As a reminder, for the purposes of this dissertation, motives were conceptualized as cognitive explanations for a behavior that provides insight into the context and circumstances of a behavior . However, in line with Cooper’s Motivational Model of Alcohol Use which is based on Cox and Klinger’s model , use of alcohol and/or other drug is motivated by certain valued outcomes. Taken together, the seventeen motives of use generated by the confirmatory factor analyses fit one but not both conceptualization of motives. Some of the motives only provide insight into the context and circumstances of a behavior, and do not say anything about the valued outcomes or incentive or desired end state for use . It can however, be argued that, although these motives may not fit Cooper and Cox and Klinger’s conceptualization that motives should give insight into the desired end state or valued outcomes an individual wishes to achieve, they do provide us with contextual and circumstantial insights for a behavior, which is relevant in understanding why individuals use and were therefore be retained as motives of marijuana use. As an example, the motive of availability is composed of the following items: because it is there, because you can get it for free, and because it is readily available. Although this motive of use does not ascertain anything about the valued outcome or desired end state one wishes to achieve through use,vertical grow racks it gives us insight into the context and circumstances of use. This also applies to the motives of relative low risk and alcohol.
Whereas previous work had relied on instruments which did not include medical motives of marijuana use, nor had been validated in a diverse sample of young adults who use marijuana with regards to education and use , work presented in this thesis establishes the validity of a motive of marijuana use scale which combines both recreational and medical motives of use. This is significant as, as previously documented, although young adults who use marijuana may identify their use as either medical or recreational, there is a significant overlap in use. Recently, Lee’s twelve motives of marijuana use have also been confirmed in a sample of medical cannabis patients who were twenty-one years or older . This further confirms that young adults who report using marijuana for medical reasons also use for non-medical reasons and validates the need for a scale that contains both recreational and medical motives of use. The work in this first aim builds on and extends work done by Simmons et al. and Lee et al. on motives of marijuana use as it: 1) validates the factor structure of existing motives of marijuana use in a new population; 2) establishes new motives of marijuana use that pertain specifically to medical use, and 3) confirms that neither medical nor non-medical motives of use differ by gender. This therefore means that the amended Comprehensive Marijuana Motives scale is stable over time and can be used indiscriminately for both men and women. Furthermore, it also implies that for any given motive on that scale, the motive is conceptually the same for both men and women. Given the evolving context of marijuana legalization, this study contributes to laying the groundwork for the study of motives of marijuana use and medical motives of marijuana use.
These findings indicate that there are key, non-overlapping, non-gender specific recreational and medical reasons that drive use in a sample composed of young adults who use marijuana for medical and/or recreational reasons. These findings reinforce the notion that marijuana use is motivated by differing needs, offering insight into the circumstances in which an individual uses marijuana. The amended questionnaire, can therefore be used for ensuing analyses in our sample of young adults who use marijuana, regardless of how they identify their use. However, to use this amended questionnaire with confidence in any group of young adults who use marijuana, it would need to be further validated using a random sample of young adults who use marijuana. Ensuing work in this dissertation focused on investigating whether motives that drive use give rise to distinct use behaviors and whether these distinct use behaviors driven by specific motives may be differentially associated with mental health outcomes, while accounting for gender. The outcomes, namely symptoms of depression, symptoms of anxiety, and overall psychological distress are all important precursors of diagnoses of depression and anxiety, thus providing insight into opportunities for interventions to ensure a successful transition from adolescence to adulthood for marijuana using young adults. To our knowledge, this is the first study that focuses on motives of marijuana use and mental health outcomes of young adults who use marijuana in a context of facilitated access to marijuana. This is significant as the decreasing perceptions of risks associated with marijuana use and the increase in marijuana use, especially in young adults in a context where marijuana is easily accessible, creates a perfect storm that might interfere with assuming the roles and responsibilities of adulthood.
