Psychiatric University Hospital, Research Group on Substance Use Disorders, Selnaustrasse 9, 8001 Zurich, Switzerland.
Harm Reduct J. 2010 Sep 28;7:22. doi: 10.1186/1477-7517-7-22.
There has been a considerable amount of debate among the research community whether cannabis use may cause schizophrenia and whether cannabis use of patients with schizophrenia is associated with earlier and more frequent relapses. Considering that studies exploring patients' view on controversial topics have contributed to our understanding of important clinical issues, it is surprising how little these views have been explored to add to our understanding of the link between cannabis and psychosis. The present study was designed to elucidate whether patients with schizophrenia who use cannabis believe that its use has caused their schizophrenia and to explore these patients other beliefs and perceptions about the effects of the drug.
We recruited ten consecutive patients fulfilling criteria for paranoid schizophrenia and for a harmful use of/dependence from cannabis (ICD-10 F20.0 + F12.1 or F12.2) from the in- and outpatient clinic of the Psychiatric University Hospital Zurich. They were interviewed using qualitative methodology. Furthermore, information on amount, frequency, and effects of use was obtained. A grounded theory approach to data analysis was taken to evaluate findings.
None of the patients described a causal link between the use of cannabis and their schizophrenia. Disease models included upbringing under difficult circumstances (5) or use of substances other than cannabis (e. g. hallucinogens, 3). Two patients gave other reasons. Four patients considered cannabis a therapeutic aid and reported that positive effects (reduction of anxiety and tension) prevailed over its possible disadvantages (exacerbation of positive symptoms).
Patients with schizophrenia did not establish a causal link between schizophrenia and the use of cannabis. We suggest that clinicians consider our findings in their work with patients suffering from these co-occurring disorders. Withholding treatment or excluding patients from certain treatment settings like day-care facilities or in patient care because of their use of cannabis, may cause additional harm to this already heavily burdened patient group.
在研究界，关于大麻使用是否会导致精神分裂症，以及精神分裂症患者使用大麻是否与更早、更频繁的复发有关，存在相当大的争议。考虑到探索患者对有争议话题的看法有助于我们理解重要的临床问题，令人惊讶的是，我们对这些观点的了解甚少，无法深入了解大麻与精神病之间的联系。本研究旨在阐明使用大麻的精神分裂症患者是否认为大麻的使用导致了他们的精神分裂症，并探讨这些患者对该药物影响的其他看法和认知。
我们从苏黎世大学精神病院的门诊和住院患者中招募了 10 名连续符合偏执型精神分裂症标准和大麻有害使用/依赖标准（ICD-10 F20.0 + F12.1 或 F12.2）的患者。我们采用定性方法对他们进行了访谈。此外，还获得了使用量、频率和效果的信息。采用扎根理论方法对数据进行分析。
没有患者描述大麻使用与精神分裂症之间存在因果关系。疾病模型包括困难环境下的成长（5 例）或使用除大麻以外的物质（例如致幻剂，3 例）。另外两名患者给出了其他原因。四名患者认为大麻是一种治疗辅助剂，并报告说积极的效果（减轻焦虑和紧张）超过了其可能的副作用（加重阳性症状）。
精神分裂症患者没有在精神分裂症和大麻使用之间建立因果关系。我们建议临床医生在治疗同时患有这些共病的患者时考虑我们的发现。因为患者使用大麻而拒绝治疗或将他们排除在某些治疗环境之外，如日间护理机构或住院治疗，可能会给这个已经负担沉重的患者群体带来额外的伤害。
