Research studies of the past decade have demonstrated the efficacy of ketamine-assisted therapy in the treatment of major depressive disorder (MDD). Today, ketamine is the only FDA-approved psychedelic substance widely used for mental health treatment, however, due to limited research on ketamine as a stand-alone intervention for depression, most clinicians continue to require patients undergoing ketamine therapy to also take antidepressants. A new study offers a potential departure opportunity from this approach.
A recent retrospective study conducted in Canada analyzed data of 220 adults with treatment-resistant depression (TRD) who had four to six IV ketamine infusions for MDD between August 2018 and May 2021. The study relied on self-reported outcomes (i.e., antidepressant, anti-suicidality, antianxiety, and anti-functional impairment). They compared 39 participants not currently using other antidepressants with 181 using at least one antidepressant.
Both groups demonstrated clinically and statistically significant improvements from depressive symptoms, however, the monotherapy group reported a significantly greater reduction in suicidal ideation (SI).
Healio reports "The monotherapy group had a significantly greater reduction of its mean Depressive Symptomatology-Self Report 16-Item subscore for SI (0.91 points, SD = 0.9) than the adjunct therapy group (0.37 points, SD = 0.8)". These findings pave the way for more research into utilizing ketamine as a stand-alone therapy for some patients with MDD.
The study did not find any significant differences in the reduction of anxiety, functional impairment, or general depressive symptoms between the two groups.
The researchers noted "Future research should endeavor to determine which patients are most likely (or less likely) to benefit from combination treatment versus monotherapy in persons with MDD,” they wrote. “Moreover, whether a specific combination of ketamine and monoaminergic-based antidepressant is optimal also awaits empirical confirmation.”