Overall, most participating psychiatrists support further research and demonstrate a rather liberal attitude towards a possible legalization of CNMU. Regarding CMU, they acknowledge the lack of evidence but not necessarily a possible lack of effectiveness, and they differentiate between THC and CBD in terms of possible negative side effects.

Former surveys on attitudes towards CMU and legalization were population based or focused on different medical specialists and other expert groups (Chiu et al. 2022; Crowley et al. 2017; Oldfield et al. 2020). We focused for the first time on psychiatrists as the core professional expert group who regularly advise patients with cannabis-related mental health problems. Compared to the total pool of Swiss psychiatrists, our sample corresponds to the demographic age and sex distribution as indicated in the official statistics of Swiss psychiatrists (Giacometti-Bickel et al. 2013). Our sample had a higher proportion of subjects from German-speaking cantons and of psychiatrists working in an institution than in a private practice (Swiss Medical Association FMH 2021).

Concerning CNMU, we found that most of the participating psychiatrists, and especially those who were German speaking, would vote in favor of a legalization, given that effective health protection measurements would be accounted for. Our findings are in line with a Swiss population survey from 2021 on cannabis regulation, which found that the German part of Switzerland was more in favor of pilot studies for CNMU than the French parts (Bosshard et al. 2021). The latter finding may correspond to the situation in the neighboring countries, where Germany has a more liberal course towards CNMU regulation compared to France. Further, a greater part of our sample supports research on this topic, which could help to stimulate the discussion with skeptic voices, who oppose mainly because of the expected increase in mental health problems and the fear of being a gateway drug for other substance use disorders (Luca et al. 2017). Likewise, the official position statements of professional associations such as the American Psychiatric Association tended to express concern about the potential negative consequences of cannabis use (Position statement on need to monitor and assess the public health and safety consequences of legalizing marijuana [press release] 2022).

A possible legalization of CNMU raises the issue of diverse options for selling and distribution. Most of the Swiss psychiatrists in our study were in favor of the model of a state hemp store for the distribution of nonmedical cannabis. This state hemp store model represents ownership by state corresponding to the regulated legalization model, as it is realized in the state of Québec in Canada. Simultaneously, the psychiatrists clearly rejected the profit-oriented ultraliberal distribution of cannabis provided in certain US states (e.g., Colorado) (Payan et al. 2021).

Concerning possible regulations, the psychiatrists in our study preferred moderate cannabis regulation measures to prohibition and no regulation. These findings are in line with recent Swiss survey data of both cannabis users and nonusers of the general population conducted in an urban environment in Switzerland (Znoj et al. 2021). In contrast, a previous survey in 2007 assessed the attitudes of 82 Swiss psychiatrists on cannabis risks in psychiatric patients and found controversial opinions with rather categorical prohibitive or permissive positions (Zullino et al. 2008). The authors concluded that attitudes in psychiatrists resembled to those found in the population, indicative more of an ideological than empirical approach to the cannabis issue. We found the amount of active years as a variable that is associated with attitude towards cannabis regulation with older psychiatrists tending to agree for a more liberal approach. Interestingly, this finding contrasts with attitudes in the general population where younger people were more open to cannabis regulation and may reflect the professional and educational experience of the former with cannabis (Bosshard et al. 2021).

Likewise, the psychiatrists in our study showed a more liberal attitude compared to the survey data of Irish GPs, where the majority did not support a drug policy of cannabis decriminalization (Crowley et al. 2017). Also, the participating psychiatrists in our survey did not share the skepticism of surveyed addiction treatment specialists towards a regulative approach to distribute cannabis for CNMU (Ronne et al. 2021).

Members of our study group have also conducted a survey similar to the present in Swiss primary care physicians. Comparing both groups, psychiatrists seemed more liberal than the primary care physicians as the trend towards a legalization of CNMU was higher with 68% of psychiatrists compared to 56% of primary care physicians (Comazzi et al. 2022).

Regarding the use of cannabis for mental disorders, the rating of most of our psychiatrists corresponds to the scientific literature according to which evidence is too scarce to legitimate prescribing of cannabis for mental disorder (Black et al. 2019). Here, we found that those with more years of psychiatric experience, those working in an institution and those from a French canton are more skeptical than their counterparts. In contrast, psychiatrists answered that their reservation towards cannabis prescriptions for psychiatric conditions was not mainly due to an estimated lack of effect. Regarding this, our survey showed a significant difference between the respondents from the German-speaking part in contrast to those from the French-speaking parts with the latter being more skeptical about the effectiveness. This matches with our findings about attitudes towards legalization mentioned above. Interestingly, the participants in our study who work in an institution are more skeptical than those working in their own practice.

In terms of possible negative consequences of the consumption, participants rated that CBD might have a less negative impact on mental health than THC. The latter was rated to particularly worsen psychosis and memory, which is in line with the previous surveys with psychiatrists (Jacobs et al. 2019; Gage et al. 2016). There is one former survey, which asked Colombian psychiatrists about their knowledge and attitudes about cannabis in medicine. The latter agreed that insomnia and anxiety are mental health conditions, for which cannabis use might improve symptoms (Orjuela-Rojas et al. 2021).

About one-third of the psychiatrists felt rather insecure about providing counselling about CMU and had a strong interest in continuing education on this issue. These findings are in line with the attitudes of Australian psychiatrists being unsure of indications for cannabinoid prescription. The authors concluded that further education about CMU seem to be necessary (Jacobs et al. 2019). More than half of the psychiatrists stated that they had already been asked by patients to initiate treatment with CMU. Additionally, a small group of participants recommended cannabis self-medication or prescribed cannabis for mental health to their patients. This attitude corresponds to an increasing interest and belief of patients and the public in the use of cannabis to treat mental health-related problems (Gilman et al. 2022).

Our study has several limitations. Firstly, the surveyed psychiatrists were not a representative sample of all Swiss psychiatrists. Referring to the statistics of the Swiss Medical Association (Foederatio Medicorum Helveticorum; FMH) in 2021, there have been 3930 board-certified psychiatrists in Switzerland (Swiss Medical Association FMH 2021). Therefore, the 185 respondents from most Swiss cantons represent about 4.7% of all Swiss psychiatrists.

Secondly, since we only achieved a response rate of 13.8%, the sample may be considered a selected group of psychiatrists potentially biased, both towards a more negative or a more positive attitude, regarding cannabis legalization and medical use in psychiatry. Also, we did not conduct a sample size estimation so that the power of our statistical analyses is unknown. Our survey sample is representative for age and sex but does not completely match with the Swiss pool of all psychiatrists for language region or setting, and therefore, findings related to these two variables might be not representative for the population of Swiss psychiatrists. Especially, we have not considered the Italian- and Romansh-speaking psychiatrists as representatives of the two other Swiss national languages. Further, as it was possible for the participants to drop out of the survey before finishing and it was possible to skip questions, there might be a loss of information in either direction. At last, these findings cannot be generalized to other countries in Europe, America, or elsewhere as access to cannabis, practice of prescription, and legal frameworks substantially differ between countries.