Electrically induced neuroplasticity: Exploring the effects of electroconvulsive therapy for depression using high field MRI

Electroconvulsive therapy (ECT) is an effective treatment for severe depression. Unfortunately, ECT has cognitive side effects. In addition, the exact effects of ECT on the brain remain not entirely understood. In this thesis the cognitive abilities of people before ECT, after the tenth session and at 6 months follow-up will be investigated. In addition, the change in brain structure after ten ECT sessions will be quantified.
By making use of an MRI scanner with high magnetic field strength, we were able to accurately image the dentate gyrus (DG) of the hippocampus. The DG is, together with the subventricular zone (SVZ), the only region of the brain capable of neurogenesis (formation of new neurons) in adulthood. Interestingly, we found that the DG grew in size after 10 ECT sessions, which seems to reflect neuroplasticity (such as neurogenesis and the reorganization neuronal connections). Using several different MRI scans, we studied whether the increase in volume of the DG was due to edema (retention of fluid) or new blood vessels. This was not the case. Furthermore, we did not find clues for neurogenesis in the SVZ after ECT. In addition, we found that ECT caused cognitive impairment at the short term (after ten sessions), yet these impairments, on average, subside after six months.
The findings from this thesis could be used in future research directed at getting a better picture of the effects of ECT, and to investigate if we could design therapies achieving similar efficacy without the associated side effects.