Ketamine is the quickest-acting antidepressant, working within hours in comparison to more common antidepressants that can take a few weeks. Ketamine can however only be administered for a limited time due to the many side effects.1✅ JOURNAL REFERENCE
DOI: 10.1038/s41467-022-30386-5
A study has identified precisely how ketamine works so rapidly, and how it could be adapted for use as a medication with no side effects.
The study in mice reveals that ketamine functions as a fast-acting antidepressant by increasing the activity of newborn neurons, which are part of the brain’s continuous neurogenesis.
New neurons are constantly being produced at a slow rate and increasing the amount of neurons results in behavioral changes. Other antidepressants function by increasing the rate of neurogenesis, which means increasing the number of neurons, and this can unfortunately take weeks.
By contrast, ketamine provides behavioral changes just by increasing the activity of the existing new neurons. This can take place immediately when ketamine activates the cells.
The researchers identified the population of cells that are involved, which is significant because when you give ketamine to individuals now, it impacts multiple areas of the brain and leads to lots of adverse side effects. But now it’s known exactly which cells need to be targeted, medications can be designed to target only those cells.
Ketamine’s side effects include addiction, drowsiness, insomnia, vomiting, nausea, and blurred or double vision.
The objective is to produce an antidepressant that doesn’t take 3 to 4 weeks to work because individuals don’t do well throughout that time. If you’re badly depressed and start taking your drug and nothing is transpiring, that’s depressing in itself. An antidepressant that’s effective immediately would make a big difference.
The study proves that neurogenesis is responsible for the behavioral effects of ketamine. This is because these newborn neurons form connections known as synapses that activate the other hippocampus cells.
These cells function like a match, which starts a fire that ignites lots of activity in many other cells producing the behavioral effects.
It’s however not been understood that the same changes in behavior can be attained by increasing the new neuron activity without increasing the rate at which they’re born.
The researchers created a mouse for the study in which only the newborn neuron population had a receptor that permitted these cells to be activated or silenced by a drug that didn’t have an effect on any other brain cells. Researchers found that ketamine didn’t work anymore if the activity of these cells was silenced.
But the results were similar to those of ketamine if this cell population was activated by a drug. This convincingly demonstrated that it’s the activity of these cells that’s responsible for ketamine’s effects.
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