Schizophrenia linked to marijuana use disorder is on the rise, study finds

Schizophrenia linked to marijuana use disorder is on the rise, study finds

 

The proportion of schizophrenia cases linked with problematic use of marijuana has increased over the past 25 years, according to a new study from Denmark.   In 1995, 2% of schizophrenia diagnoses in the country were associated with cannabis use disorder. In 2000, it increased to about 4%. Since 2010, that figure has increased to 8%, the study found.   "I think it is highly important to use both our study and other studies to highlight and emphasize that cannabis use is not harmless," said Carsten Hjorthøj, an associate professor at the Copenhagen Research Center for Mental Health and an author of the study published in the medical journal JAMA Psychiatry.   The new study was based on data from Denmark's national health registry and included all people in Denmark born before December 31, 2000, who were 16 years or older at some point between January 1, 1972 and December 31, 2016.   Previous research has suggested that the risk of schizophrenia is heightened for people who use cannabis, and the association is particularly driven by heavy use of the drug. Many researchers hypothesize that cannabis use may be a "component cause," which interacts with other risk factors, to cause the condition.   While one study has suggested that schizophrenia is increasing in Denmark, in other countries the picture is uncertain, said Hjorthøj. In the US, the National Institute of Mental Health said it's hard to obtain accurate estimates of the prevalence of schizophrenia because diagnosis is complex and it overlaps with other disorders.