A recent study from the University of Cambridge has uncovered two brain phenomena that might explain some of the side effects of ketamine, a drug known for its anesthetic and pain-relief properties.
Scientists used electroencephalography (EEG) to measure brain waves in sheep sedated with ketamine and discovered insights that could explain the drug’s ability to cause out-of-body experiences and a state of complete oblivion.
The researchers observed the brain waves of sheep immediately after administering ketamine. Initially, low-frequency activity dominated while the sheep were asleep.
However, as the drug began to wear off and the sheep started to regain consciousness, the brain activity switched between high and low-frequency oscillations. These bursts of different frequencies were irregular at first but became regular within a few minutes.
This unusual pattern of brain activity, noted as the sheep came round from the ketamine, corresponded to the time when human users report feeling disconnected from their bodies. The researchers believe that these brain oscillations caused by ketamine may prevent normal processing of information from the outside world.
This discovery is part of a larger research project into Huntington’s disease, a condition that impairs brain function. The team aimed to understand why patients with this disease respond differently to various drugs.
Sheep were used as they are considered a suitable pre-clinical model for studying human nervous system disorders, including Huntington’s disease.
In the study, six sheep were given a high dose of ketamine, 24mg/kg, which is at the high end of the anesthetic range. Initially, the same response was seen with a lower dose.
However, within two minutes of administering the high dose, the brain activity of five out of six sheep stopped completely, with one sheep’s brain activity pausing for several minutes—a phenomenon not previously observed.
The researchers suggest that this pause in brain activity might correspond to what ketamine users describe as the ‘K-hole’—a state of oblivion similar to a near-death experience, followed by a feeling of great serenity.
Ketamine abusers often take doses much higher than those given to the sheep in this study, and progressively higher doses are needed to achieve the same effect. Such high doses can cause serious health issues, including liver damage, heart stoppage, and can be fatal.
At lower doses, ketamine provides pain relief and is used in situations such as frontline pain relief for injured soldiers or road accident victims.
Recently, ketamine has been proposed as a new treatment for depression and post-traumatic stress disorder (PTSD). Despite its anesthetic actions, little is known about ketamine’s effects on brain function.
For those interested in depression, studies highlight a core feature of depression and a health problem that may double your risk of depression.
Additional research suggests that PTSD, anxiety, and depression may not be mental diseases, and a single dose of a certain drug may lower anxiety and depression for up to five years.
This study was conducted by Professor Jenny Morton and her team and published in the journal Scientific Reports.
If you care about depression, please read studies about how dairy foods may influence depression risk, and B vitamins could help prevent depression and anxiety.
For more information about mental health, please see recent studies that ultra-processed foods may make you feel depressed, and extra-virgin olive oil could reduce depression symptoms.
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