The Antidepressant Effect of Intermittent Theta Burst Stimulation (iTBS)

The present study is a randomized placebo-controlled trial examining the effect of intermittent theta burst stimulation (iTBS) on unipolar depression. iTBS is a form of transcranial magnet stimulation. The anti-depressive effect of two weeks of once- a - day neuronavigated iTBS over the dorsolateral left prefrontal cortex (DLPFC) will be investigated in comparison to sham (placebo) iTBS. Previous studies have shown that iTBS is an effective treatment for reducing symptoms of depression, but it is still unclear why some patients have a strong response to iTBS, whereas others show less or no reduction to test possible factors that can explain the inter-individual response to iTBS. Measures of cognitive functions, structural and functional brain data measured by Magnetic Resonance imaging (MRi), quality of life, sleep quality, general health status, and genetic measures will be obtained to answer the goals of this study. The main hypotheses are: 1) Patients receiving iTBS will display significantly larger reductions in depressive symptoms measured by the Montgomery-Asberg Depression Rating Scale and Becks Depression Inventory II compared to patients receiving sham stimulation. 2) Reduction in depressive symptoms will be significantly associated with a concomitant improvement in executive functions measured by neuropsychological tests. 3) Stronger connectivity at baseline between the DLFPC and the anterior cingulate cortices will be associated with better response to iTBS. 4) Variability in genetic measures will be significantly associated with treatment response to iTBS. 5) Variability in white matter structural measures of the brain will be significantly associated with the anti-depressive response to iTBS. Participants will be recruited prospectively, and the study performed at a single university hospital. After written informed consent is obtained from eligible, volunteering patients, baseline measurements will be administrated, and the patient will be allocate