ECT-related textural change in the gray matter of the limbic system in psychosis patients

519 

Abstract Submission 

Eugenie Choe^1,2, Minah Kim^1,3, Jun Soo Kwon^4,1,3

¹Department of Neuropsychiatry, Seoul National University Hospital, Seoul, Korea, Republic of, ²Department of Clinical Pharmacology and Therapeutics, Seoul National University College of Medicine, Seoul, Korea, Republic of, ³Department of Psychiatry, Seoul National University College of Medicine, Seoul, Korea, Republic of, ⁴Department of Brain and Cognitive Sciences, Seoul National University College of Natural Sciences, Seoul, Korea, Republic of

Eugenie Choe  
Department of Neuropsychiatry, Seoul National University Hospital|Department of Clinical Pharmacology and Therapeutics, Seoul National University College of Medicine
Seoul, Korea, Republic of|Seoul, Korea, Republic of

Minah Kim  
Department of Neuropsychiatry, Seoul National University Hospital|Department of Psychiatry, Seoul National University College of Medicine
Seoul, Korea, Republic of|Seoul, Korea, Republic of

Jun Soo Kwon  
Department of Brain and Cognitive Sciences, Seoul National University College of Natural Sciences|Department of Neuropsychiatry, Seoul National University Hospital|Department of Psychiatry, Seoul National University College of Medicine
Seoul, Korea, Republic of|Seoul, Korea, Republic of|Seoul, Korea, Republic of

Even though electroconvulsive therapy (ECT) is an important treatment modality for psychosis, ECT in psychosis is relatively less investigated than in depression. It is evident from non-human studies that ECT may induce histopathological alterations of the gray matter. While most studies that investigated structural changes in the brain related to ECT exposure in psychotic patients focused on macrostructural changes, such as volumetric change, such macrostructural measures are relatively crude to capture more subtle changes, such as tissue characteristics. We therefore adopted texture analysis, a methodology widely used to reflect microstructures of the brain in many pathological conditions (e.g. brain tumor, Alzheimer's disease, etc.), as a way to non-invasively quantify microstructural changes induced by ECT in psychosis patients. Especially, we focused on the limbic system, which is widely known to be involved in the effect of ECT in depression, a psychiatric condition more extensively explored in studies on ECT. Hence, we hypothesized that, in psychosis patients also, there would be microstructural changes in the gray matter of the limbic system after ECT and those changes would be correlated with clinical response.

Our dataset includes 36 schizophrenia or schizoaffective disorder patients who were treated with both ECT and medication, and 27 patients treated with medication only. Structural MRI data were acquired before and after ECT from the ECT group, and from the medication only group, twice with time interval same as that of the ECT group. After preprocessing and segmentation or parcellation, regions of interest (ROI) that constitute the limbic system were identified. For each ROI, each timepoint, and each participant, gray matter volume was estimated, and MRI texture was computed using Gray Level Size Zone Matrix (GLSZM). After feature selection from multiple interdependent GLSZM features, group-time interactions of change in volume and texture features were estimated with repeated-measures mixed model. Repeated-measures correlations between clinical variables and texture features that showed statistically significant group-time interactions were calculated. Statistical significance was set as FDR-adjusted p < 0.05.

Among twelve ROIs that constitute the limbic system, seven showed significant group-time interactions in terms of volumetric change. Among the GLSZM texture-ROI pairs, group-time interactions of Large Area Emphasis of left hippocampus and that of right amygdala reached statistical significance. For the ECT group, repeated-measures correlation revealed negative correlation between changes in multiple clinical variables and changes in Large Area Emphasis feature for both left hippocampus and right amygdala. On the other hand, medication only group did not show any significant correlation between clinical changes and changes in texture. There was also significant positive correlation between volumetric changes and change in texture in the ECT group.

Our data is in accordance with the literature in which hippocampus and amygdala have repeatedly been mentioned as key regions of ECT-related macrostructural alterations, regardless of the diagnosis of interest. Our results additionally suggest that these regions undergo more subtle, microstructural changes, and these changes are correlated with clinical response. Our study therefore implies that alteration in limbic structures constitutes a key role in the effect of ECT not only in depression but also in psychosis. It also supports that change in tissue characteristics as a result of ECT-induced neuroplasticity is one of the core mechanisms of ECT.

Non-invasive Electrical/tDCS/tACS/tRNS ²

Psychiatric (eg. Depression, Anxiety, Schizophrenia) ¹

Segmentation and Parcellation

Anatomical MRI

Limbic Systems

Psychiatric Disorders

Schizophrenia

STRUCTURAL MRI

Treatment

Other - electroconvulsive therapy