The patient is a 30-year-old male who was born in Turkey and is of Kurdish descent. He moved to Switzerland in 2009 at the age of 19. In 2010, he married a Swiss woman with whom he has one child. They divorced in 2016 and he has been living alone in a rented apartment since.

He first presented in our outpatient clinic at the age of 22 in late 2012. He reported that he had lost his driving license due to cocaine use while driving and that the relationship with his wife had ended. At this time, he was unemployed, smoked cannabis 2-3 times a week and used alcohol regularly. The Beck depression inventory (BDI) showed a moderate depression with a score of 26. Over the following years, he was hospitalized 30 times in our clinic, voluntarily as well as involuntarily (see Table 1). He was diagnosed with cannabis use disorder (2014), mixed personality disorder with narcissistic and antisocial traits (2015), cocaine use disorder (2016) and schizophrenia (2018) according to ICD-10.

He first admitted himself to our clinic in 2014. He wished to cease cannabis consumption (about five joints a day) and reported depressive symptoms. In 2015 he was incarcerated for criminal assault. During his imprisonment, he committed a suicide attempt (self-administered lacerations at his neck and sternum). Consequently, the patient was admitted to a psychiatric forensic department, where he removed a lightning bulb in the isolation room and injured himself on the left wrist. In 2016, at the age of 25, he reported to suffer from acoustic hallucinations for the first time (imperative voices telling him to consume drugs) and that he had experienced these symptoms for 4 years. It was unclear whether this first documented psychotic episode was caused by substance use alone and he did not meet the criteria for paranoid schizophrenia according to ICD-10 at the time. During treatment, he stated that the use of cannabis would positively affect his hallucinations. He also reported to gamble a lot, losing up to CHF 9,000 in a single month. Additionally, he repeatedly expressed suicidal thoughts, like the idea of ending his life with a drug overdose. From 2016 onwards, he continued to admit himself or was referred to our clinic through his practicing psychiatrist. He alternately presented psychotic and depressive symptoms, besides the wish for detoxification and withdrawal-treatment due to continued heavy cocaine (1–2 g/day), alcohol (5–8 liters beer/day), and cannabis (3–5 joints/day) use. In 2018, the psychotic symptoms persisted despite the patient's abstinence from cannabis and cocaine, hence the diagnosis of paranoid schizophrenia was made. Due to the severity of his psychotic symptoms inpatient treatments focused on psychoeducation and the establishment of pharmacotherapy with atypical antipsychotics. In between these hospitalizations, the patient repeatedly stopped his medication (see Table 2) and resumed cannabis, cocaine, and alcohol use.

At the end of 2019, he was involuntarily committed after shouting and rampaging in public, attacking the arresting police officers, and smashing his head against the police station's wall. He was taken to the hospital, where he had to be sedated with propofol, as his head injury could not be examined otherwise. After that, he was transferred to our psychiatric clinic, where he stated that he could not remember the events that led to his committal. He reported that he had not used cocaine within the last few months but corrected himself after a toxicologic serum screening showed positive for cocaine, cannabis, and alcohol.

In May 2020, the patient wanted to admit himself to our clinic yet again. When he was told that an immediate inpatient admission was not possible at the time, he took 20 mg of lorazepam and 55 mg of aripiprazole presumably to force his admission. As sedation wore off, the patient became increasingly aggressive and eventually attacked and injured a staff member, which led to two police-assisted isolation. The next day he apologized for his actions but was subsequently banned from entering the clinic for a month for attacking and injuring a staff member.

In January 2021, he was involuntarily committed (29th hospitalization) after getting involved in a brawl. At this time, he was intoxicated, psychotic, and did not cooperate with our staff. Again, he had to be sedated with propofol as otherwise a cranial computer tomography to rule out head injuries would not have been possible. During his hospitalization, a knife with a blade length of 15 cm was found in his room by our staff. The confiscation led to aggressive behavior and threats from the patient, leading to another ban from our clinic.

In his most recent involuntary hospitalization (30th), the police reported that the patient went on a rampage, damaging cars in the city center. He was intoxicated (alcohol) but refused to give a urine sample for further toxicological examination. He was delusional and paranoid at the time of admission (fear of getting poisoned). Throughout the hospitalization, the patient started damaging the inventory of our department. An application for compulsory treatment authorization was granted as per article 434, Swiss civil code. After switching from oral olanzapine to oral aripiprazole, the patient agreed to an intramuscular depot medication with aripiprazole. However, he continued to use cocaine and cannabis during hospitalization. Therefore, after the patient gave his informed consent, methylphenidate 100 mg/d was prescribed off-label to support cocaine abstinence.

At the same time, we initiated treatment with CBD-rich cigarettes (Manufacturer: Koch & Gsell; Products: “Heimat” Pure Hemp, “Heimat” Tobacco+Hemp; approx. 10% of CBD, <1% of THC) as adjunctive inpatient therapy. A week later in the following therapeutic session, the patient stated that he could now also abstain from illicit cannabis use. He replaced his former habit of smoking cannabis joints (illicit cannabis and standard tobacco) with CBD-rich cigarettes (approx. 20 cigarettes per day, approx. 400 mg of CBD per day). Interestingly, the patient managed to reflect on his cannabis use and its negative impact on his schizophrenia for the first time. He began to realize the relation between worsening of psychotic symptoms and continued use of cannabis containing high THC contents. Additionally, he claimed that “street cannabis would destroy my therapy with aripiprazole.” He maintained cocaine and illicit cannabis abstinence until discharge from our ward. The urine test for cocaine showed a negative result at the time of discharge, 2 weeks after initiation of methylphenidate. THC showed positive as our tests were not able to distinguish between illicit cannabis and CBD-rich cigarette consumption. For the assessment of the patient's compliance regarding the cessation of illicit cannabis use, we relied on our clinical impression and self-reports.

We established a controlled daily dispense of methylphenidate and monthly intramuscular injections of aripiprazole (400 mg/28 days) via a local pharmacy. Once weekly psychotherapeutic outpatient contacts were scheduled, and he received weekly rations of CBD cigarettes. The cantonal social department approved to cover the costs of a CBD product for half a year. For financial reasons, we suggested the purchase of “Alplant Skywalker Lemon OG Outdoor, 50 grams” (CBD-rich hemp <7% CBD, <0.2% THC) which was used by the patient to roll his cigarettes. The patient receives a package of this product every week. He continues to appear regularly at the weekly outpatient appointments. Furthermore, he reported significantly reduced illegal cannabis use but admitted some relapses. When reflecting upon the cannabis use, he started to see the link between psychotic symptoms and substance use. Due to this realization, the patient now prefers CBD rather than ordinary cannabis. He refrained from using cocaine since establishing the off-label therapy with methylphenidate. A 6-week and a 12-week follow-up urine test resulted negative for cocaine. No further psychiatric hospitalization was required since discharge. Aided by our clinic's social workers, a supportive long-term therapeutic setting is now being planned. However, his psychotic symptoms (delusion and paranoia) did not completely remit.