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Can Smoking Marijuana Cause Schizophrenia? Possibly.

The majority of people that smoke marijuana at some time come to wonder whether there could be any detrimental effects as a result of their habit. One of the most common questions people have is can marijuana cause schizophrenia? Much of the newer research suggests that cannabis can have a schizophrenia-like affect on the brain in regards to memory and cognition.

A study by Dr. Matthew Jones et al. at Bristol University UK discovered that cannabis causes a disruption or “disorchestration” in neural networks of the brain. This in turn would have detrimental effects on both memory and cognition. In normal individuals, specific parts of the brain are in tune with each other through brain wave activity. The rhythm of brain waves helps information process and transfer throughout the brain.

Marijuana disrupts brain waves and brain communication

Let’s use an analogy to explain how cannabis affects your brain waves and the various connected regions. Let’s say that the connected regions are street intersections with normal stop signs and stop lights. Everything is functioning as it should be and there aren’t any major accidents. Information is transferring back and forth and your cognitive processing is fine.

But now let’s introduce the ingestion of cannabis into the big picture. When the marijuana is introduced, it causes disruptions in this brain wave activity. So now instead of having a normally functioning intersection, someone cut down the stop signs and all lights turn green at the same time causing accidents. Researchers found that the cannabis introduced chaotic misfiring and connection problems between brain regions. This is why it disturbs both concentration and memory while the individual is “high.”

The bigger picture: Marijuana affects regions implicated in schizophrenia

Although the marijuana only has a subtle affect on a majority of individual brain regions, the affect as a whole is significant. It completely disrupts brain wave activity across the prefrontal cortex and hippocampal regions. These are some of the most important regions in regards to memory and making decisions. Coincidentally, both of these regions are implicated in schizophrenia.

When THC is given to healthy volunteer test subjects, it has been shown to induce psychotic symptoms, similar to those who have schizophrenia.

Link between marijuana abuse and schizophrenia

One of the reasons researchers began investigating marijuana’s link to schizophrenia in the first place is because marijuana abuse is extremely common for those with the condition. Now, researchers are finding that marijuana can actually cause schizophrenic symptoms in otherwise healthy volunteers; by causing disturbances in connectivity and wiring between various regions.

Will smoking marijuana cause schizophrenia? Not necessarily.

Does this mean that if you smoke marijuana, you will develop schizophrenia? Not necessarily – in most cases the answer is a resounding “No.” It’s important to take a critical look at the research and not get hyped up on fear. The goal is to look at the facts as a result of marijuana usage and not a skewed perspective. The fact is that when you use marijuana, you may become schizophrenia-like in regards to brain wave activity and could experience some similar symptoms.  Most researchers are still not sure about what causes schizophrenia, but we suspect it’s from a variety of contributing factors.

Using marijuana may increase risk of developing schizophrenia

In 2012, further analyzation of existing data found that disregulation of the endocannabinoid system in the brain has significant implications in regards to schizophrenia. Some researchers hypothesize that heavy marijuana use in adolescence may even increase risk of developing schizophrenia. The degree to which marijuana use is hypothesized to increase risk of developing schizophrenia is still unknown. Further research needs to be conducted to determine whether cannabis use actually can cause schizophrenia in high risk individuals.

As of now, it’s probably not a good idea to jump to conclusions in either direction. There is no causal link – marijuana smoking is not directly linked to schizophrenia. There is a correlation though, many individuals that have schizophrenia were found to have abused marijuana. If you or someone you know is at risk for developing schizophrenia (a serious mental illness), it’s probably not a smart idea to test your luck with marijuana.


  1. http://www.jneurosci.org/content/31/43/15560.full.pdf
  2. http://www.ncbi.nlm.nih.gov/pubmed/22716159
  3. http://www.drugabuse.gov/publications/marijuana-abuse/there-link-between-marijuana-use-mental-illness

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2 thoughts on “Can Smoking Marijuana Cause Schizophrenia? Possibly.”

  1. Looking for some help. My brother is 40 and is a struggling writer living in my parents basement. For years he has used marijuana. He has tried to stop but I have seen his behaviour worsen through the years, depression, anxiety. Lately, he has been talking about things he “sees” when trying to sleep. Things that hover around him or poke him in the middle of the night. Little figures or orbs that surround him. He believes he has also been abducted at some point in time. I don’t need responses of “your brothers nuts” just looking for a logical point of dialogue to see if indeed the abuse of marihuana had indeed caused my brothers brainwaves to be so disrupted, that he now has developed schizophrenic traits. I love my brother and am worried. Discussions do not help as he has a one track mind and stubborn traits. He has disengaged from much of society. He is on a government program vled AISH where a phycologist has deemed him unable to maintain himself in a standard life of work so they give him benefits.
    Looking for answers
    A lovongm brother.

  2. No one In my immediate family has schizophrenia I am 18 and I smoke marijuana once every two or three weeks I feel like I’m In a dream most of the time(without marijuana). I have anxiety problems and OCD that’s why I smoke marijuana to alliviate those problems does that mean I have schizophrenia because I am terrified.


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