Intrinsic functional connectivity in late-life depression: trajectories over the course of pharmacotherapy in remitters and non-remitters

Abstract

Previous studies in late-life depression (LLD) have found that patients have altered intrinsic functional connectivity in the dorsal default mode network (DMN) and executive control network (ECN). We aimed to detect connectivity differences across a treatment trial among LLD patients as a function of remission status. LLD patients (N=37) were enrolled into a 12-week trial of venlafaxine and underwent five functional magnetic resonance imaging resting state scans during treatment. Patients had no history of drug abuse, psychosis, dementia/neurodegenerative diseases or medical conditions with known effects on mood. We investigated whether there were differences in three networks: DMN, ECN and anterior salience network connectivity, as well as a whole brain centrality measure (eigenvector centrality). We found that remitters showed increases in ECN connectivity in the right precentral gyrus and decreases in DMN connectivity in the right inferior frontal gyrus and supramarginal gyrus. The ECN and DMN had regions (middle temporal gyrus and bilateral middle/inferior temporal/fusiform gyrus, respectively) that showed reversed effects (decreased ECN and increased DMN, respectively). Early changes in functional connectivity can occur after initial medication exposure. This study offers new data, indicating that functional connectivity changes differ depending on treatment response and can occur shortly after exposure to antidepressant medication.

Depression Affects Intrinsic Brain Activity in Patients With Mild Cognitive Impairment

“…It is supported by results from previous studies about late-life depression (LLD). LLD usually has a hyperactive DMN (increased rumination, defected cognition) and a hypoactive ECN (low cognitive control associated with emotional response), which may reflect clinical features of depressive symptoms (Aizenstein et al, 2014;Karim et al, 2017).…”

Radiation‐induced brain structural and functional abnormalities in presymptomatic phase and outcome prediction

“…Animal studies [Chan et al, ; Wang et al, ], however, support our finding by showing a progressive reduction in the FA with demyelination and a steeper decline when the RT dose was high. In addition, we think that the occurrence of abnormal regional functioning and inter‐regional FC earlier (<12 months) than the white matter damage (>12 months) was reasonable because brain function might be more vulnerable or sensitive to attack [Karim et al, ]. Interestingly, similar white‐matter regions (the periventricular areas) were also found to be frequently targeted in normal aging subjects [Habes et al, ].…”

Predictors of treatment outcome in depression in later life: A systematic review and meta-analysis

“…Patel et al (2015) reported that patients with late-life depression who had lower functional connectivity in the dorsal default mode network had better treatment outcome. Karim et al (2016) reported differences in brain activity in frontal and temporal cortices involving the anterior salience network and default mode network between remitted and non-remitted late-life depression patients. Therefore, intact executive function may indicate less severe pathology or preserved ability to respond to treatment.…”