Results showed nearly 50% of participants responded to ketamine and 25% achieved complete remission from TRD, as measured by scores on the Montgomery-Asberg Depression Rating Scale (MADRS).
Dr. Marie Anne Gebara
“Our pilot study suggests that IV ketamine is well-tolerated, safe, and associated with improvement in late-life TRD,” co-investigator Marie Anne Gebara, MD, assistant professor of psychiatry at the University of Pittsburgh, told this news organization.
Dr. Gebara pointed out the treatment “may not be appropriate for all patients with TRD,” such as those with a history of psychotic symptoms or uncontrolled hypertension; but “it appears to be a promising option.”
The findings were published online in the American Journal of Geriatric Psychiatry.
Lack of data in seniors
Although ketamine has been shown in prior research to rapidly reduce suicidal ideation in adults, there has been a lack of data on its efficacy and safety in older adults, the current investigators note.
“Almost 50% of older adults suffering from depression have TRD, which is a leading cause of disability, excess mortality from suicide, and dementia,” Dr. Gebara said.
She added that after two failed trials of antidepressants, “older adults have few evidence-based choices: aripiprazole or bupropion augmentation, transcranial magnetic stimulation, or electroconvulsive therapy. Novel treatments with rapid benefit are needed as long-term outcomes are poor and recurrence rates are high.”
Dr. Gebara and colleagues at five sites (Columbia University, New York State Psychiatric Institute, University of Toronto, University of Pittsburgh, and Washington University in St. Louis) each enrolled five participants aged 60 and older into the pilot study between October 2020 and November 2021, for a total of 25 participants (mean age, 71 years).
Each participant was recruited from patient registries or referred by behavioral health or primary care providers and diagnosed with TRD, which was defined as an episode of major depressive disorder without psychotic features that persisted despite two or more trials of antidepressants including at least one evidence-based second-line treatment.
Participants had to take an oral antidepressant dosage for at least 1 month prior to the start of the IV ketamine infusions, and continue their antidepressant for the length of the trial.
They received IV ketamine twice weekly for 4 weeks. The dosage was weight-dependent.
At the end of the 4 weeks, participants who achieved a MADRS total score of less than 10 or had a 30% or greater reduction from their baseline MADRS score entered another 4-week phase of the trial. This phase consisted of once-weekly administration of IV ketamine.
Larger plans
Results showed 15 of the 25 participants (60%) experienced a 30% or higher reduction in MADRS scores in the first phase of the study. The mean change in MADRS total score from the beginning to the end of the first phase was a decrease of 9.4 points (P < .01).
At the end of the continuation phase, half (48%) met criteria for response and 27% met criteria for remission.
After ketamine administration, the researchers also found an improvement in Fluid Cognition Composite Score (Cohen’s d value = .61), indicating a medium to large effect size, and in three measures of executive function.
Overall, adverse events were rare and did not keep patients from participating in the study, the investigators note. Five of the 25 participants reported infusion-induced hypertension that was transient.
Study limitations cited include the small sample size and the absence of randomization and placebo control or comparison treatment.
“We were very pleased with these findings because they establish the safety of this novel intervention in older adults,” Dr. Gebara said.
“After establishing safety and tolerability, we can plan for larger, randomized controlled trials that will allow us to determine the effectiveness of IV ketamine for older adults with TRD,” she added.
Multiple mechanisms
In a comment, Gerard Sanacora, MD, PhD, professor of psychiatry at Yale University and director of the Yale Depression Research Program, New Haven, Conn., noted multiple mechanisms likely contribute to the antidepressant effects of ketamine.
Dr. Gerard Sanacora
Dr. Sanacora has independently researched the effects of ketamine but was not involved with the current study.
“Much of the work to date has focused on the drug’s proximal effects on the glutamatergic neurotransmitter system and the resulting enhancement of adaptive neuroplasticity in several brain regions,” he said.
“However, there is also evidence to suggest other neurotransmitter systems and possibly even neuroinflammatory regulators are also contributing to the effect,” Dr. Sanacora added.
He noted that these mechanisms are also likely amplified by the “hope, optimism, expectations, and improved medical management overall that are known to be associated with treatments that require close monitoring and follow-up with health care providers.”
Dr. Gebara noted that “internal/department funds at each site” were used to support the study. She also reported receiving support from Otsuka US. Disclosures for the other investigators are listed in the original article. Dr. Sanacora has reported having “no major direct conflicts” with the study.
A version of this article first appeared on Medscape.com.