This study followed 135 patients with severe depression—110 with treatment-resistant major depressive disorder (TRD) and 25 with treatment-resistant bipolar depression (TRBD)—who had already responded to an initial course of ketamine infusions. Researchers wanted to know if continuing with maintenance infusions could help sustain improvements.
Results showed that patients maintained lower depression and suicidality scores over weeks to months, with many reporting lasting relief. On average, people stayed well longer than what has typically been seen with short-term or one-time ketamine treatments. Importantly, no cases of addiction or serious safety issues were reported, although one bipolar patient did experience a switch into mania after long-term treatment.
Overall, the findings suggest that maintenance ketamine can be a safe and effective option for extending the benefits of ketamine in people with difficult-to-treat depression—though the authors note more controlled research is needed to strengthen these results