Cannabidiol for people with schizophrenia

Abstract

Schizophrenia is a severe mental health condition that often leads to disability; has direct implications on level of functioning, autonomy and well‐being; and decreases quality of life (Solanki 2008). Because of the complex nature of this disorder, finding safe and effective treatments is a challenge (Rogers 2009). Available treatments for schizophrenia are ineffective in many people and are associated with serious adverse effects (Patel 2014). The discovery of the endocannabinoid system in relation to the psychotic components of mental illness has motivated research into the use of CBD as an alternative or add‐on for treating schizophrenia (Leweke 2012; Cohen 2019).

Three previous systematic reviews have assessed the effects of CBD in people with schizophrenia. McLoughlin 2014 identified only one eligible study, but reports of other relevant studies have been published since. Ahmed 2021 aimed to summarise the results of controlled trials using defined doses of THC and CBD in schizophrenia; it included evidence from clinical trials and one case series. Finally, McKee 2021 aimed to aggregate the high‐level evidence on the effectiveness of cannabinoid products for treating psychiatric disorders (including schizophrenia) in adults. In Ahmed 2021 and McKee 2021, the available evidence was limited and heterogeneity was substantial. This review aims to identify the available evidence on the effectiveness and safety of CBD for treating people with schizophrenia.