Response to Canadian Psychiatric Association Cannabinoid Products Position Statement: Potential for Ameliorating Cannabis Withdrawal

Despite common perceptions that cannabis is safe, there is mounting evidence to support an association between cannabis use and several neuropsychiatric sequelae. The recently published Canadian Psychiatric Association position statement provides a timely review of the evidence for cannabinoid products in treating various psychiatric disorders.¹ Dr. Tibbo and colleagues proceed to make several evidence-based recommendations concerning anxiety, eating, mood, neurodevelopmental, trauma-related, schizophrenia-spectrum, and substance use disorders.¹ While the position statement is by no means an exhaustive review, there are opportunities to further boost its impact.

First, there is some very preliminary evidence for cannabinoid products to treat neuropsychiatric symptoms of dementia.² In this context, however, cannabinoids can further impair (certain aspects of) cognitive function in patients with dementia.

Second, the issue of cannabis withdrawal syndrome (CWS) deserves additional attention. CWS, recently adopted by the DSM-5, requires the presence of at least three of the following symptoms developing within 7 days of reduced cannabis use: (i) irritability, anger, or aggression; (ii) nervousness or anxiety; (iii) sleep disturbance; (iv) appetite or weight disturbance; (v) restlessness; (vi) depressed mood; and (vii) somatic symptoms such as headaches, sweating, nausea, vomiting, or abdominal pain. CWS impacts approximately half of all cannabis consumers.³ CWS, when left untreated, may drive ongoing cannabis use and diminish successful efforts to cut down or cease cannabis use. To that end, there has been some interest in prescribing cannabinoids to reduce CWS and cannabis use, in parallel to the treatment of opioid withdrawal and reducing illicit opioid use. Several of the cited studies, including Allsop et al. 2014, Haney et al. 2013, and Levin et al. 2011, demonstrated that some cannabinoids—when combined with psychotherapy—could alleviate CWS and reduce cannabis use. Psychiatrists should be aware of the high prevalence of CWS to counsel patients and support individuals who are reducing their use of cannabis.

Finally, it is essential to highlight the differing pharmacokinetics and pharmacodynamic profiles of various cannabinoid preparations across the extant studies. For example, cannabidiol (CBD) is a primary cannabinoid with a complex mechanism of action involving the cannabinoid CB₁ and CB₂ receptors. Compared to tetrahydrocannabinol (THC), CBD has a reduced capacity for causing intoxication and may even lessen THC’s adverse effects at high doses.⁴ Given these differences, we should not conflate these agents or evidence for their application in various psychiatric illnesses. For example, the first randomized clinical trial of CBD for Cannabis Use Disorder (CUD) found that doses of 400 to 800 mg were safe and more efficacious than placebo at reducing cannabis use.⁵ While CBD is also under investigation as a treatment for several other neurological and psychiatric disorders, it remains an off-label treatment given the limited high-quality evidence for any particular condition.

In conclusion, the position statement is an excellent summary of the extant literature on cannabinoids as mental illness treatments. However, there is also some evidence of the therapeutic potential for cannabinoids in treating dementia, CWS, and CUD, which are undoubtedly relevant given the scarcity of evidence-based treatments for these conditions.