How ketamine works: Researchers reveal what the drug does to the brain to treat depression

Ketamine and esketamine have multiple medical uses. Both are used frequently - intravenously as a general anesthetic and more recently as a nasal spray to give provide rapid relief to sufferers of treatment-resistant depression (TRD), anxiety, PTSD, and other mental health conditions.

How Ketamine affects different parts of the human brain was the focus of a new study, led by neuroscientist Claudio Agnorelli, following findings of previous trials using animals.

How Ketamine affects the brain

Before the trial, the brains of 11 volunteers, male adults with no underlying conditions were examined and imaged using positron emission tomography (PET) and magnetic resonance imaging (fMRI) scans.

The participants were split into two groups - all received an intravenous dose of ketamine. The first group were reassessed with new scans 24 hours after getting the drug, the second group was scanned a week later.

Researchers were able to measure levels of blood flow to different parts of the brain, and determine how cerebral activity altered after just one single dose of ketamine.

The study revealed that the drug helped lower sensory regions of the brain to start directly communicating with the higher levels - the areas that are responsible for complex thought and orchestrating brain processes.

Ketamine thearapy is still in its early stages of development and doctors acknowledge that administering the drug may not work for everyone. The findings of the Imperial College London study have not been peer-reviewed yet, and they stress that the “results are preliminary”.

Who can be prescribed ketamine to treat depression?

Esketamine was approved by the FDA in 2019 and is available on medical prescription to treat TRD - the spray is generally used alongside other over-the-counter antidepressants. It has been shown that esketamine can significantly reduce depression symptoms. Doses are taken twice weekly for month, then gradually reduced.

Ketamine thearpy is not advised for children or adolescents, and is only given to patients who have tried at least two other antidepressants without success.

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