Effects of intermittent theta- burst stimulation on emotion anticipation and processing in depression- investigating behavioral, electrodermal and neural activity

BACKGROUND: Depression is characterized by disturbed emotion processing. Repetitive transcranial magnetic stimulation, and its development intermittent theta- burst stimulation (iTBS), induces brain network changes and is an emerging treatment alternative for depression. In this sham- controlled study, we aimed at studying the effects of iTBS on emotion anticipation and processing in depression. METHODS: 42 patients with depression were allocated to receive active or sham iTBS treatment. Before treatment (baseline) and four weeks after baseline (follow- up), participants underwent functional magnetic resonance imaging (fMRI) scanning with simultaneous recordings of skin conductance responses (SCR). During scanning, participants were presented to an emotion anticipation and processing paradigm. Behavioral data (symptom ratings and ratings of emotional stimuli) were also collected. RESULTS: There were no differences in behavioral, skin conductance or neural activity after active, compared with sham, treatment. However, across groups, SCRs to positive anticipation increased and SCRs to negative processing decreased at follow- up. Additionally, amygdala and right insula reactivity to negative processing, and right amygdala reactivity to positive processing, decreased at follow- up. Increased ACC activity after active treatment to positive anticipation and processing was correlated with decreased anhedonia symptoms. CONCLUSIONS: Active, compared with sham, iTBS treatment does not affect behavioral, skin conductance or neural activity to emotion anticipation and processing in depression. However, across treatment groups, changes occur with time, perhaps reflecting normalization processes or partial treatment effect of sham iTBS. The ACC seems to be involved in the treatment mechanism of iTBS.