Rajamannar Ramasubbu

The University of Calgary | HBI · Department of Psychiatry

Deep brain stimulation (DBS) has shown therapeutic benefits for treatment resistant depression (TRD). Stimulation of the subcallosal cingulate gyrus (SCG) aims to alter dysregulation between subcortical and cortex. However, the 50% response rates for SCG-DBS indicates that selection of appropriate patients is challenging. Since stimulation influenc...

Theta burst stimulation (TBS) is approved and widely used in the treatment of treatment resistant-major depression. More recently, accelerated protocols delivering multiple treatments per day have been shown to be efficacious and potentially enhance outcomes compared to once daily protocols. Meanwhile, bilateral treatment protocols have also been i...

Accessible Summary What is known on the subject? Major depressive disorder is the most prevalent of all mental illnesses. 10%–20% of patients with depression and 1% of the population overall have treatment‐resistant depression (TRD). DBS is an emerging investigational treatment for TRD with documented clinical efficacy and safety. The framework of...

Background: Repetitive transcranial magnetic stimulation (rTMS) is recommended in Canadian guidelines as a first-line treatment for major depressive disorder. With the shift towards competency-based medical education, it remains unclear how to determine when a resident is considered competent in applying knowledge of rTMS to patient care. Given in...

Over the past 15 years, deep brain stimulation (DBS) has been actively investigated as a groundbreaking therapy for patients with treatment-resistant depression (TRD); nevertheless, outcomes have varied from patient to patient, with an average response rate of ∼50%. The engagement of specific fiber tracts at the stimulation site has been hypothesiz...

Background : Bright light therapy has been shown to improve depressive symptoms in patients with nonseasonal major depressive disorder (MDD) but there are few studies examining functional outcomes. Methods : We examined secondary functional outcomes in the 8-week randomized, placebo-sham-controlled LIFE-D trial comparing light therapy, fluoxetine,...

Introduction Pre-treatment blood oxygenation level-dependent (BOLD) functional magnetic resonance imaging (fMRI) has been used for the early identification of patients with major depressive disorder (MDD) who later respond or fail to respond to medication. However, BOLD responses early after treatment initiation may offer insight into early neural...

Background: Deep brain stimulation (DBS) is a promising investigational approach for treatment-resistant depression. However, reports suggesting changes in personality with DBS for movement disorders have raised clinical and ethical concerns. We prospectively examined changes in personality dimensions and antidepressant response to subcallosal cin...

Introduction: Deep brain stimulation (DBS) is currently an investigational treatment for treatment-resistant depression (TRD). There is a need for more DBS trials to strengthen existing evidence of its efficacy for both regulatory and clinical reasons. Recruitment for DBS trials remains challenging due to unproven efficacy in sham-controlled DBS t...

Background: Treatment-resistant depression (TRD) is a debilitating chronic mental illness that confers increased morbidity and mortality, decreases the quality of life, impairs occupational, social, and offspring development, and translates into increased costs on the healthcare system. The goal of this study is to reach an agreement on the concep...

Objective Bright light therapy is increasingly recommended (alone or in combination with antidepressant medication) to treat symptoms of nonseasonal major depressive disorder (MDD). However, little is known about its impacts on quality of life (QoL), a holistic, patient-valued outcome. Methods This study utilizes secondary outcome data from an 8-w...

Subcallosal cingulate (SCC) deep brain stimulation (DBS) is a promising therapy for treatment-resistant depression (TRD), but response rates in open-label studies were not replicated in a large multicenter trial. Identifying biomarkers of response could improve patient selection and outcomes. We examined SCC metabolic activity as both a predictor a...

Background: Deep brain stimulation (DBS) of the subcallosal cingulate (SCC) provided benefit for treatment-resistant depression (TRD) in open-label studies but failed in a recent randomized sham-controlled trial. Informed patient selection, based on reliable biomarkers, is needed to optimize outcome. We investigated if rostral anterior cingulate (...

Background Deep brain stimulation (DBS) of subcallosal cingulate cortex (SCC) is a promising investigational therapy for treatment-resistant depression (TRD). However, outcomes vary, likely due to suboptimal DBS placement. Ideal placement is proposed to stimulate 4 SCC white matter bundles; however, no quantitative data have linked activation of th...

Background: Stimulation adjustment is required to optimise outcomes of deep brain stimulation (DBS) for treatment-resistant depression, but controlled data for ideal stimulation parameters are poor or insufficient. We aimed to establish the efficacy and safety of short pulse width (SPW) and long pulse width (LPW) subcallosal cingulate DBS in depre...

Background: Electroconvulsive therapy (ECT) can lead to rapid and effective responses in major depressive disorder (MDD). However, the precise neural mechanisms of ECT for MDD are still unclear. Previous work has confirmed that thalamocortical circuits play an important role in emotion and cognition. However, the relationship between mechanisms of...

