The cannabis sativa, or marijuana plant, has been used by humans for over a thousand years.

It is also legal for medicinal use in various countries around the world, although its best-known use is perhaps as a recreational drug that is smoked or swallowed.

But how does it affect our minds? In three recent studies Journal of PsychopharmacologyMagazine neuropsychopharmacology and International Journal of NeuropsychopharmacologyIt has been shown how its use can affect a range of cognitive and psychological processes.

According to 2018 data, the UN Agency on Drugs and Crime reported that approximately 192 million people between the ages of 15 and 64 use recreational marijuana worldwide.

and close 35% of these consumers are between the ages of 18 and 25.

This suggests that most users are young adults whose brains are still developing, which can make them particularly vulnerable to the brain effects associated with long-term cannabis use.

Tetrahydrocannabinol is the main psychoactive component in cannabis, and its domain in the brain is the endocannabinoid system, where there are receptors that respond to the chemical components of this leaf.

These receptors have an important place in the prefrontal and limbic regions of the brain. Reward and motivation mechanisms.

These regulate dopamine, gamma-aminobutyric acid and glutamate signaling in the brain.

What does it mean? we know dopamine is involved in motivation, reward, and learning.

Glutamate and gamma-aminobutyric acid have functions in cognitive process, including memory and learning.

cognitive effects

Research says cannabis use can affect cognitive processing, especially in those with use disorders.

That is, people who have a constant urge to consume and disrupt their daily activities, such as work or study.

It is estimated that 10% of cannabis users meet the diagnosis of this disorder.

In our research, we were able to test about 39 people with this disorder (they had to be ‘clean’ on the day of the test) and compared this to 20 people who used cannabis at all or very infrequently.

We were able to show that participants with the disorder performed worse on memory tests of the Cambridge Neuropsychological Test Auto Battery (a test designed to assess the brain’s capacity to hold data) compared to other participants who had never or rarely had it. consumed.

Consumption has also been shown to negatively affect “executive functions”, which are mental processes that involve flexible thinking.

This effect appears to be related to the age at which drug use begins: the younger, the more executive functions are affected.

In light users, damage was also detected in the cognitive process. This group tends to make riskier decisions than others and has more problems with planning.

Although many studies have been done in men, Difference in effects in different sexes.

We showed that female users of cannabis had more attention problems and executive dysfunctions, while male users had poor memory and difficulty recognizing objects.

These differences persist when studies are conducted taking into account age, IQ, alcohol and nicotine consumption, mood and anxiety symptoms, emotional stability, and compulsive behavior.

Motivation and mental health

Marijuana use affects how we feel and also how we think.

For example, some previous research suggests that reward and motivation—along with the brain circuits involved in these processes—may be affected when we use marijuana.

This may affect our performance at school or work and It makes us less motivated to work and less rewarded when we do well.

In our recent study, we used an imagination task in which participants were scanned with a scanner where they saw the blue and orange squares.

If the participant responds, the orange squares will lead to a cash prize.

This model helped us investigate how the brain responds to rewards.

We focus specifically on the ventral striatum, a key region in the brain’s reward system.

We noted that, along with the direct effects of cannabis on the ventral striatum, the effects on the reward system are subtle.

However, the participants in our study were moderate cannabis users. The effects may be more pronounced in chronic users.

There is also evidence of marijuana. can lead to mental health problems.

We reported that it is associated with high anhedonia, which is a state of lack of pleasure in adolescents.

psychotic problems

This effect was also felt with some frequency during the covid-19 pandemic quarantines.

Cannabis use in adolescents was also considered a factor for the development of psychotic episodes in addition to schizophrenia.

One study shows that moderate cannabis use increases the risk of psychotic symptoms in teens, but has a greater effect on those predisposed to psychosis (scores high on a symptom checklist of paranoid ideas and psychoticism).

Evaluating 2,437 adolescents and young adults (14-24 years), the authors reported a six-point increase (from 15% to 21%) in the risk of psychotic symptoms in cannabis users among those without a predisposition to psychosis.

However, there was a 26 point increase in the risk of psychotic symptoms – from 25% to 51% – in cannabis users prone to psychosis.

We don’t really know why marijuana is linked to psychotic episodes, but several hypotheses suggest that dopamine and glutamate may be important in the neurobiology of these conditions.

Another study of 780 adolescents suggests that the association between marijuana use and psychotic experiences is linked to a region of the brain called the uncus.

It is located in the parahippocampus (involved in memory) and olfactory bulb (involved in the processing of odors) and has multiple cannabinoid receptors.

Consequently, the cognitive and psychological effects of cannabis use are likely it depends to some extent on dose (frequency, duration and effect), gender, genetic sensitivities and age of onset.

However, we need to determine whether these effects are temporary or permanent. An article summarizing several studies suggested that with moderate cannabis use, the effects may be weakened after periods of abstinence.

But even if that’s the case, it’s worth considering the effects of long-term use on our minds, especially for young people whose brains are still developing.

*This manuscript was authored by Barbara Jacquelyn Sahakian and researchers Christelle Langley, Martine Skumlie, and Tianye Jia, who work on mental health and neurodegeneration issues at the NIHR Cambridge Center for Biomedical Research (BRC) and NIHR MedTech and In Vitro Diagnostic Cooperative (MIC). .