A new study by a team of Massachusetts General Hospital (MGH) researchers has revealed that repeat intravenous treatment with low-dose ketamine - an anesthetic drug typically not used as a primary treatment due it its hallucinogenic properties - can effectively reduce suicidal thoughts. The results stem from a study on a small group of patients with treatment-resistant depression.
"Our finding that low doses of ketamine, when added on to current antidepressant medications, quickly decreased suicidal thinking in depressed patients is critically important because we don't have many safe, effective, and easily available treatments for these patients," said Dawn Ionescu of MGH and lead author of the study. "While several previous studies have shown that ketamine quickly decreases symptoms of depression in patients with treatment-resistant depression, many of them excluded patients with current suicidal thinking."
Current medications to treat suicidal thoughts, such as lithium and clozapine, have serious side effects and require careful monitoring of blood levels, making them costly treatments. In addition, although electroconvulsive therapy has proven effective, it can also have severe side effects such as memory loss.
The study examined 14 patients with moderate to severe depression that, despite antidepressant treatment, experienced suicidal thoughts for three months or longer. After determining that the patients were receiving stable antidepressant treatment, they were dosed with ketamine twice weekly over a three-week period.
Patients were first intravenously administered a dose of 0.5 mg/kg of ketamine over a 45-minute period, which is around five times less than the standard anesthetic dose. After the first three doses, this was increased to 0.75 mg/kg. After the study, patients were assessed every other week as a part of the three-month follow-up period.
Before, during and after each visit and after the treatment phase, the team used the same assessment tools to analyze patient responses to the ketamine in regards to suicidal thoughts. Assessments were administered approximately four hours after the drug infusions and included medically validated measures of suicidal thinking.
Although only 12 of the 14 participants completed all of the visits, most of the patients experienced a decrease in suicidal thinking and seven of them had a complete remission of suicidal thoughts by the end of the treatment period. No serious adverse effects were noticed in connection to doses.
The current results from the MGH study show the potential for ketamine as a treatment for suicidal thoughts, although further research on larger groups of patients will need to be conducted in order to validate the new findings.
"We only studied intravenous ketamine, but this result opens the possibility for studying oral and intranasal doses, which may ease administration for patients in suicidal crises," said Ionescu. "Looking towards the future, studies that aim to understand the mechanism by which ketamine and its metabolites work for people with suicidal thinking and depression may help us discover areas of the brain to target with new, even better therapeutic drugs."
The findings were published in May 10 online issue of The Journal of Clinical Psychiatry.
