Cannabis legalization: Health risks and benefits | Science | In-depth reporting on science and technology | DW | 26.01.2022

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Science

Cannabis legalization: Health risks and benefits

Better sex and protection from COVID-19 versus reduced cognitive ability and long-term damage — the science is split when it comes to the risks and uses of the cannabis plant for youth in particular.

A young person holding a joint, exhaling lots of smoke

Cannabis lowers inhibitions, but has long-term effects on cognitive abilities

Dope, weed, marijuana, hemp — cannabis goes by many different names. Humanity has known about the central Asian plant and its benefits for thousands of years. It's been used for the production of rope and textiles, but cannabis' fame comes from its use as an intoxicant and as medicine. 

Globally, cannabis is the second most commonly used psychoactive substance after alcohol and before nicotine, according to the non-representative Global Drug Survey 2021. Adolescents and young adults consume cannabis most frequently. 

Once called a dangerous gateway drug, cannabis has gained more public acceptance in recent years. In more and more countries, recreational consumption is now legal.

Better sex and protection from COVID?

So is cannabis a dangerous gateway drug or a panacea? Countless studies have been published in the past few months, some highlighting the great risks, others the great benefits of the hemp plant and its different substances.

A recently published Spanish study conducted by researchers at Almeria University found that sexual function is improved in cannabis consumers, and that they experience better orgasms.

"This improvement is usually associated with a reduction in anxiety and shame, which facilitates sexual relationships," the researchers said.

Two hands preparing a joint

Cannabis consumption is especially prevalent among young people, despite laws against it

In other words: Those who lose their inhibitions by drinking alcohol or smoking weed may have better sex.

US researchers at Oregon State University recently proposed cannabinoids as a way to prevent and treat COVID-19, because they block the virus from entering cells, potentially offering protection against a coronavirus infection.

Their study showed that the acids CBGA (cannabigerolic acid) and CBDA (cannabidiolic acid) bind the spike protein and prevent Sars-CoV-2 from entering cells, the researchers wrote in the Journal of Natural Products. Unlike the well-known tetrahydrocanabinol (THC) in cannabis, CBGA and CBDA are not psychoactive.

So the psychoactive THC leads to better sex, and cannabis acids protect against COVID-19 — talk about convincing arguments in favor of the miracle plant!

Smoking weed leads to long-term concentration problems

It's not quite that simple, though, because cannabis use can also lead to long-term cognitive impairment, especially in young people whose brains are still developing.

This was recently shown again by a new analysis of 10 meta-studies published in the journal Addiction.

The analysis of data from 43,000 participants showed that cannabis intoxication (which occurs after consuming a large amount of THC) can lead to mild to moderate cognitive impairments. It affects decision-making skills, the ability to suppress inappropriate reactions or to learn something by reading and listening, as well as the time needed to complete a mental task. And these impairments may persist beyond the duration of the intoxication.

"Cannabis use in youth may consequently lead to reduced educational attainment, and, in adults, to poor work performance and dangerous driving. These consequences may be worse in regular and heavy users," said Alexandre Dumais, Associate Clinical Professor of Psychiatry at Université de Montréal and one of the study's co-authors. 

On average, adults who consumed a lot of cannabis as adolescents perform worse on intelligence tests and tend to be less successful at school or university. But a direct correlation has not yet been proven. It is also still controversial whether cannabis use in adults can have long-term consequences.

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How dangerous is cannabis?

Young brains particularly at risk

It is undisputed, however, that cannabis use can damage young brains, since the frontal brain has not fully matured until a person is in their mid-20s.

The cerebral cortex of adolescent cannabis users is significantly thinner in certain areas than that of people in a comparison group, as shown by brain scans of 800 adolescents that were part of a study published in the journal JAMA Psychiatry last June.

The prefrontal cortex was most severely affected. That's the brain region where impulses are controlled, problems are solved and actions are planned. According to the study, teens with abnormal brain scans were more impulsive and had a harder time concentrating than other teens. And the more cannabis the teens had consumed, the more pronounced the effects were.

Increased risk of psychoses

Heavy cannabis use can also trigger psychoses, especially in adolescents.

Those who smoke weed daily are three times more likely to have psychotic episodes compared to people who have no contact with cannabis, a Europe-wide study showed in 2019.

Researchers from the psychiatric hospital at Ulm University even observed an eightfold increase in psychoses in the time period from 2011 to 2019, which they attributed, among other things, to the significantly increased THC content in many joints. 

In Europe, the amount of the psychoactive THC in cannabis doubled from 8% to 17% between 2006 and 2016, a British study showed

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S. Africa hopes to benefit from cannabis industry

The intoxicating effect of THC is reduced by cannabidiol (CBD). CBD is also used in pain management in patients with cancer, multiple sclerosis and inflammatory pain syndromes such as arthritis. But according to the British study, the CBD content in cannabis sold on the street has decreased significantly.

Regular and high THC use in adolescence can trigger not only psychoses, but also anxiety disorders, bipolar disorder or depression, experts say. However, it remains controversial whether it is really cannabis use triggering these disorders, or whether youth with such mental health problems are more susceptible to heavy cannabis consumption.

Growing public acceptance

Despite the risks and side effects as well as legal bans, cannabis is Europe's most popular illegal drug among young people. Other popular drugs such as alcohol and tobacco can be legally purchased and consumed in Germany and many other countries, although they, too, can cause serious damage to a person's health and relationships, as well as society as a whole.

The debate in many parts of the world about legalizing cannabis shows that the acceptance of the drug in the public eye is increasing. 

The new German government also wants to legalize cannabis. The coalition agreement between the Social Democrats (SPD), Greens and neoliberal Free Democrats (FDP) states: "We will introduce the controlled distribution of cannabis to adults for recreational purposes in licensed stores. This will enable quality control, prevent the distribution of contaminated substances and ensure the protection of minors. In four years, we will evaluate the law and the societal impact it's had."

Infografik showing the status of cannabis legalization across the world

Better quality through legalization?

German politicians say that legalization could above all improve the quality of the substances sold. In recent years, contaminated cannabis has become more and more common. According to the German Hemp Association, it is often mixed with sand, sugar, glass or spices.

In addition, more and more cannabis sold in the street is laced with active synthetic ingredients. These so-called synthetic cannabinoids are significantly more dangerous than THC, because they intensify the drug's effects. Consumers can experience delusions and circulatory collapse.

Cannabis is often described by society and politics as a dangerous gateway drug. But it's difficult to prove that cannabis users inevitably switch to harder drugs. However, most cannabis users have previously consumed alcohol and tobacco, so these two legal drugs can be considered much more likely to be gateway drugs.

Proponents of cannabis legalization say that decriminalization and legalization, along with a legal limit on THC content and mandatory labeling of additives, could significantly reduce the health risk if the drug is distributed through legal, state-controlled dispensaries.

If young cannabis users no longer have to hide, advocates say, it would also mean that therapy and prevention services could be provided more openly. Young people could learn about the risks of cannabis consumption and talk about their issues at home and in school without fear of legal retribution.

This article was originally written in German

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