A common belief pertaining to illegal drug use is that it can cause schizophrenia, but many researchers believe this to be untrue. Drug use is common among approximately 50% of people with schizophrenia as the patient’s way to alleviate their symptoms. However, according to the Addiction Center, it is argued that drug use for those who are genetically susceptible to schizophrenia is an environmental trigger. One study found that those who were genetically predisposed to schizophrenia had a 30% increased risk of diagnosis with the use of cannabis. The medical director of the National Alliance on Mental Illness, Ken Duckworth, states that researching this debate any further would be unethical and unlawful because the study would require researchers giving cannabis to those at risk of schizophrenia.
Coincidentally, drug use can often lead to symptoms that may look very similar to the symptoms of schizophrenia. Drugs such as psychedelics, methamphetamines, cannabis, cocaine, alcohol, recreational drugs, and prescription drugs can cause psychosis. The effects of these drugs can be similar to the symptoms of schizophrenia, in particular, hallucinations and delusions. This is called drug-induced psychosis.
While drug-induced psychosis and schizophrenia are similar in their common symptoms of hallucinations and delusions, symptoms of schizophrenia also include unusual thoughts, confused speech, physical agitation, social withdrawal, and concentration difficulties. The DSM-V provides some criteria for drug-induced psychosis that help differentiate it from the diagnosis of schizophrenia. One of the criteria states that the symptoms cannot be explained by another psychotic disorder, such as schizophrenia or bipolar disorder. Also, there must be evidence that the symptoms of psychosis began during substance abuse even though, delusions and hallucinations persist when sober. Lastly, it must cause distress to the patient in order for it to be diagnosed as drug-induced psychosis.
Drug-induced psychosis, on the other hand, is often shown by symptoms of visual hallucinations and delusions. Typically, schizophrenia is a lifelong disorder, most often treatable with antipsychotic medication. Drug-induced psychosis can last days, months, or years, even into sobriety.
One specific form of drug-induced psychosis is cocaine-induced psychosis. A study done by Yilang Tang, Nancy L. Martin, and Robert O. Cotes, states that one-half to three-fourths of cocaine users experience psychosis. In this article, they provide a chart, comparing and contrasting cocaine-induced psychotic disorder (CIPD) and primary psychotic disorders. In CIPD, visual hallucinations are common, whereas in primary psychotic disorders, auditory hallucinations are seen more. Also, negative symptoms are more prominent in primary psychotic disorders.
Tang et al. also state that distinguishing CIPD from primary psychotic disorder is often difficult. Onset, quality of disorder, aggravating factors, and other symptoms must be carefully evaluated. The substance use history of the patient also must be determined in order to give a proper diagnosis.
There is still a lot of debate on whether or not drug use can cause schizophrenia or if it increases the risk for those who are genetically susceptible. There is also drug-induced psychosis that has symptoms that mirror schizophrenia symptoms. These symptoms can be exhibited for as long as years after drug use. The amount of the substance that was used may affect the course of CIPD.
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