In treatment-resistant depression, repeated ketamine infusions showed greater antidepressant effects than the active placebo midazolam after five doses, but when compared head-to-head against a single ketamine infusion added to midazolam over two weeks, the difference was not statistically significant. Fifty-four participants completed all six infusions. The primary outcome, change in depression severity measured by the Montgomery-Åsberg Depression Rating Scale at 24 hours after the last infusion, did not differ significantly between the six-ketamine group and the single-ketamine group. Remission and response rates favored six ketamine after the fourth and fifth infusions, respectively, compared to midazolam before the single ketamine.
A randomized clinical trial compared mindfulness-based stress reduction (MBSR) to present-centered group therapy in 98 veterans with PTSD. MBSR led to greater reductions in PTSD symptoms, increased spontaneous alpha brainwave power in posterior sites, stronger task-related frontal theta power, and enhanced frontal theta heartbeat-evoked brain responses. Only changes in frontal theta heartbeat-evoked responses mediated the treatment effect, with source-level analysis showing that theta changes in the anterior cingulate cortex, anterior insular cortex, and lateral prefrontal cortex predicted symptom improvement. The findings suggest that mindfulness meditation improves relaxation and attentional control, but enhanced interoceptive brain capacity appears to be the primary mechanism regulating emotional disturbances in PTSD.