Medical Cannabis for the Management of Pain and Quality of Life in Chronic Pain Patients: A Prospective Observational Study.

OBJECTIVE: To evaluate the short-term and long-term effects of plant-based medical cannabis in a chronic pain population over the course of one year. DESIGN: A longitudinal, prospective, 12-month observational study. SETTING: Patients were recruited and treated at a clinic specializing in medical cannabis care from October 2015 to March 2019. SUBJECTS: A total of 751 chronic pain patients initiating medical cannabis treatment. METHODS: Study participants completed the Brief Pain Inventory and the 12-item Short Form Survey (SF-12), as well as surveys on opioid medication use and adverse events, at baseline and once a month for 12 months. RESULTS: Medical cannabis treatment was associated with improvements in pain severity and interference (P < 0.001) observed at one month and maintained over the 12-month observation period. Significant improvements were also observed in the SF-12 physical and mental health domains (P < 0.002) starting at three months. Significant decreases in headaches, fatigue, anxiety, and nausea were observed after initiation of treatment (P ≤ 0.002). In patients who reported opioid medication use at baseline, there were significant reductions in oral morphine equivalent doses (P < 0.0001), while correlates of pain were significantly improved by the end of the study observation period. CONCLUSIONS: Taken together, the findings of this study add to the cumulative evidence in support of plant-based medical cannabis as a safe and effective treatment option and potential opioid medication substitute or augmentation therapy for the management of symptoms and quality of life in chronic pain patients.

Performance on a probabilistic inference task in healthy subjects receiving ketamine compared with patients with schizophrenia.

Evidence suggests that some aspects of schizophrenia can be induced in healthy volunteers through acute administration of the non-competitive NMDA-receptor antagonist, ketamine. In probabilistic inference tasks, patients with schizophrenia have been shown to 'jump to conclusions' (JTC) when asked to make a decision. We aimed to test whether healthy participants receiving ketamine would adopt a JTC response pattern resembling that of patients. The paradigmatic task used to investigate JTC has been the 'urn' task, where participants are shown a sequence of beads drawn from one of two 'urns', each containing coloured beads in different proportions. Participants make a decision when they think they know the urn from which beads are being drawn. We compared performance on the urn task between controls receiving acute ketamine or placebo with that of patients with schizophrenia and another group of controls matched to the patient group. Patients were shown to exhibit a JTC response pattern relative to their matched controls, whereas JTC was not evident in controls receiving ketamine relative to placebo. Ketamine does not appear to promote JTC in healthy controls, suggesting that ketamine does not affect probabilistic inferences.