ECT has been an acute intervention for patients with severe, pharmacotherapy-resistant major depressive episodes, but what is its effect on brain volume—given what is known about hippocampal volume changes in MDD? A team of researchers from the University of Heidelberg, Germany, sought to clarify previous, sometimes conflicting research on this subject and found that ECT directly enhances gray matter and appears to encourage brain plasticity.1
In a sample of 18 patients with MDD, the research team compared volume changes in whole-brain gray matter before and after ECT with magnetic resonance imaging and voxel-based morphometry. They also investigated the effect of ECT on cortical thickness. The average age of the study cohort was 52 years, and men and women were equally represented in the cohort. On average, study participants received 11 ECT sessions. The average Hamilton Depression Rating Scale score was 21.2 points lower after ECT than before ECT (10.7 vs 31.9), and the average Mini-Mental State Examination score shifted by 1 point (27 vs 28). A therapeutic response was achieved in 83% and remission in 56%.2
In all, a mean post-ECT gray matter increase of 3.7% was detected (43.4% vs 41.9%). The most prominent (P < .05) increases occurring over time were seen in the right temporal lobe, including the hippocampus and parahippocampal area, insula, fusiform gyrus, and amygdala. Regions of interest—including the hippocampus, amygdala, and habenula—all exhibited significant (P < .05) increases in gray matter. Voxel-based cortical thickness analysis revealed an increase in the cortical temporal pole and insula, which corroborated the cortical voxel-based morphometry results.
Several previous studies have demonstrated a correlation between ECT and gray matter increase in the hippocampus, an area of the brain shown to lose volume in the setting of MDD. That research, including the investigators’ own earlier studies in animal models, led them to postulate that ECT is neurorestorative precisely because it encourages an increase in hippocampal neurotrophic factor.3 They also stressed that neither loss of gray matter nor increase in white matter was detected in longitudinal analysis, and this observation counters the theory that gray matter growth is an indirect response to white matter loss in patients undergoing ECT.
The findings confirm several earlier studies that showed that hippocampal and amygdala gray matter volume increases after acute ECT in patients who experience acute depressive episodes. Moreover, the results may support the hypothesis that ECT enables—and restores—plasticity rather than having a detrimental effect on brain structure.
1. Sartorius A, Demirakca T, Böhringer A, et al. Electroconvulsive therapy increases temporal gray matter volume and cortical thickness. Eur Neuropsychopharmacol. 2015 Dec 29. doi: 10.1016/j.euroneuro.2015.12.036. [Epub ahead of print]
2. Bumb JM, Aksay SS, Janke C, et al. Focus on ECT seizure quality: serum BDNF as a peripheral biomarker in depressed patients. Eur Arch Psychiatry Clin Neurosci. 2015;265:227-232.
3. Sartorius A, Hellweg R, Litzke J, et al. Correlations and discrepancies between serum and brain tissue levels of neurotrophins after electroconvulsive treatment in rats. Pharmacopsychiatry. 2009;42:270-276.