Grant: Project Grant

Bipolar Disorder (BD) is a lifelong condition characterized by extreme mood fluctuations called manic and depressive episodes. BD affects approximately 2 in 100 people worldwide and has a significant impact on both the personal lives of patients and society. The rate of death by suicide among patients with BD is 20-30 times higher than of the general population and suicide attempts most commonly occur during depressive phases. Depression is responsible for most of the disability experienced by BD patients who spend a great amount of time in this phase. However, only two medications are approved by the Health Canada for treatment of the depressive phases of BD. Thus, developing new treatments that are effective and have a good safety profile is an urgent unmet need for people with BD. Cannabis sativa, also known as marijuana, has been used for millennia in various preparations and for different purposes. Among the more than 100 compounds present in the plant, cannabidiol is the substance with the more significant therapeutic potential: preliminary studies in humans have shown its medicinal properties in the treatment of epilepsy, anxiety and schizophrenia, and studies with mice have shown its properties in the treatment of depression. Furthermore, our preliminary study in bipolar depressed patients has shown that it is a safe medication with few adverse effects and that it likely has antidepressant effects. Considering the above, our objective is to test cannabidiol (CBD) as a treatment for the depressive phases of BD in a study design known as a randomized clinical trial. In this study we will divide the participants into two groups, one will receive daily capsules containing CBD, and the other will receive matching placebo capsules for 8 weeks. This will allow us to determine if improvement in depression is greater in the CBD group vs placebo group. It is noteworthy that all the participants will continue using their usual medication during the study.