New Facts About Ketamine Use for Depression

Ketamine is effective for treating depression, however, it can create dissociative symptoms such as feeling out of body or emotionally numb.
Researchers at Massachusetts General Hospital (MGH) recently discovered how ketamine interacts with distinct brain circuits to create its antidepressant and dissociative effects.
The study, which was published in Nature Communications, could lead to new depression treatments with fewer adverse effects.
The study included ten epileptic patients who had electrode implants in their brains to detect aberrant electrical activity that produces seizures. Before undergoing general anesthesia for electrode removal surgery, the patients were given ketamine.

They collected data on individuals’ brain activity before and after ketamine administration before removing the electrode implants.

The electrode recordings demonstrated that it produces its antidepressant and dissociative effects by engaging separate neural circuits in discrete frequency-dependent patterns of brain activity.

Ketamine caused “gamma oscillations” (25 to 55 Hz) in depression-related brain regions, notably the prefrontal cortex and hippocampus. It caused a 3 Hz oscillation in the posteromedial cortex, which is associated with dissociative symptoms.

“In this study, we show, for the first time to our knowledge in humans, a detailed description of the principal oscillatory changes in a variety of cortical and subcortical structures after administration of a subanesthetic dose of ketamine,” says lead author Fangyun Tian, Ph.D., an Instructor in the Department of Anesthesia, Critical Care and Pain Medicine at MGH and an Instructor in Anesthesia at Harvard Medical School.

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