What’s the link between Cannabis and Schizophrenia & should you be worried?

Schizophrenia is a severe, lifelong mental disorder marked by impaired thinking, emotions and behaviors. It is found in one percent of the general population and in ten percent of people who have a first-degree relative with it.  Schizophrenic patients are typically unable to filter outside stimuli and may have enhanced perceptions of sounds, colors and other affects of the environment.  If untreated, most schizophrenics withdrawal from interactions with other people, and lose their ability to take care of personal needs such as grooming and eating.

To say the relationship between schizophrenia and cannabis is contested would be an understatement.  If you were to read the Wikipedia page for schizophrenia, it would tell you only about how cannabis leads to psychosis, but it doesn’t give you any numbers, links, how much one would need to smoke or at what age. In reality, using cannabis does not cause schizophrenia outright, but it can increase the likelihood for people predisposed to it. For someone to say that cannabis causes psychosis outright would be premature, as no single gene has been associated with either drug addiction or schizophrenia, so these illnesses are the result of many genes working in combination, each with a small contribution to the overall risk of developing the disorders.  There are a wide range of factors that need to be taken into account, most of which we barely understand.

THC is believed to cause transient psychotic experiences. Unlike Tetrahydrocannabinol, CBD has no mind-altering properties while being a potent medication – that’s what the National Institute on Drug Abuse (NIDA) has to say.

Since the majority of marijuana strains available on the market is THC-rich and low in CBD, it’s more likely that people who share direct contact with these substances are more likely to go under some small psychotic experiences. According to researchers, the proportion of THC to CBD presumably plays a significant role in psychotic symptoms.

The main limitation to this research is a relatively small population of people with high risk for developing schizophrenia overlapping with those who regularly enjoy cannabis. The number of such a group is estimated to 1,500 people.

In fact, cannabis impacts the very system that research suggests has a major role in schizophrenia: the endocannabinoid system, which is involved in neurotransmission and helps to regulate functions such as sleep, cognition and emotion. In the last decade, some scientists have actually started to find that the genetic variants predicting schizophrenia can also be used to predict a person’s tendency to smoke cannabis, regardless of their mental history.  In order to really hone in on the connection, one would have to conduct thorough studies of people using cannabis compared with those who don’t, both having a family history of schizophrenia.

One study from 2013 did find that increased release of dopamine from smoking marijuana is amplified in the brains of people with schizophrenia, as well as in their close relatives.  The results of this are not entirely understood, but some scientists think that, “A chronic elevation of dopamine can increase one’s likelihood of experiencing psychotic episodes, and make the disorder harder to treat.”

The brain goes through critical periods of development during childhood and adolescence. Exposure to THC, the high-inducing chemical in cannabis, during this time is a substantial environmental risk factor for schizophrenia. This risk stems from the importance of the endogenous cannabinoid system (ECS), specifically cannabinoid type I (CB1) receptors, in controlling how neurons connect and communicate with one another. Indeed, there is evidence that THC can cause psychotic episodes immediately after using cannabis, some of which can persist after the effects of THC and require clinical intervention. The risk of experiencing these psychotic episodes increases with THC dose.

Regardless, it’s important to remember that schizophrenia only affects a small number of people, so the vast majority of adolescents and young adults who use cannabis won’t develop it.  This is key because despite all the studies that link schizophrenia and cannabis, few have been able to explain why schizophrenia rates have remained stable in the face of pot’s increasing popularity among teens.  More people smoke cannabis today than ever in history.  If the connection between weed and schizophrenia is solid, then the number of people with the disease should also be going up, but it hasn’t.

CBD also has promise in improving the difficult-to-treat negative symptoms and cognitive impairment caused by schizophrenia. Studies in animals found that CBD improved some of the negative symptoms such as social interaction deficits and working memory deficits.

One significant benefit of CBD, should it prove to be an effective antipsychotic medication, is that it’s well-tolerated and has fewer side effects compared to traditional antipsychotics.

Let’s say THC (psychoactive component of cannabis) is the ‘bad guy’ in this relationship between marijuana and schizophrenia.  Fortunately, there is also a “good guy”, named CBD (cannabidiol).  There is substantial evidence of antipsychotic properties found in CBD.  CBD inhibits the breakdown of the endocannabinoid AEA, thus boosting the endocannabinoid system.  A study from UC Irvine comparing CBD with those of antipsychotic medication found that both treatments led to significant clinical improvement, but cannabidiol resulted in fewer of the common side effects – including motor impairments and weight gain – that usually lead people to stop using antipsychotic medications.

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