Ketamine acts in hours, not weeks like traditional antidepressants. Ketamine works on a completely different part of the brain than other antidepressants. Traditional antidepressants act on the monoamine system of the brain, targeting serotonin, norepinephrine or similar neurotransmitters.
Ketamine is different. It targets a completely separate system called the glutamate system.
By targeting the glutamate system, it stimulates a molecule called Brain-Derived Neurotrophic Factor (BDNF), which has been coined “Miracle-Gro for the brain” because it is associated with the growth of new branches on nerve cells as well as more connections between the neurons. Under electron microscopy, you can see these nerve connection reach out and flourish.