Aim Neuroimaging‐based multivariate pattern recognition methods have been successfully used to develop diagnostic algorithms to distinguish patients with major depressive disorder (MDD) from healthy controls (HC). We developed and evaluated the accuracy of a multivariate classification method for the differentiation of MDD and HC using cerebral blo...

Background Differences in the thalamocortical system have been shown in patients with major depressive disorder (MDD). Given prior evidence of phenotypic heterogeneity by the age of onset in MDD, we examined whether differences in thalamocortical connectivity could identify biological subtypes of MDD defined by the age of illness onset. Methods A...

Objective: We previously reported that morning bright light therapy is efficacious in adults with nonseasonal major depressive disorder (MDD), both on its own and in combination with fluoxetine. Given that appetitive symptoms predict response to bright light therapy in seasonal depression, we examined, in this secondary analysis, whether the same...

Background: The electrical parameters used for deep brain stimulation (DBS) in movement disorders have been relatively well studied, however for the newer indications of DBS for psychiatric indications these are less clear. Based on the movement disorder literature, use of the correct stimulation parameters should be crucial for clinical outcomes....

Arterial Spin Labeling, Perfusion MRI, Major Depression Disorder

Background Early-onset major depressive disorder (EO-MDD), beginning during childhood and adolescence, is associated with more illness burden and a worse prognosis than adult-onset MDD (AO-MDD), but little is known about the neural features distinguishing these subgroup phenotypes. Functional abnormalities of the amygdala are central to major depre...

Controls: We also applied sparse multivariate regression (elastic net) to whole-brain functional connectivity features, for the first time, to derive stable predictive features for symptom severity. Whole-brain link-weight features achieved 74% accuracy in identifying patients and were more stable than voxel-wise node-degrees. Link-weight features...

Background: Major Depressive Disorder (MDD) is highly prevalent and potentially devastating, with widespread aberrations in brain activity. Thalamocortical networks are a potential candidate marker for psychopathology in MDD, but have not yet been thoroughly investigated. Here we examined functional connectivity between major cortical areas and th...

Deep brain stimulation (DBS) of subcallosal cingulate cortex (SCC) is an investigational therapy for treatment-resistant depression (TRD) that is hypothesized to modulate brain regions involved in mood regulation (Mayberg 2005). The ideal location and extent of stimulation within the SCC to produce substantial therapeutic effects is currently unkno...

Symptom improvement in depression due to antidepressant treatment is highly variable and clinically unpredictable. Linking neuronal connectivity and genetic risk factors in predicting antidepressant response has clinical implications. Our investigation assessed whether indices of white matter integrity, serotonin transporter-linked polymorphism (5-...

This study examined the impact of childhood neglect, serotonin transporter (5-HTTLPR) and brain derived neurotrophic factor (BDNF) polymorphisms on white matter (WM) integrity in major depressive disorder (MDD) using diffusion tensor imaging (DTI). Fifty-five medication-free MDD patients and 18 controls underwent diffusion tensor imaging scanning,...

For the ICA-Clust-FE feature extraction and GLM-Clust-FE feature extraction, significant clusters were identified by comparing patients vs. controls for various ICA components or GLM contrasts (see main text for details). These label-dependent statistical comparisons were done using only training set data, never test set data, which is important to...

Supplementary material.

Background Growing evidence documents the potential of machine learning for developing brain based diagnostic methods for major depressive disorder (MDD). As symptom severity may influence brain activity, we investigated whether the severity of MDD affected the accuracies of machine learned MDD-vs-Control diagnostic classifiers. Methods Forty-five...

This study examined the impact of childhood neglect, serotonin transporter (5-HTTLPR) and brain derived neurotrophic factor (BDNF) polymorphisms on white matter (WM) integrity in major depressive disorder (MDD) using diffusion tensor imaging (DTI). Fifty-five medication-free MDD patients and 18 controls underwent diffusion tensor imaging scanning,...

Background Structural brain abnormalities have been investigated in multi-genetic and complex disorders such as major depressive disorder (MDD). Among the various candidate genes implicated in MDD, the brain-derived neurotrophic factor (BDNF) Val66Met polymorphism and 5-HT transporter gene linked polymorphism (5-HTTLPR) have garnered the most atten...

Objectives: Genotype and drug pharmacology may contribute to variations in brain response to antidepressants. We examined the impact of two antidepressants with differential actions on serotonin transporter and the 5-HHTLPR-S/Lg polymorphisms on amygdala responses in major depressive disorder (MDD). Methods: Caucasians with MDD were given either...

Importance Bright light therapy is an evidence-based treatment for seasonal depression, but there is limited evidence for its efficacy in nonseasonal major depressive disorder (MDD).Objective To determine the efficacy of light treatment, in monotherapy and in combination with fluoxetine hydrochloride, compared with a sham-placebo condition in adu...

