Smoking cannabis has a negative impact on your ability to learn and remember, a study has shown.

Taking the class-B drug reduces the amount of dopamine, an essential chemical, which is released in areas of the brain linked to memory and learning. Research had already found cocaine and heroin affected the release of dopamine, causing problems with behaviour and education, but this is the first time scientists have discovered long-term cannabis use has the same impact.

Professor Anissa Abi-Dargham, the study’s lead researcher from Columbia University Medical Center, said: “The bottom line is that long-term, heavy cannabis use may impair the dopaminergic system, which could have a variety of negative effects on learning and behaviour.”

She added: “We believe it is important to look more closely at the potentially addictive effects of cannabis on key regions of the brain.”

The study looked at 11 people, aged between 21 and 40, who are addicted to cannabis. They were then compared to 12 healthy adults who don’t use drugs.

The research, published in Molecular Psychiatry, found that the cannabis users had lower levels of dopamine release in the striatum, which is the area of the brain which is linked to attention, working memory and impulsive behaviour.

And the study found that lower dopamine levels led to poorer performance during tasks which tested the participants’ ability to learn and remember.

The addicts involved in the study had all been dependent on cannabis for at least seven years and smoked it on a daily basis. On average, they had started taking the drug at the age of 16 and had become reliant on it by the time they turned 20.

Study measured release of dopamine

The research team measured dopamine release using called positron emission tomography (PET) to track a specific molecule which binds to the brain’s dopamine receptors. The scientists studied several regions of the brain including the striatum, the thalamus, the midbrain and the globus pallidus.

Before the study started the addicts were made to stay in hospital for a week to ensure they didn’t take any cannabis, which could have potentially affected the results of the research. All participants were given oral amphetamine to stimulate the release of dopamine.

The fact that cannabis can interfere with a person’s learning and education may not come as a surprise to many. Research carried out on British schoolchildren by University College London in 2014 had already found that teenagers who had smoked cannabis at least 50 times performed worse in their exams than those who had stayed away from the drug.

With exams approaching and teenagers all over the UK being encouraged to spend their time revising, parents may be concerned that their son or daughter could be hampering their chances of success by smoking cannabis.

The home drug testing kit by AlphaBiolabs allows parents to quickly test their child’s urine to see if they have taken cannabis or other illegal substances including heroin, ketamine, cocaine and amphetamine. The test offers results in just five minutes and can be done in the privacy of your own home.