC. These abnormalities of networks were highly associated with several depressive symptoms such as anhedonia, emotional regulation, somatic markers, rumination, self-reflection, poor attention and poor decision-making. However, only a handful of studies investigated the brain stimulation targeting DMPFC and the further changes in brain functional connectivity. The clinical efficacy and the fMRI changes of prolonged intermittent theta-burst stimulation (piTBS) and 20Hz- rTMS targeting bilateral DMPFC were investigated, and the predictive value of baseline networks by fMRI for antidepressant responses was also assessed to find a reliable approach to gauge treatment response prospectively.
• Diagnosed with a recurrent major depressive disorder based on Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) criteria. Diagnoses were established after taking a thorough medical history and conducting a semistructured interview by administering the Mini International Neuropsychiatric Interview (MINI);
• Recruited participants had to have a Clinical Global Impression - Severity score of at least four and a total score of at least 18 on the 17-items Hamilton Depression Rating Scale (HDRS-17);
• Patients were qualified if they failed to respond to at least one adequate antidepressant treatment in their current episode (for example, failed to achieve 50% improvement of depression to an equivalent daily dose of 10 to 20 mg of escitalopram for at least eight weeks);
• Stabilized treatment: keeping current antidepressant drug treatment, including the dose at least for four weeks before this trial and during the trial period; keep the stabilized psychotherapy at least for three months and no anticipated adjustment of types of psychotherapy and the frequency.