JAMA psychiatry
June 1, 2026
Ben Deverett, Duan Li, Theresa R Lii et al.
1 citation
Ketamine produces distinct brain-wave patterns that may be linked to its therapeutic effects. General anesthesia selectively blocks one of these patterns—theta oscillations—while leaving another pattern, beta-gamma oscillations, intact. In 52 participants, ketamine given during anesthesia preserved beta-gamma power increases but eliminated the characteristic theta augmentation seen during awake administration. This suggests that different neurophysiologic effects of ketamine can be separated, offering a way to investigate which brain-wave changes underlie its antidepressant, analgesic, or dissociative properties.
Journal of affective disorders
July 15, 2025
Theresa R Lii, Josephine R Flohr, Robin L Okada et al.
1 citation
The endogenous opioid system may influence the placebo antidepressant response. A post hoc analysis of a randomized, placebo-controlled trial of intravenous ketamine in depressed patients undergoing routine surgery tested whether baseline opioid use affected antidepressant responses. The analysis found that baseline opioid use significantly reduced post-treatment depression severity in patients who received placebo, but not in those who received ketamine. This reduction was independent of baseline depression severity, pain intensity, and ethnicity. The findings, based on a small sample, require confirmation by prospective controlled studies. Opioid use at baseline attenuated the placebo antidepressant response independently of pain, while the antidepressant response was preserved in opioid users who received ketamine.
medRxiv : the preprint server for health sciences
November 2, 2024
Theresa R Lii, Josephine R Flohr, Robin L Okada et al.
preprint
The placebo antidepressant response was weaker in depressed patients who were already taking opioid medications, independent of their pain levels. In a re-analysis of a randomized trial, patients on chronic opioid therapy who received a placebo showed depression scores 10 points higher on the Montgomery-Åsberg Depression Rating Scale (MADRS) across 1 to 14 days after treatment, indicating less improvement. When measured as percent change, opioid users experienced 38.4% less improvement than non-users. For patients who received ketamine, baseline opioid use did not significantly affect depression scores. Pain intensity did not predict depression outcomes, and the link between depression and pain was negligible. These results come from a small, unregistered post hoc analysis and require confirmation.