Aims: Surprisingly little is known about the self-administration practices among patients using cannabis for medical purposes. Information is lacking on the diversity of products (e.g. combustible/edible), strength (e.g. THC, CBD), and dosage. Our best theoretical models are derived from animal studies, namely continuous reinforcement paradigms that identify variability in consumption. Yet, data are lacking on how well this paradigm parallels human behavior.
Methods: In 2014, medical cannabis patients (n = 50) were recruited in California (ages 18+) to complete a baseline survey and then a paper diary capturing specific product use and motivations for use throughout each day. Latent trajectory analysis was used to compare empirical subtypes to animal models of addiction.
Results: Five classes were extracted, two of which were stable dosing groups: one using multiple (5 or more) combustible products per day (10% of users) and another (15%) mixing in combustible products and vaporizers. Three classes, representing the majority of the sample, were characterized by variable dosing and product selection. Edibles were used rather infrequently (10% of the patients), largely as a means to consume in places where use is stigmatized. Income was the strongest predictor of trajectory classes (ORs 1.9–3.9) involving non-stable consumption. Qualitative interviews suggested that pay periods were important drivers of usage frequency, and additional analyses of the diary data showed frequency was highest in the 48 h period on dates commonly associated with pay periods, e.g., 48 h starting from the 1st to the 2nd of the month, 15th to the 16th of month. Approximately 25% of the events were used exclusively to self-treat pain, the rest being mixed (53%) or exclusively euphoria/relaxation (22%).
Conclusions: The ability to pay for cannabis appeared to a major driver of consumption among pain patients. The natural environment's role in consumption has important implications for testing animal models of addiction.
Financial support: NIDA R01 DA038427 PII Novak.