Objectives. Subcallosal cingulate (SCC) deep brain stimulation (DBS) is a promising experimental treatment for treatment-resistant depression (TRD). Given the role of brain-derived neurotrophic factor (BDNF) in neuroplasticity and antidepressant efficacy, we examined the effect of SCC-DBS on serum BDNF in TRD. Methods. Four patients with TRD underw...

Major depressive disorder (MDD) onset during childhood/adolescence is associated with a greater illness burden and distinct clinical profile. However, limited research exists on the effect of age of MDD onset on volumetric abnormalities in para/limbic structures during adulthood. Subgenual anterior cingulate cortex (sgACC), hippocampus and caudate...

Background: Major depressive disorder (MDD) neural underpinnings may differ based on onset age and childhood trauma. We assessed cortical thickness in patients who differed in age of MDD onset and examined trauma history influence. Methods: Adults with MDD (N=36) and controls (HC; N=18) underwent magnetic resonance imaging. Twenty patients had M...

Imaging studies of major depressive disorder (MDD) have demonstrated enhanced resting-state activity of the amygdala as well as exaggerated reactivity to negative emotional stimuli relative to healthy controls (HCs). However, the abnormalities in the intrinsic connectivity of the amygdala in MDD still remain unclear. As the resting-state activity a...

Major depressive disorder is associated with significant impairment in occupational functioning and reduced productivity, which represents a large part of the overall burden of depression. To examine symptom-based and work functioning outcomes with combined pharmacotherapy and psychotherapy treatment of major depressive disorder. Employed patients...

Background / Purpose: Major depressive disorder (MDD) development likely involves the interaction of genetics and environmental stressors. The present investigation will determine if white matter connectivity abnormalities in MDD patients are associated with tri-allelic polymorphisms of the serotonin transporter and childhood trauma scores. Main...

Background: Deep brain stimulation (DBS) of the subcallosal cingulate (SCC) is reported to be a safe and effective new treatment for treatment-resistant depression (TRD). However, the optimal electrical stimulation parameters are unknown and generally selected by trial and error. This pilot study investigated the relationship between stimulus para...

Objective: Functional near-infrared spectroscopy (fNIRS) is a non-invasive optical technique for bedside evaluation of cerebral metabolism that has clinical potential for monitoring the efficacy of pharmacological treatment. In this pilot study, we investigated the cognitive effects of methylphenidate (MP) on prefrontal function using fNIRS in hea...

Most individuals with mood disorders experience psychiatric and/or medical comorbidity. Available treatment guidelines for major depressive disorder (MDD) and bipolar disorder (BD) have focused on treating mood disorders in the absence of comorbidity. Treating comorbid conditions in patients with mood disorders requires sufficient decision support...

Medical comorbidity is commonly encountered in individuals with major depressive disorder (MDD) and bipolar disorder (BD). The presence of medical comorbidity has diagnostic, prognostic, treatment, and etiologic implications underscoring the importance of timely detection and treatment. A selective review of relevant articles and reviews published...

Medical comorbidity in patients with mood disorders has become an increasingly important clinical and global public health issue. Several specific medical conditions are associated with an increased risk of mood disorders, and conversely, mood disorders are associated with increased morbidity and mortality in patients with specific medical disorder...

The experience of self is unique and pivotal to clinically relevant cognitive and emotional functions. However, well-controlled data on specialized brain regions and functional networks underlying the experience of self remain limited. This functional magnetic resonance imaging study investigated neural activity and connectivity specific to process...

Introduction: Depression is the most common psychiatric disorder after stroke that adversely affects stroke outcomes. It is often underdiagnosed and inadequately treated. Hence, there is growing interest in interventions to prevent depression in stroke patients, which is in concert with emerging data that indicate prevention of major depression in...

The investigators of the Biomarkers for Rapid Identification of Treatment Effectiveness in Major Depression (BRITE-MD) study calculated the Antidepressant Treatment Response (ATR) index, a biomarker of frontal quantitative electroencephalogram changes, af ter 1 week of escitalopram treatment and examined whether the ATR had utility as a predictor o...

In 2001, the Canadian Psychiatric Association and the Canadian Network for Mood and Anxiety Treatments (CANMAT) partnered to produce evidence-based clinical guidelines for the treatment of depressive disorders. A revision of these guidelines was undertaken by CANMAT in 2008-2009 to reflect advances in the field. There is renewed interest in refined...

In 2001, the Canadian Psychiatric Association and the Canadian Network for Mood and Anxiety Treatments (CANMAT) partnered to produce evidence-based clinical guidelines for the treatment of depressive disorders. A revision of these guidelines was undertaken by CANMAT in 2008-2009 to reflect advances in the field. The CANMAT guidelines are based on a...