How does cannabis affect a psychopath's brain

Does cannabis cause schizophrenia?

Cannabis is mostly relaxing. However, depending on the person and situation, undesirable effects can also occur. Feelings of fear and paranoia are possible. But is cannabis also a cause of schizophrenia?

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A deep drag on the joint and a pleasant relaxation floods the body. Usual thought patterns fade into the background and new ideas and insights flow into consciousness. Sometimes you get euphoric feelings. A silly serenity can also spread among smoking friends, accompanied by a feeling of connectedness.

But there are alternatives. The jumps in thought that were previously perceived as funny can lead to an endless mess. Consumers are confused and lose their bearings. Instead of a feeling of community among friends, those affected experience themselves as marginalized or develop delusional ideas or even paranoia. Especially with high doses, the effect can get out of hand and catapult consumers into fearful states. Some develop a psychosis that does not go away even after the effects wear off. What actually is a psychosis?

Immovable conviction

An important characteristic of a psychosis are immovable beliefs that have a strong reference to the ego. In the drugcom video, Oliver reports how his thinking has developed more and more in the direction of psychosis. "I was constantly interpreting something into people, things, pictures that wasn't there." He immediately interpreted even small glances from other people as "he was watching me." His thoughts seemed to develop a life of their own tormented him at night too. The storm of thoughts culminated in his ultimately believing that he was the born again Jesus, who came to save the world.

Psychosis can be very different depending on the case, explains Dr. Jockers-Scherübl in a drugcom interview. Some of those affected are firmly convinced that they are being bugged by the secret service. Others are absolutely certain that their lives are threatened by the mafia. Of course, such things can actually happen. But people who suffer from psychosis do not question their view of things, even if it seems completely unrealistic to other people.

When psychosis persists, the most common diagnosis is schizophrenia. This is a disease in which thinking, perception and one's own experience are fundamentally disturbed. It is still not fully understood why someone develops schizophrenia. The genes probably play an important role. However, unfavorable environmental factors can increase the risk of an outbreak of disease. Research suggests that cannabis use may also play a role in this. How would you describe that?

Smoking weed flooded the endocannabinoid system

The consumption of cannabis has a psychoactive effect because the active ingredient THC binds to the body's own cannabinoid receptors. So-called endocannabinoids, which the body produces itself, usually attach to this. Endocannabinoids are only produced by the body when needed and only in the required amount. However, when cannabis is used, the endocannabinoid system in the brain is literally flooded with THC, which can cause the body to overreact. The neurotransmitter dopamine also seems to play a role here.

Experimental studies have shown that psychotic symptoms such as paranoia and hallucinations can occur at least temporarily if the THC dose is high enough. After the effects wear off, the psychotic symptoms usually go away. In some cases, like Oliver, this develops into schizophrenia.

It cannot be said whether Oliver would have become psychotic without smoking weed. However, a second bout of psychosis followed shortly after he started using cannabis again. Before that he felt completely clear in his thinking and thought that he could afford smoking weed again. During a trip to India it happened: "At some point I was convinced that I am here in Hell, all of the dark-skinned people are dead and now I have to get out of Hell and back to the living in Paradise."

Different explanatory models

However, a single case is not enough to be able to safely name cannabis as the cause. It is noticeable, however, that cannabis use is much more widespread among people suffering from schizophrenia than in the rest of the population. Studies have shown that cannabis use is associated with a 2 to 3-fold increased risk of psychosis. Various explanatory models are conceivable for this:

  1. Cannabis alone could be the cause of a psychosis that would not have broken out under other circumstances.
  2. People at risk of psychosis may also have a particular preference for smoking weed. The consumption would then be more of a consequence than a cause of a psychosis or simply an accompanying symptom without a causal connection.
  3. It is also conceivable that cannabis use can trigger psychosis, but only in people who are already susceptible to it. In these cases, cannabis use would not be the sole cause, but would only cause the underlying psychosis to break out. So weed would be the proverbial drop that brings the barrel to overflow.

Science has not yet provided a definitive answer as to which explanatory model actually applies. However, there is a body of evidence that tends to support the third assumption that cannabis is a risk factor that promotes the outbreak of psychosis.

A study from London has provided evidence that the number of people newly diagnosed with schizophrenia doubled between 1965 and 1999. During the same period, cannabis use in the population also increased. The proportion of cannabis users has also increased significantly more among patients with schizophrenia than among those affected by other psychiatric illnesses.

The theory that cannabis is a risk factor for schizophrenia is supported by the fact that cannabis users are on average around six years younger when they first develop psychosis than non-users when they first experience psychotic attacks. So it seems like smoking weed speeds up the onset of psychosis. Those who continue to smoke weed after the first outbreak of psychosis remain in treatment for longer and suffer more relapse into psychosis than people who give up smoking weed.

Dose-response relationship

A dose-response relationship has also emerged in some studies: the more it is consumed and the higher the active ingredient content, the more likely it is that psychotic symptoms will occur. Highly potent cannabis in particular, which contains a lot of THC but little cannabidiol (CBD), seems to favor psychoses. CBD is a cannabinoid that appears to mitigate the effects of THC.

Synthetic cannabinoids, which do not contain any CBD at all, but are in some cases many times stronger than THC, seem to be particularly often associated with psychotic lapses. However, these findings do not completely rule out the second assumption mentioned above, according to which people with a tendency towards psychosis also develop a preference for heavy consumption.

This is suggested, for example, by the results of a research group led by study leader Suzanne Gage. The research team statistically evaluated the available data on the genetic basis for both cannabis use and schizophrenia. As a result, there is evidence that starting cannabis use increases the risk of schizophrenia. However, the team found stronger evidence for the opposite relationship. Those who are genetically at risk for schizophrenia also have an increased risk of cannabis use.

Cannabis probably “only” one component in the development of psychosis

However, it is possible that both the susceptibility to psychosis and the propensity to use cannabis are caused by the same genes. Several studies point in this direction. A study with twins suggests that there is a dose-response relationship between the genetic risk of schizophrenia and cannabis use. This means that the greater the genetic risk for schizophrenia, the more the affected people consume.

Another study with siblings showed that cannabis can exacerbate the symptoms of a previously hidden psychosis in otherwise healthy people. A similar result emerged in a study with stoners: They had stronger psychotic symptoms when they were intoxicated if they were carriers of a certain gene variant. These people could therefore carry a genetically determined increased risk of developing a permanent psychosis such as schizophrenia.

There is therefore some evidence that smoking weed alone is not enough to trigger psychosis. There must be at least a genetic predisposition. Cannabis use would then be at least one component in the development of schizophrenia.


Many researchers believe that cannabis alone can actually trigger schizophrenia is unlikely. However, cannabis could make a decisive contribution to the breakout of a psychosis in genetically predisposed people. The consumption of highly potent cannabis strains or synthetic cannabinoids in particular could promote this development. However, it is still unclear whether psychosis can also break out in people who have no genetic predisposition.

In the meantime, the message for consumers is: Anyone who has ever experienced psychotic symptoms such as paranoia or hallucinations or knows cases of schizophrenia in the family should better refrain from using cannabis.

The self-test cannabis check provides indications of a possibly increased personal risk of psychosis.


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