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Cannabis Induced Psychosis: Precursor to Schizophrenia?

Girls reading a book at sunset

Recently, a young man came into our office for an intake interview. He said he had been admitted to the hospital twice recently with psychosis. The hospital's original diagnosis was schizophrenia, but he did not respond well to the medication the hospital administered. The medication was stopped for further observation. Within two weeks, he was released from the hospital with no psychosis and no medication, but with a diagnosis of "Cannabis Induced Psychosis". There was no psychosis previously in his 18 years of life. He had no relatives with Schizophrenia or Bipolar I Disorder. He had never been manic or hypomanic.

Let's call him Tom, a fictional name, because the content of this article was drawn from several sources. He had been smoking cannabis for about 3 years, but more recently, he had smoked several times a day, every day. When he smoked weed, he did not become anxious nor paranoid. He was relaxed, euphoric, hungry, and sleepy. Yet, here was this young man having visual and auditory hallucinations, being paranoid and delusional and being treated with antipsychotics while he was in hospital.

Did Tom's increased use of marijuana trigger his psychosis? Was his psychosis triggered because he was predisposed to become schizophrenic? What medications would treat him most effectively? What therapy would further his treatment? Was his young age instrumental in his becoming psychotic? Did he use as much cannabis as he did to treat some mental illness not yet revealed? Is Tom more likely to become schizophrenic or psychotic later in his life? The fact is that all the questions above have vague answers because we do not know. State by State, person by person, a primitive, anecdotal, trial and error research is underway. Are there many other Toms experimenting with a substance classified as a Schedule I Drug since the 1930s with only scant research to determine its usefulness, dangers, or side effects? Yes, there are very many other Toms, and Sarahs.

We left Tom in the Crisis Intervention Center in any medium size city. There, a detailed history of his activities over the preceding couple of months would be taken. Doctors would try to determine how much marijuana, and/or, other substances Tom had used. They would learn that he knew that psychosis was "unusual behavior" for him. After all, he had smoked many times before and nothing like this had happened. Neither he, nor his parents, knew of any family members with a history of schizophrenia or psychosis.

Since he did not have a history suggestive of schizophrenia. How else did he differ?

  1. His urine and blood showed the presence of cannabis, which might also be the case with a person with schizophrenia.
  2. He had a multi-year history of frequent marijuana use. No other substances were in his system.
  3. Tom was aware that he was "different" than he had been before, "that something was wrong".
  4. He knew he had used cannabis several times every day for a few months. He estimated he may have ingested 2 grams of cannabis daily.
  5. Antipsychotic medication worsened his condition, but anti-epileptic medication improved it.
  6. He appeared to be having addictive withdrawal symptoms.
  7. Tom's psychosis resolved itself after a few days of cannabis cessation.
  8. Tom was referred to psychotherapy for "Motivational Interviewing" to aid him in quitting cannabis altogether. His Therapy goal is to prevent, or minimize, any cannabis relapse he may suffer.
  9. Noone knows what this episode means for Tom's future mental health or how his cannabis use may have affected his young brain.
  10. The cannabis Tom was using was up to 10 times stronger than that his parents might have used.

In Tom's case, he was not apparently the victim of an emergent schizophrenia. He was able to be bought out of his psychosis. It could have been different. The therapists at Family Guidance Centers of Chesterfield and Powhatan see many clients with many different circumstances. As an insurance company is wont to say, "We have seen a thing or two-therefore, we know how to do a thing or two".

Call for help when you need it. Our addresses and phone numbers follow.

Dr. D. Ray Sirry, ACSW, Licensed Clinical Social Worker, is a Clinical Associate with Family Guidance Centers in our Chesterfield office. He provides individual, child, family, and marital therapy. Dr. Sirry has experience reaching over 30 years. He can be reached at 804-743-0960 or can be emailed at

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