Schizophrenia and Substance Abuse

All is not what it appears to be when you begin to consider the relationship between substance abuse and schizophrenia.  Correlation and causation have been shifting like the wind as new research is revealed concerning different substances.  It’s no longer the case that we can say illicit substances don’t cause schizophrenia.  These generalized statements are now having to be broken down per substance, and we’ll talk about some of that here.

It is known that there is a class of drugs called psychedelics which completely mimic and present the user with the experience of the symptoms of schizophrenia.  It is also known that others can create a state of on-going psychosis that is hard to separate from a diagnosis of schizophrenia itself.  Making these separations become even more difficult due to the fact that people suffering withs schizophrenia are up to three times as likely to develop a substance abuse disorder versus the general population for a lifetime incidence.

schizophrenia and substance abuseIt’s hard to figure out which is the chicken and which is the egg and this is why we deal with dual-diagnosis labels in cases of schizophrenia.  The misuse of prescription medicines, street drugs, and over-the-counter substances such as tobacco and alcohol all can also interfere with treatment in many ways, but specifically through interactions with the psychiatrist-given meds and the worsening of symptoms themselves.  Clearly delineating these issues also depends upon the doctor’s ability to separate drug-induced psychosis versus a “clean” case of schizophrenia.  Let’s look further.

 Marijuana and Schizophrenia

We might as well hit the big one first.  In the United States, at the time of writing, more and more states are making the purchasing and consumption of marijuana on par with that of alcohol.  This is problematic due to the current research being released concerning the relationship between schizophrenia and marijuana.  It’s generally accepted that substance abuse can cause psychosis but not schizophrenia itself.  However, research is beginning to suggest that marijuana may indeed be able to cause schizophrenia, even if indirectly by activating some other causes.  There is research from Sweden that has placed the value at 600%.  That is, people who smoke marijuana heavily from age 18 and onward are 600% more likely to be diagnosed than those who don’t use at all.

Tobacco and Schizophrenia

As it turns out, people diagnosed with schizophrenia are up to 75-90% likely to become addicted to nicotine versus 25-30% in the general population.  Disregarding the normal horrible reasons why this is bad for anyone, it is especially bad for schizophrenics because nicotine can interfere with the effectiveness of antipsychotic drugs.  Also, attempts to quit will feature withdrawal episodes which can make the symptoms of schizophrenia flare up in a bad way.  Researchers are wondering if there is not some biological predisposition within the schizophrenic makeup which causes a craving or need for nicotine.

Methamphetamine and Schizophrenia

Of all of the street drugs out there, meth is the most likely to cause psychosis.  The research is not clear yet, but increasingly more psychiatrists are receiving cases of drug-induced psychosis which has not ceased for over a year since the last use of meth.  They are eventually diagnosing these patients with schizophrenia.  So the question becomes one of whether or not we are properly categorizing these long-term drug-induced psychosis cases, or if the drugs are truly causing schizophrenia.  We have much work to do in this area before we know for sure, and of course these are just labels we are using to communicate ideas and educate each other.  The real value is in the treatment.


Schizophrenia is complex and so is all of the data concerning it and substance abuse.  All we can say for sure is there not a singular case of substance abuse that has ever helped, and that every case in someway worsens the experience of the person dealing with schizophrenia.  We should urge all schizophrenia patients to never experiment with drugs and to certainly quit if they are using.

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