Smoking cannabis every day can distort brain activity, research suggests

'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. Continued marijuana use despite these problems is an indicator of marijuana dependence'

Researchers believe it is the first time scientists have proven it is possible to identify chronic marijuana use from brain activity following visible cues (Getty)

Smoking cannabis on a regular basis changes the brain’s natural reward circuits, according to new research. This could affect peoples’ ability to make decisions and maintain relationships as their perspective on risks and rewards is altered.

It is believed that this is the first time scientists have proven it is possible to identify chronic marijuana users from how their brains respond to cannabis cues compared to natural reward cues. The research suggested it is possible to identify whether someone’s drug use is recreational or problematic based on their brain activity.

As part of the study, 59 marijuana users and 70 nonusers were studied with functional magnetic resonance imaging, a procedure that uses MRI technology to measure brain activity by detecting changes in blood flow. Researchers presented both groups with visual cues associated with drug use such as bongs and joints, followed by other images such as healthy fruit.

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.

Francesca Filbey, a Neuroscience expert at the Center for BrainHealth in the US said: “This study shows that marijuana disrupts the natural reward circuitry of the brain, making marijuana highly salient to those who use it heavily. In essence, these brain alterations could be a marker of transition from recreational marijuana use 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. Continued marijuana use despite these problems is an indicator of marijuana dependence.”

Research from 2014 found that among teenagers and young adults, marijuana use was more common than smoking nicotine. Addiction rates were higher among younger age groups, with one in six teenagers who used the drug becoming dependent, compared to one in ten adults.