Could crystal meth literally be causing its users to go mad? In 2011, a breakthrough study found a link between heavy methamphetamine use and schizophrenia. According to researchers at Toronto’s Centre of Addiction and Mental Health (CAMH), heavy meth use is correlated with the development of schizophrenia-like psychosis.

While smaller-scale studies have identified a link between cannabis use and psychosis, this is the first large-scale study to identify a correlation between meth and a psychosis that mimics schizophrenia. Meth is one of the most commonly abused drugs in the United States; in 2009, 1.2 million Americans aged 12 or older said that they had abused meth at least once in the previous year.

Meth & Schizophrenia: What’s the Link?

For years, medical professionals have debated whether meth use is indeed associated with an increased risk for schizophrenia. Japanese clinicians, for example, have long believed that there is a link between the two. However, previously in the United States, this link was largely discounted. Many psychiatrists believed that the psychosis was already present and simply undiagnosed in meth users, according to reports by PsychCentral.

The Canadian study was a true game changer. The CAMH study found evidence that heavy meth users have a higher risk for developing schizophrenia when compared both to non-drug users as well as individuals who heavily used other drugs, but not crystal meth.

The study examined California hospital admission records dating between 1990 and 2000 for individuals who used or abused major drugs, including meth, cannabis, alcohol, cocaine, and opioids. For a control group, the study also looked at individuals who were admitted for appendicitis but had no previous history of drug use. Readmission records were analyzed to track patients who were readmitted with a schizophrenia diagnosis. Records were excluded from the study if patients were dependent on more than one drug or had a diagnosis of schizophrenia or drug-induced psychosis prior to their hospitalization.

Results from the Study

“We found that people hospitalized for methamphetamine dependence who did not have a diagnosis of schizophrenia or psychotic symptoms at the start of our study period had an approximately 1.5 to 3.0-fold risk of subsequently being diagnosed with schizophrenia, compared with groups of patients who used cocaine, alcohol or opioid drugs,” said Russ Callaghan, Ph.D., the CAMH scientist who led the study.

While a clear correlation has now been established, the manner by which meth use induces psychosis-like symptoms, however, is not fully understood. Some researchers speculate that repeated use of meth may trigger latent schizophrenia by sensitizing the brain to dopamine, a brain chemical associated with psychosis. The study’s lead scientists say that more research is necessary to full explore the correlation between meth use and schizophrenia.

“We really do not understand how these drugs might increase schizophrenia risk,” said Stephen Kish, Ph.D., senior scientist and head of CAMH’s Human Brain Laboratory.

However, it is important to note that the study’s authors cautioned that the correlation between meth use and schizophrenia does not appear to apply to individuals who take controlled doses of amphetamines or cannabis for medical purposes. The study’s founders also empathized that since this was the first study of its kind, the link between meth use and schizophrenia still needed to be confirmed.

Meth Abuse & Schizophrenia: What are the Symptoms?

Symptoms of methamphetamine abuse include behavioral changes and mood swings, including an increase in irritability, anxiety, excitement, and paranoia. Users may also experience auditory hallucinations and respond violently and disproportionately to situations as users swing rapidly between friendly behavior and hostile reactions.

According to the CAMH research study, long-term abuse can also lead to the development psychosis-like symptoms that resemble schizophrenia. According to the Mayo Clinic, these symptoms include delusions, hallucinations, disorganized thinking, and abnormal motor behavior. Delusions are false beliefs that are not based in reality and may include misguided beliefs in one’s fame or popularity, beliefs that a major catastrophe is about to occur, and beliefs that another person is in love with you or is out to get you.

Hallucinations involve seeing and hearing things that do not exist. For a person with schizophrenia, the most common hallucination is hearing voices that do not exist. Individuals may also exhibit so-called “negative symptoms”. This refers to an individual’s inability to function normally; this person may be unable to make eye contact, change facial expressions, or speak without inflection or monotone.

Seeking Help for Schizophrenia and Meth Addiction

Individuals with schizophrenia typically lack awareness about their symptoms. This is especially true for individuals who are abusing meth; the combination of drug abuse and drug-induced psychosis can make it especially difficult for these individuals to function or recognize that they need help.

If you suspect that a loved one may be suffering from meth-related schizophrenia, talk to an addiction specialist who has experience with co-occurring disorders. In order for your loved one to be healthy, it is critical to treat both your loved one’s meth addiction as well as a mental health concerns, such as schizophrenia.