Brain, behavior, and immunity
July 1, 2025
Brandi Quintanilla, Dede Greenstein, Ashutosh Tripathi et al.
7 citations
Ketamine, a rapid-acting antidepressant, may also regulate immune function. The complement system, part of the innate immune response involved in synaptic plasticity, has been linked to depression. This analysis of data from 39 people with major depressive disorder and 25 healthy volunteers, originally part of a randomized, double-blind trial comparing intravenous ketamine (0.5 mg/kg) to placebo, measured plasma levels of complement proteins C3a and C4a at baseline, 230 minutes, Day 1, and Day 3. A significant interaction between diagnosis and sex was found for C3a but not C4a levels. Ketamine's effects on C3a and C4a did not change over time. The findings suggest that targeting the complement pathway could lead to advances in treating major depressive disorder.
Journal of affective disorders
March 1, 2025
Elizabeth D Ballard, Lucinda Neely, Laura Waldman et al.
4 citations
Suicidal ideation, depression, hopelessness, psychological pain, and traumatic stress are all elevated during a suicide crisis and respond to a single ketamine infusion. In a study of 118 adults spanning the suicide risk continuum, 14 high-risk individuals who had recently attempted or seriously considered suicide were compared with those whose crisis had resolved. A subset of 10 high-risk participants received open-label ketamine (0.5 mg/kg). Results were mixed depending on the assessment used, but all five clinical characteristics were elevated near the time of crisis and decreased after ketamine. The small sample and use of only one intervention limit the findings.
Bipolar disorders
April 2, 2025
Adam Fijtman, Mani Yavi, Abigail Vogeley et al.
2 citations
Ketamine rapidly reduces depressive symptoms in treatment-resistant depression but does not improve working memory, attention, or concentration. In a crossover trial, 21 individuals with treatment-resistant depression (14 with bipolar disorder, 7 with major depressive disorder) received ketamine or placebo infusions. Brain activity measured by magnetoencephalography during a working memory task showed increased gamma power in the parieto-occipital junction and decreased gamma power in the posterior superior temporal sulcus and inferior frontal gyrus after ketamine compared to placebo. These distinct gamma power changes in brain regions linked to attention and working memory suggest that ketamine alters neural activity without improving cognitive performance, highlighting the need for further research into its neurobiological mechanisms.