Högskolan i Skövde

Major Depressive Disorder (MDD) is the leading mental disease that affects an extended quantity of people in the world. In attempting to understand the psychological and brain anatomical deficits that characterize MDD, studies have identified significant abnormalities in cortical and subcortical areas in individuals diagnosed with this disorder. In addition to this, pharmacotherapy and psychotherapy are considered the most effective treatments for MDD. The use of Selective Serotonin Reuptake Inhibitors (SSRIs) as an antidepressant has shown a significant reduction in symptoms and Acceptance Commitment Therapy (ACT) as new treatment and part of Cognitive Behavioural Therapy (CBT) present relevant results besides the criticism and limitations that exist for both treatments. This thesis aims to look at the changes in the hippocampus and in the prefrontal cortex (PFC) connectivity related to MDD. Furthermore, an explanation and comparison of two treatments: antidepressants (focusing on SSRIs) and psychotherapy (CBT, and mindfulness as a ground for the third wave therapies with a special focus on ACT) will be presented. The findings confirm structural and functional damage in the hippocampus and PFC related to MDD and that SSRIs and ACT as treatments have positive effects on depression despite the limitations.