Longtime marijuana use can disrupt brain’s reward process: Study

Posted by Sagar Satapathy on June 10, 2016.

A recent study conducted at the University of Texas found that long term use of marijuana can disrupt the brain's natural processes.

In a paper published in ‘Human Brain Mapping’, researchers showed for the first time with functional magnetic resonance imaging that long-term marijuana users had more brain activity in the mesocorticolimbic-reward system when presented with cannabis cues than with natural reward cues.

“This study shows that marijuana disrupts the natural reward circuitry of the brain, making marijuana highly salient to those who use it heavily,” said one of the researchers Dr. Francesca Filbey from Centre for Brain Health at the University of Texas in Dallas.

During the survey, the researchers studied 59 adult marijuana users and 70 nonusers, accounting for potential biases such as traumatic brain injury and other drug use. Study participants rated their urge to use marijuana after looking at various visual cannabis cues, such as a pipe, bong, joint or blunt, and self-selected images of preferred fruit, such as a banana, an apple, grapes or an orange.

They found that users had more brain activity in the mesocorticolimbic-reward system when shown the first set of images than non-users, suggesting that these brain alterations reveal when a person’s use has crossed from recreational to potentially harmful. On average, marijuana participants had used the drug for 12 years.

Dr. Filbey and colleagues note that there is limited information on how the drug might lead to problematic use. “We found that this disruption of the reward system correlates with the number of problems, such as family issues, individuals have because of their marijuana use,” he said.

Notably, an increasing number of states in the USA have been legalizing marijuana for both medical and recreational purposes though the cannabis is considered to be the most commonly used illicit drug.

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