Brain-based correlates of antidepressant response to ketamine: a comprehensive systematic review of neuroimaging studies.
The lancet. Psychiatry – October 01, 2023
Source: PubMed
Summary
Ketamine shows promise as an antidepressant, but responses vary widely among patients. A systematic review of 69 neuroimaging studies involving 1,751 participants revealed no consistent biomarker for treatment response. However, notable findings included post-treatment increases in gamma power in frontoparietal regions and enhanced functional connectivity in the prefrontal cortex. Additionally, activation of the striatum was linked to positive outcomes. While definitive biomarkers remain elusive, these insights highlight areas for future exploration in understanding ketamine's effects on depression.
Abstract
Ketamine is an effective antidepressant, but there is substantial variability in patient response and the precise mechanism of action is unclear. Neuroimaging can provide predictive and mechanistic insights, but findings are limited by small sample sizes. This systematic review covers neuroimaging studies investigating baseline (pre-treatment) and longitudinal (post-treatment) biomarkers of responses to ketamine. All modalities were included. We performed searches of five electronic databases (from inception to April 26, 2022). 69 studies were included (with 1751 participants). There was substantial methodological heterogeneity and no well replicated biomarker. However, we found convergence across some significant results, particularly in longitudinal biomarkers. Response to ketamine was associated with post-treatment increases in gamma power in frontoparietal regions in electrophysiological studies, post-treatment increases in functional connectivity within the prefrontal cortex, and post-treatment increases in the functional activation of the striatum. Although a well replicated neuroimaging biomarker of ketamine response was not identified, there are biomarkers that warrant further investigation.