"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 Francesca Filbey from Centre for Brain Health at The University of Texas at Dallas.
‘Chronic use of marijuana disrupts the natural reward circuitry of the brain that could be a marker of transition from recreational marijuana use to problematic use.’
Marijuana users had more activity in the brain's reward processes when presented with cannabis cues than with natural reward cues.
"In essence, these brain alterations could be a marker of transition from recreational marijuana use to problematic use," said Filbey.
The researchers studied 53 adult marijuana users and 68 non-users. The researchers showed the participants a series of objects to test their reward response. The objects
Include 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.
Marijuana users displayed a stronger response in several parts of their brain linked to rewards such as the orbitofrontal cortex, striatum, anterior cingulate gyrus, precuneus and the ventral tegmental area than they did when they were shown the natural fruit cues.
"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," said Filbey.
The findings appeared in the journal Human Brain Mapping.