Cannabis is harmful after the first episode of schizophrenia

Cannabis use is likely to cause schizophrenia in people at risk. According to one study, cannabis also drastically increases relapses after a first episode of schizophrenia.

This is the conclusion of an ongoing study with the participation of experts from the Innsbruck University Hospital. “In patients in remission after a first episode of schizophrenia, schizophreniform or schizoaffective disorders, cannabis use increases the frequency of relapses (…),” the authors wrote in the “Schizophrenia Bulletin.” This applies both to patients who follow treatment recommendations and use antipsychotics and to those who do not.

The international group of scientists, led by Linda Levi of the Sheba Medical Center in Ramat Gan in Israel, analyzed data from a European study on the first episodes of schizophrenic disorders. The treatment results were generally good.

The scientists write, “After ten weeks of antipsychotic treatment, 282 of 446 patients (63 percent) met criteria for remission (…).” Of the patients without symptoms, 134 could be followed for a year. Among other things, the experts analyzed the temporal relationship between cannabis use and signs of illness or relapse from different angles.

A clear effect of the use of narcotics was found. Compared to patients who did not use cannabis, those who used cannabis showed a 3.03 times higher risk of recurrence. Even in patients who regularly used their antipsychotics, the risk of recurrence was 2.89 times higher. The antipsychotics could therefore not compensate for the cannabis effect.

What the scientists highlight in their summary: The time relationship showed that cannabis use always preceded a relapse. The use did not emerge until the relapse was already underway.

It has long been known that frequent cannabis consumption can cause psychotic illnesses, especially schizophrenia. (aeg/sda/apa)