DNA methylation changes in association with trauma-focused psychotherapy efficacy in treatment-resistant depression patients : a prospective longitudinal study

Background: Stressful events increase the risk for treatment-resistant depression (TRD), and trauma-focused psychotherapy can be useful for TRD patients exposed to early life stress (ELS). Epigenetic processes are known to be related to depression and ELS, but there is no evidence of the effects of trauma-focused psychotherapy on methylation alterations.

Objective: We performed the first epigenome-wide association study to investigate methylation changes related to trauma-focused psychotherapies effects in TRD patients.

Method: Thirty TRD patients assessed for ELS underwent trauma-focused psychotherapy, of those, 12 received trauma-focused cognitive behavioural therapy, and 18 Eye Movement Desensitization and Reprocessing (EMDR). DNA methylation was profiled with Illumina Infinium EPIC array at T0 (baseline), after 8 weeks (T8, end of psychotherapy) and after 12 weeks (T12 – follow-up). We examined differentially methylated CpG sites and regions, as well as pathways analysis in association with the treatment.

Results: Main results obtained have shown 110 differentially methylated regions (DMRs) with a significant adjusted p-value area associated with the effects of trauma-focused psychotherapies in the entire cohort. Several annotated genes are related to inflammatory processes and psychiatric disorders, such as LTA, GFI1, ARID5B, TNFSF13, and LST1. Gene enrichment analyses revealed statistically significant processes related to tumour necrosis factor (TNF) receptor and TNF signalling pathway. Stratified analyses by type of trauma-focused psychotherapy showed statistically significant adjusted p-value area in 141 DMRs only for the group of patients receiving EMDR, with annotated genes related to inflammation and psychiatric disorders, including LTA, GFI1, and S100A8. Gene set enrichment analyses in the EMDR group indicated biological processes related to inflammatory response, particularly the TNF signalling pathway.

Conclusion: We provide preliminary valuable insights into global DNA methylation changes associated with trauma-focused psychotherapies effects, in particular with EMDR treatment.

HIGHLIGHTS

• Stressful events increase treatment-resistant depression, and trauma-focused psychotherapy can be useful for these patients.
• Epigenome-wide data shows changes associated with trauma-focused psychotherapies, especially eye movement desensitization and reprocessing therapy, in treatment-resistant depression patients.
• Genes and biological pathways related to inflammatory and immune systems are among the most statistically significant results.