Changes in brain connectivity related to the treatment of depression measured through fMRI: a systematic review.

Esteve Gudayol-Ferré,Maribel Peró-Cebollero,Joan Guàrdia-Olmos,Andrés A González-Garrido

doi:10.3389/fnhum.2015.00582

Abstract

Depression is a mental illness that presents alterations in brain connectivity in the Default Mode Network (DMN), the Affective Network (AN) and other cortical-limbic networks, and the Cognitive Control Network (CCN), among others. In recent years the interest in the possible effect of the different antidepressant treatments on functional connectivity has increased substantially. The goal of this paper is to conduct a systematic review of the studies on the relationship between the treatment of depression and brain connectivity. Nineteen studies were found in a systematic review on this topic. In all of them, there was improvement of the clinical symptoms after antidepressant treatment. In 18 out of the 19 studies, clinical improvement was associated to changes in brain connectivity. It seems that both DMN and the connectivity between cortical and limbic structures consistently changes after antidepressant treatment. However, the current evidence does not allow us to assure that the treatment of depression leads to changes in the CCN. In this regard, some papers report a positive correlation between changes in brain connectivity and improvement of depressive symptomatology, particularly when they measure cortical-limbic connectivity, whereas the changes in DMN do not significantly correlate with clinical improvement. Finally, some papers suggest that changes in connectivity after antidepressant treatment might be partly related to the mechanisms of action of the treatment administered. This effect has been observed in two studies with stimulation treatment (one with rTMS and one with ECT), and in two papers that administered three different pharmacological treatments. Our review allows us to make a series of recommendations that might guide future researchers exploring the effect of anti-depression treatments on brain connectivity.

Highlights

Major Depressive Disorder (MDD) and other depressive mood disorders present numerous structural and functional alterations of the encephalon associated both to the physiopathology of depression and its diverse symptomatic manifestations (Rogers et al, 2004; Fitzgerald et al, 2014; Wise et al, 2014)
After searching and applying the criteria, we found 19 articles measuring changes in brain connectivity associated to antidepressive response (Anand et al, 2005; Chen et al, 2008; Aizenstein et al, 2009; Lisiecka et al, 2011; Wu et al, 2011; Beall et al, 2012; Perrin et al, 2012; Abbott et al, 2013, 2014; Andreescu et al, 2013; Heller et al, 2013; Li et al, 2013; Posner et al, 2013; Baeken et al, 2014; Liston et al, 2014; Salomons et al, 2014; Wang et al, 2014; Wei et al, 2014; Yang et al, 2014)
The goal of the current paper is to review the studies investigating the effect of antidepressant treatment on brain connectivity

Summary

Introduction

Major Depressive Disorder (MDD) and other depressive mood disorders present numerous structural and functional alterations of the encephalon associated both to the physiopathology of depression and its diverse symptomatic manifestations (Rogers et al, 2004; Fitzgerald et al, 2014; Wise et al, 2014). Functional Magnetic Resonance Imaging (fMRI) allowed us to spot differences in the activation of these and other brain areas, so that, in depressive symptoms, we find— rather consistently—an increase in the activation of the mPFC, the amygdala, and the hippocampus in depressed subjects with respect to the control subjects (Rose et al, 2006; Siegle et al, 2007; Wise et al, 2014) It is likewise common for depressed patients to show fewer activations than healthy persons on the LPFC, the inferior parietal lobe (BA 40), the posterior cingulate cortex (PCC), and the striatum, among other structures (Rose et al, 2006; Siegle et al, 2007; Wise et al, 2014). Affective disorders have been linked to alterations of the Default Mode Network (DMN), the Affective Network (AN), the Salience Network (SN), and the Cognitive Control Network (CCN), among others (Dutta et al, 2014)

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