- Smoking cannabis affects the reward centre in a user's brain, scans show
- That is the region responsible for releasing 'pleasure' hormone dopamine
- In cannabis users, scans show less activity in the reward centre, so a smaller amount of dopamine is released
- That dampened, blunted emotional response means a marijuana smoker will need more of the drug to illicit the same reward - raising addiction risk
By LIZZIE PARRY FOR DAILYMAIL.COM PUBLISHED: 07:21 EST, 7 July 2016 | UPDATED: 07:37 EST, 7 July 2016
For most people, the idea of winning some money will ignite a rush of emotions - joy, anticipation, excitement.
If you were to scan their brains at that very moment, you would see a surge of activity in the part of the brain that responds to rewards.
But, for people who've been smoking cannabis, that rush is not as big - and gets smaller and smaller over time, new research suggests.
And that dampened, blunted response may actually increase the risk that marijuana users are more likely to become addicted to pot and other drugs.
Smoking cannabis dampens activity in the brain's reward centre, a new study has shown. The blunted emotional response it provokes, increases the risk that marijuana users will become addicted to the drug, and other addictive substances
Dr Mary Heitzeg, senior author of the new study, a neuroscientist from the University of Michigan Medical School, said: 'What we saw was that over time, marijuana use was associated with a lower response to a monetary reward.
'This means that something that would be rewarding to most people was no longer rewarding to them, suggesting but not proving that their reward system has been "hijacked" by the drug, and that they need the drug to feel reward - or that their emotional response has been dampened.'
The findings come from the first long-term study of young marijuana users, that tracked brain responses to rewards over time, and is published in the JAMA Psychiatry. They reveal measurable changes in the brain's reward system with cannabis use - even when other factors like alcohol use and cigarette smoking were taken into account.
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