Ketamine Treatment For Major Depression: Study Finds Serotonin Is Key

There's a growing interest in using the anesthetic drug ketamine as a treatment for major depression that doesn't respond to therapy and other pharmaceutical drugs. In past studies, ketamine has been found to improve depression symptoms in a large percentage of participants, sometimes after a single treatment. Questions have remained over how the drug helps this condition and a new study may have the answer.

The study comes from the Karolinska Institutet, which sought to determine whether ketamine acts on the 5-HT1B serotonin receptors in the brain. Past research has found that individuals who have depression also have a low density of these receptors in their brains compared to individuals who don't have depression.

The study involved multiple phases, the first of which split 30 participants into two groups: a placebo group of 10 people who received saline and a ketamine group of 20 who received the drug. PET scans of the participants' brains were conducted both before the infusion took place and then 24 through 72 hours after the ketamine infusion.

In Phase 2 of the study, 29 participants were given twice-weekly doses of ketamine; the results, the study found, was that more than 70-percent of the participants experienced improvements in their depression. The drug, it turns out, increases the number of serotonin 1B receptors in the brain.

Karolinska Department of Clinical Neuroscience research group leader and study's last author Johan Lundberg says this is the first time a study has shown that ketamine increases these receptor numbers, explaining:

Ketamine has the advantage of being very rapid-acting, but at the same time it is a narcotic-classed drug that can lead to addiction. So it'll be interesting to examine in future studies if this receptor can be a target for new, effective drugs that don't have the adverse effects of ketamine.