Ketamine Has Distinct Electrophysiological and Behavioral Effects in Depressed and Healthy Subjects
Molecular Psychiatry February 27, 2018 A. Nugent, Elizabeth D. Ballard, T. Gould et al. 254 citations
In a double-blind, placebo-controlled, randomized cross-over trial with 35 unmedicated people with major depressive disorder (MDD) and 25 healthy controls, ketamine (0.5 mg/kg) improved depressive symptoms in MDD subjects but caused modest, temporary increases in depressive symptoms in healthy controls. Both groups showed increased resting gamma power measured by magnetoencephalography. Among MDD subjects, gamma power did not directly predict the size of the antidepressant effect. However, baseline gamma power moderated the link between post-ketamine gamma and response: higher post-ketamine gamma was tied to better response in those with low baseline gamma, but the opposite pattern appeared in those with high baseline gamma. This suggests biological subtypes based on homeostatic dysregulation and cautions against inferring ketamine's mechanism solely from studies of healthy controls.