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Even Casual Marijuana Use Can Change the Brain


Stashed in: Addiction, Brain, Drugs!, Marijuana, Health

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It speaks more to the nature of addiction than to any cognitive functions:

In the new study, the team looked at the brains of people 18-25 years old, some of whom smoked pot recreationally and some who did not. None of the participants showed any signs of being addicted to the drug.

Using different brain imaging techniques, the researchers were able to measure the volume, shape, and grey matter density of two key structures: the nucleus accumbens and the amygdala. The nucleus accumbens is involved in the reward circuit, including pleasure-seeking and motivation, and it’s strongly linked to addiction. The amygdala is involved in emotion, particularly in fear, anxiety, and the stress response, and in drug craving.

The team found that both brain structures varied in multiple ways, according to the number of joints per week the participants smoked – in other words, the more joints smoked, the more brain changes were evident. The nucleus accumbens was especially likely to show alterations in shape and density, and to be larger, as a function of joints per week.

“These are core, fundamental structures of the brain,” said study author Anne Blood, director of the Mood and Motor Control Laboratory at Massachusetts General Hospital and psychiatry professor at Harvard Medical School. “They form the basis for how you assess positive and negative features about things in the environment and make decisions about them.”

What’s interesting about the study is that it suggests that even sometimes-smokers show changes in the brain. What’s not clear is whether there were differences in the pot smokers’ behavior or cognitive function. But the authors suggest that the brain changes seen here may be a sort of precursor to addiction: Earlier studies in animals have shown that the active ingredient in pot, tetrahydrocannabinol (THC), may affect neural connectivity, which could be an early sign of a bourgeoning addiction.

“It may be that we’re seeing a type of drug learning in the brain,” said author Jodi Gilman, at Massachusetts General Center for Addiction Medicine. “We think when people are in the process of becoming addicted, their brains form these new connections.”

wan't there an article on PW that said reading for five minutes changes your brain...doesn't everything change it? 

Yes. Sleep removes toxins thereby changing the brain; alcohol adds toxins, changing the brain.

This research is significant because scientists are starting to learn which brain connections cause addiction. If they can isolate that we can begin research on dealing with it.

yes. it is not a question of change or no change, but what type of changes you want to make for your brain.  

reminds me of one of Pete Holmes' best monologues...

Heh, that was excellent. Some change is good.

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