The centre-right alliance in Germany tipped to lead the next administration in Berlin is likely to look at reforming or even reversing a law legalising cannabis for personal use in the country – with a senior spokesman citing results of a major new study from Canada which showed alarming increases in psychosis after legalisation there.
The Christian Democratic Union (CDU) and the Christian Social Union (CSU) – a sister party based in Bavaria have campaigned to reverse the law regulating the sale and consumption of cannabis. The CDU/CSU are currently in negotiations with the SPD for a programme for government.
“We will do everything we can to stop the negative effects of cannabis legalization, to fight drug-related crime and to strengthen the protection of minors,” CDU legal policy expert Günter Krings told news agency dpa previously.
Tino Sorge, the CDU/CSU parliamentary spokesman on health policy issues, argues that the cannabis law – permitting adults to possess up to 25 grams of cannabis and grow three plants per household – introduced by the previous coalition, which included the SPD, is “a dangerous mistake” and must be “reversed”.
The CDU’s leader Friedrich Merz’s claimed the new policies, which have been in effect for less than a year, have led to an increase in drug-related crime. CDU spokespersons say they agree that the use of medical marijuana should remain legal.
While smoking cannabis is banned in schools, sports facilities and within 100 metres of other public spaces, it permits the formation of non-commercial “growers’ groups”, allowing up to 500 adult living in Germany to grow cannabis collectively and supply it to each other for personal use, with a maximum of 50 grams per member per month.
Sorge pointed to results of a major new study from Canada which showed an alarming increase in psychosis after cannabis was legalised there, saying the results should not be ignored.
The study, Changes in Incident Schizophrenia Diagnoses Associated With Cannabis Use Disorder After Cannabis Legalization, published last month on Jama Open Network, linked rising cases of psychosis and schizophrenia in Canada to Cannabis Use Disorder (CUD) since the country legalized marijuana for recreational use in 2018.
Researchers said the population-based cohort study, which included more than 13.5 million people, sought to examine if the liberalization of medical cannabis and the legalization of nonmedical cannabis in Canada was associated with changes in the proportion of cannabis use disorders associated with schizophrenia.
They found that cannabis use disorder associated with schizophrenia increased significantly from 3.7% in the prelegalization period to 10.3% during the postlegalization period.
“These findings suggest that the association between cannabis use disorders and schizophrenia is an important consideration for the legalization of cannabis,” they cautioned.
In the study of individuals aged 14 to 65 years in Ontario, Canada, “the proportion of incident cases of schizophrenia associated with CUD almost tripled during a period of substantial liberalization of cannabis policy. Ongoing research is indicated to understand the long-term associations of cannabis policy with the prevalence of psychotic disorders,” they added.
The researchers said they suspect CUD is even more widespread than the data indicate. “Our estimate is that for every person treated for C.U.D. there are another three who didn’t seek care,” lead author Dr. Daniel Myran, an assistant professor of family medicine at University of Ottawa, told The New York Times. “So this is not just CUD, but bad enough that they sought care for it.”
Another study from the same researchers analyzed Ontario health records from 106,994 people diagnosed with CUD during a hospital or emergency room visit between 2006 and 2021, and found:
- 3.5% of people with CUD died within five years of treatment, compared to 0.6% of a similar group of people without CUD.
- CUD patients still had a 2.8 times higher risk of death than the general population even after other risk factors like mental illness, heart disease, cancer and other substance use were considered.
- Young adults aged 25 to 44 faced the highest risk of premature death.
Researchers looked at three periods: 2006–2015 (before cannabis legalization); 2015–2018 (amid widening use of medical and non-medical cannabis); and 2018–2022 (after legalization), and examined rates of psychosis and schizophrenia.
While the overall rate of schizophrenia remained stable, researchers found that:
The percentage of cases linked to CUD jumped from 3.7% to 10.3% after legalization, the rate of psychosis (without schizophrenia) nearly doubled, and young adults aged 19 to 24 were most affected.
“This is a period of the life span when the brain is still developing and still vulnerable to the effects of cannabis,” Jodi Gilman, an associate professor of psychiatry at Harvard Medical School who wrote a commentary about the study, told The Times. Psychosis and schizophrenia are also known to develop in young adulthood, Gilman added, “so you have a double hit.”
The authors of the study said that the study had several limitations, including the lack of access to several important potential confounders, including individual-level income, educational attainment, family history of mental health disorders, and genetics.
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