Association of Naturalistic Administration of Cannabis Flower and Concentrates With Intoxication and Impairment

Abstract

IMPORTANCEThe rapidly growing legal cannabis market includes new and highly potent products, the effects of which, to our knowledge, have not previously been examined in biobehavioral research studies because of federal restrictions on cannabis research. OBJECTIVE To use federally compatible, observational methods to study high-Δ9tetrahydrocannabinol (THC) legal market forms of cannabis. DESIGN, SETTING, AND PARTICIPANTSIn this cohort study with a between-groups design that was conducted in a community and university setting, cannabis flower users and concentrate users were randomly assigned to higher-vs lower-THC products within user groups. Participants completed a baseline and an experimental mobile laboratory assessment that included 3 points: before, immediately after, and 1 hour after ad libitum legal market flower and concentrate use. Of the 133 individuals enrolled and assessed, 55 regular flower cannabis users (41.4%) and 66 regular concentrate cannabis users (49.6%) complied with the study's cannabis use instructions and had complete data across primary outcomes.EXPOSURES Flower users were randomly assigned to use either 16% or 24% THC flower and concentrate users were randomly assigned to use either 70% or 90% THC concentrate that they purchased from a dispensary. MAIN OUTCOMES AND MEASURESPrimary outcome measures included plasma cannabinoids, subjective drug intoxication, and neurobehavioral tasks testing attention, memory, inhibitory control, and balance. RESULTS A total of 121 participants completed the study for analysis: 55 flower users (mean [SD] age, 28.8 [8.1] years; 25 women [46%]) and 66 concentrate users (mean [SD] age, 28.3 [10.4] years; 30 women [45%]). Concentrate users compared with flower users exhibited higher plasma THC levels and 11-hydroxyΔ 9 -THC (THC's active metabolite) across all points. After ad libitum cannabis administration, mean plasma THC levels were 0.32 (SE = 0.43) μg/mL in concentrate users (to convert to millimoles per liter, multiply by 3.18) and 0.14 (SE = 0.16) μg/mL in flower users. Most neurobehavioral measures were not altered by short-term cannabis consumption. However, delayed verbal memory (F 1,203 = 32.31; P < .001) and balance function (F 1,203 = 18.88; P < .001) were impaired after use. Differing outcomes for the type of product (flower vs concentrate) or potency within products were not observed. CONCLUSIONS AND RELEVANCEThis study provides information about the association of pharmacological and neurobehavioral outcomes with legal market cannabis. Short-term use of concentrates was associated with higher levels of THC exposure. Across forms of cannabis and potencies, users' domains of verbal memory and proprioception-focused postural stability were primarily associated with THC administration.

Effects of High-Potency Cannabis on Psychomotor Performance in Frequent Cannabis Users

“…In our group's recent study among individuals who were frequent users of legal market flower and concentrated cannabis, we demonstrated that these participants showed tolerance such that acute cannabis use did not impact many cognitive tasks (e.g., inhibitory control and working memory). However, balance performance emerged as one psychomotor function that is impaired after acute use but appears to recover within 1 h. 22 These findings are among the only data on the acute cognitive and psychomotor effects of legal market forms of cannabis among regular users and need to be explored further using additional tasks and in other populations. Taken together, the existing literature underscores the importance of gaining a better understanding of the extent and time course of the effects of various cannabis preparations and THC concentrations on psychomotor tasks, balance, and cognition, all of which may adversely affect driving ability.…”

Acute effects of naturalistic THC vs. CBD use on recognition memory: a preliminary study

“…The only other verbal memory test included was the International Shopping List Task (ISLT), which used different words than the recognition task. Our larger study found that THC administration was negatively associated with ISLT performance, but CBD results await ongoing data collection and analysis (Bidwell et al 2020). 2 We do not have the specific time point for the memory assessment for each participant, so the time given here is an estimate based on the general flow of the protocol.…”

“…Second, the 50 min that elapsed after consumption prior to the memory assessment (which occurred~35 min after blood draw to assess peak cannabinoid levels) may have limited the observed effects of THC and CBD. On the other hand, we have found the effects of THC on verbal recall memory to be relatively persistent when international shopping list test (ISLT) performance was compared between 15 and 30 min after use versus 60-75 min after use (Bidwell et al 2020). Third, given the nature of this observational pilot study we were not powered to include all relevant covariates or ethically able to match the groups on important characteristics such as cannabis use history, preferred form of cannabis (e.g.…”

“…Before leaving the baseline appointment, each participant was given a card with directions to a local dispensary in order to purchase their study product. Several strains of flower and two concentrates were used and randomly assigned in the larger studies (details on these procedures are in Bidwell et al (2020)). In order to achieve a wide range of THC and CBD exposure for the purposes of this verbal recognition feasibility study, individuals were assigned to the full range of strains being tested in the parent studies and each strain was grouped into one of the following categories for the purposes of this feasibility study: THC or THC + CBD (see Table 1).…”

“…The two studies were otherwise identical regarding the tasks that subjects completed. The detailed procedures and primary outcomes of these larger studies are described and reported elsewhere (Bidwell et al 2020). A recognition memory task, which was not part of the original aims of either study, was selected to extend our previous ISLT results (Bidwell et al 2018) beyond free recall with a task that provides better control over memory retrieval conditions (Kahana 2012).…”