How Marijuana Really Affects the Brain

[JonLP24]

Although there’s a lot of buzz about marijuana being nonaddictive, the evidence is stacking up that people can — and do — become dependent on the drug. A study released earlier this year, for example, found that 40 percent of marijuana users in an outpatient treatment program showed signs of withdrawal, a classic indicator of addiction. Now, new research in the journal PNAS sheds light on how lighting up changes the brain — and potentially primes people for withdrawal.

It’s long been known that exposure to THC, the primary psychoactive ingredient in pot, can lead to changes in the brain. Problem is, different studies have shown different structural alterations, making it difficult to pinpoint exactly how the stuff affects people mentally. That’s why a group of researchers decided to use three different magnetic resonance imaging (MRI) techniques to examine the brains of 48 chronic marijuana users and 62 nonusers, while also assessing IQ and negative life consequences of pot smoking.

The most obvious difference: The people who regularly toked up had less volume in the orbitofrontal gyri. This brain region is part of the orbitofrontal cortex, “one of the primary areas within the reward system, which is basically a network of brain regions implicated in the addiction process,” said study author Francesca Filbey, an addiction researcher at the Center for BrainHealth at the University of Texas at Dallas. “More specifically, the orbitofrontal cortex is important for decision-making. This is the area of the brain that would learn something is good for us or bad for us.”

So why does pot cause shrinkage in this area? Simple: The orbitofrontal cortex is highly concentrated with cannabinoid receptors, the places in your brain where THC binds. As a result, it’s much more vulnerable to the effects of a chronic flood of the substance. In animal studies, “the number of those receptors decreased as a result of THC exposure as a way to regain balance in that system,” Filbey told Yahoo Health. “So too much THC basically leads to lower numbers of those receptors in the brain.”

https://www.yahoo.com/health/how-marijuana-really-affects-the-brain-102531080862.html

I wasn't sure whether to post this here or the science forum but choose here even though I don't think it should be illegal. More addictive & harmful substances are already legal & I feel it is important to know how things put into your body affect you.

After the addiction, it becomes less clear. Longer use probably would cause shrinkage or change other areas of the brain. Though I'm not sure what they mean by "withdrawal". I personally felt somewhat irritable & maybe a little anxiety but not much more than that (I usually go 6-12 months apart between a 1-2 weeks of regular use -- once in a blue moon kind a thing)

Link to study
http://www.pnas.org/content/early/2014/11/05/1415297111.full.pdf+html