Neuroimaging Correlates of Treatment Response to Transcranial Magnetic Stimulation in Bipolar Depression: A Systematic Review

Abstract

Transcranial magnetic stimulation (TMS) has become a promising strategy for bipolar disorder (BD). This study reviews neuroimaging findings, indicating functional, structural, and metabolic brain changes associated with TMS in BD. Web of Science, Embase, Medline, and Google Scholar were searched without any restrictions for studies investigating neuroimaging biomarkers, through structural magnetic resonance imaging (MRI), diffusion tensor imaging (DTI), functional MRI (fMRI), magnetic resonance spectroscopy (MRS), positron emission tomography (PET), and single photon emission computed tomography (SPECT), in association with response to TMS in patients with BD. Eleven studies were included (fMRI = 4, MRI = 1, PET = 3, SPECT = 2, and MRS = 1). Important fMRI predictors of response to repetitive TMS (rTMS) included higher connectivity of emotion regulation and executive control regions. Prominent MRI predictors included lower ventromedial prefrontal cortex connectivity and lower superior frontal and caudal middle frontal volumes. SPECT studies found hypoconnectivity of the uncus/parahippocampal cortex and right thalamus in non-responders. The post-rTMS changes using fMRI mostly showed increased connectivity among the areas neighboring the coil. Increased blood perfusion was reported post-rTMS in PET and SPECT studies. Treatment response comparison between unipolar depression and BD revealed almost equal responses. Neuroimaging evidence suggests various correlates of response to rTMS in BD, which needs to be further replicated in future studies.

Are There Biological Correlates of Response to Yoga-Based Interventions in Depression? A Critical Scoping Review

“…Experts in the field believe that there is a need to move beyond these biomarkers and to investigate novel predictors of treatment response in depression, such as measures of DNA methylation or protein expression, in combination with digital methods of phenotyping and machine learning [ 114 , 115 , 116 , 117 ]. In contrast, most studies of YBI in depression have used biological correlates that have already been extensively investigated and found to be of limited specificity and predictive power [ 52 , 56 , 92 ]. Similarly, though neuroimaging and cognitive findings have yielded the best effect sizes for prediction of antidepressant response [ 52 ], only three of the studies reviewed here made use of these markers [ 76 , 80 , 82 ].…”

“…Most studies of treatment response in depression have evaluated biomarkers in relation to antidepressant drug therapy. However, these markers may also be useful in evaluating the response to other forms of treatment, such as electroconvulsive therapy [ 55 ], repetitive transcranial magnetic stimulation [ 56 ], and psychotherapies such as cognitive behavioral therapy (CBT) [ 57 ].…”

Resilience and Vulnerability to Stress-Induced Anhedonia: Unveiling Brain Gene Expression and Mitochondrial Dynamics in a Mouse Chronic Stress Depression Model

“…Growing evidence has related altered brain metabolism to the key symptoms of Major Depressive Disorder (MDD) and conditions associated with this disease [1,2], as well as stress-related pathologies [3][4][5] and other neuropsychiatric conditions sharing clinical features with MDD [6][7][8][9][10]. Conversely, early studies have shown that 70% of patients diagnosed with mitochondrial disorders met the diagnostic criteria for mental disorders, including depression and cognitive problems [11].…”

“…Anhedonia, decreased sensitivity to a reward, is considered a key feature of MDD [65,66]. Unlike another core symptom of this disorder, depressed mood [9,10,67], it can be induced and measured in small rodents [67,68]. In MDD patients, hedonic deficit was previously established to be associated with cognitive symptoms [41,42], impaired plasticity in the hippocampus [67,68], and other key neurochemical and cellular correlates of MDD [67,68].…”