Structural and functional neuroimaging predictor and state biomarkers in depression after non-invasive brain stimulation and ECT: systematic review and meta-analysis

• Grant number: 21/04294-5
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: June 01, 2021
• End date: May 31, 2022
• Field of knowledge: Health Sciences - Medicine - Psychiatry
• Principal Investigator: Andre Russowsky Brunoni
• Grantee: Mariana Pita Batista
• Host Institution: Hospital Universitário (HU). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Associated research grant: 19/06009-6 - Non-implantable neuromodulation therapies: a perspective for the depressed brain, AP.TEM

Abstract

Non-invasive brain stimulation modalities such as transcranial direct current stimulation (tDCS) and repetitive transcranial magnetic stimulation (rTMS) present moderate response rates and heterogeneous outcomes for major depressive disorder (MDD). In addition, their mechanisms of action are poorly understood. Likewise, although electroconvulsive therapy (ECT) presents higher response rates in depression, its effects are heterogeneous and the comprehension of its mechanisms is limited. The identification of biomarkers - "objective indications of medical state" that "can be measured accurately and reproducibly" associated with the clinical outcome ("predictor biomarkers") and/or that change according to clinical response ("state biomarkers") can be useful in unveiling mechanisms of action by examining the role of these markers in the pathophysiology of the disease. Among several of them, structural and functional neuroimaging biomarkers are natural candidates for predicting NIBS and ECT response and being influenced by their effects, since they represent the underlying circuit ("target") that is stimulated by tDCS or TBS. Recently, structural and functional neuroimaging biomarkers provided by Magnetic Resonance Imaging (MRI) indicated that the volume and thickness of certain structures (e.g., portions of the prefrontal cortex and the anterior cingulate cortex), resting-state connectivity of certain networks, and connectivity between regions of interest (ROIs) predicts and are modified by NIBS antidepressant effects. Nonetheless, this evidence is preliminary as it was obtained in mostly small sample sizes in non-RCT studies. Our aim is to synthesize the best available evidence on neuroimaging biomarkers in depression using NIBS and ECT.