You’ve probably heard of the commonly held myth about the chemical that is blamed (or credited) for the cannabis “high”: dopamine. Many media reports over the past few decades explain that THC induces a “flood of dopamine” that causes the pleasurable “high” cherished by recreational cannabis consumers.
Where did the media get this idea from? For more than four decades addiction scientists have embraced the unifying theory — the dopamine theory of addiction — that nearly all addictive substances and activities flood the limbic brain with dopamine.
Here’s how the National Institute on Drug Abuse (NIDA) explains it (emphasis mine):
THC, acting through cannabinoid receptors, also activates the brain’s reward system, which includes regions that govern the response to healthy pleasurable behaviors like sex and eating. Like most other drugs of abuse, THC stimulates neurons in the reward system to release the signaling chemical dopamine at levels higher than typically observed in response to natural stimuli. This flood of dopamine contributes to the pleasurable “high” that recreational marijuana users seek.
NIDA is not intentionally being deceptive. Through cannabinoid receptors, THC does likely activate the brain’s reward system, but it’s not likely that it does so by “flooding the brain with dopamine.” How do we know this? In contrast to early studies on animal models that support NIDA’s view — a view that to this day is shared by a (shrinking) majority of addiction scientists — the evidence is unsupported by studies on humans.
In fact, numerous human studies suggest that at best, consuming cannabis produces only a modest amount of dopamine, certainly nowhere near the five to ten times amount that’s often quoted. (Notably, the media’s description of dopamine as the brain’s ultimate “pleasure molecule” is not exactly accurate, either.) Nonetheless, while robust evidence suggests stimulants like cocaine and amphetamines do, in fact, trigger a flood of dopamine, the same cannot be said about cannabis.
In 2015, researchers at King’s College London conducted a systematic review of every published study — 25 of them, to be exact — only to find that in humans, there is “little direct evidence to suggest that cannabis use affects acute striatal dopamine release or affects chronic dopamine receptor status in healthy human volunteers.”
If not dopamine, what is responsible for cannabis’s affect on the brain’s pleasure circuitry?
In the early 1990s, the man who first identified (and synthesized) THC, Dr. Raphael Mechoulam, discovered a neurotransmitter called anandamide. Appearing to produce a heightened sense of joy and happiness, anandamide has been called the “bliss molecule.” In fact, the term anandamide comes from the Sanskrit word “ananda,” which means “joy” or “bliss.”
It turns out anandamide is responsible for much more than happiness. Anandamide also plays important roles in memory, motivation, movement, pain, appetite, fertility, even potentially inhibiting cancer cell proliferation. But it’s because of its role in neurogenesis — the formation of new nerve cells — that anandamide is also an anti-anxiety and antidepressant agent. Unfortunately, like other neurotransmitters, anandamide quickly breaks down in the body, so it doesn’t create a perpetual state of bliss. Bummer!
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