Understanding these associations provides us with tools to develop potentially helpful interventions to help enable progression to adulthood by targeting specific motives of use. As demonstrated by Blevins et al. motives of use are amenable to change, and changes in motives of use can engender changes in use patterns which can then result in changes in associated outcomes. Findings from this dissertation indicate that, as previously demonstrated in the alcohol and marijuana literature, coping motivated use is associated with poor outcomes. This suggests that focusing prevention and intervention strategies on developing adaptive coping mechanisms may be an avenue to improve the mental health of young adults who use marijuana to cope. Furthermore, the findings also ascertain that gender specific interventions with regards to the social anxiety motive of use are also necessary. Although these results generally replicate and extend our understanding of the associations between motives of marijuana use and symptoms of depression, symptoms of anxiety, and psychological distress there are, as with any research endeavor, a few limitations to this work that should not outweigh its strength. Limitations. First, although targeted sampling and chain referral sampling are two recruitment methods that have proven to be successful to recruit hard to reach populations , they generate non-random samples and thus, our findings are not generalizable. We are also not able to evaluate the potential of sampling bias because there is no population-level data available on the target population. However, this is the first study to include a sizeable sample of young adults who use marijuana for medical reasons as well as detailed questions about their motives of use. Second, there are limitations of reporting biases. Participants may have unwillingly, due to recall bias or to social desirability bias,indoor grow light shelves under reported or misreported things such as motives of use, frequency of use, severity of dependence, mental health history, mental health symptoms, and other drugs used. Third, a minimum sample size of 200 is usually recommended to obtain appropriate statistical power when employing confirmatory factor analysis . Our sample included 240 men and 124 women. Although the male sample size was sufficient for our analyses, the female sample size was smaller than recommended. This may have led to Type 2 error in testing moderation. Fourth, it is usually not recommended to run a confirmatory factor analysis on the same sample that was used to conduct an exploratory factor analysis. However, it was possible to replicate the findings from the confirmatory factor analysis using wave 2 data. This allowed the ability to demonstrate the stability of the factors generated using Wave 1 data. Fifth, given the number of motives of use tested as independent variables, in concordance with the sample size, there are potential issues with Type I errors or false positive findings. As such, great care was taken to limit the number of additional variables to be entered in the model to minimize the number of comparisons being made as, in multiple linear regressions, the likelihood of Type I errors increases with the number of comparisons made. Thus, the more variables in a model, the more comparisons are made.
Therefore, control variables were limited to age, sex, user group, and race/ethnicity. Furthermore, to assess significance of the multiple linear regression associations, a Bonferroni corrected p value of 0.003 was used. Although useful to reduce potential Type I errors, Bonferroni corrections are at times considered to be overly conservative. It is therefore possible, that in our attempt to prevent Type I error, Type II errors occurred and findings that should have been identified as significant were not. Finally, with regards to limitations, this study is limited by the availability and appropriateness of the available variables. For instance, past 90 days marijuana use and daily number of hits were used to operationalize frequency of use. Although these two variables do give insight into how often an individual uses, it says little, if nothing about how incapacitated they are from this use. For instance, an individual may use once a day every day and be able to carry on with daily activities, versus someone who may only use forty-five out of ninety days, but uses heavily in these forty-five days to the point of not being able to carry on with daily activities. As such, a variable that would operationalize intoxication and/or use and interference with daily activities may be more appropriate to assess as a mediator for use. In the same vein, strain and concentration of cannabis used were not available for these analyses. Given the difference in the composition of products available as well as the resulting intoxication , there may be potential differences in associated mental health outcomes. Hypothetically, the differences could be due to the presence and concentration of ∆9 – tetrahydrocannabinol , the psychoactive compound in cannabis as Cannabidiol , on the other hand is non-psychoactive. Understanding how different compounds are tied to mental health outcomes may be more relevant than understanding whether or how the user group plays a role in the associations between motives of marijuana use and mental health outcomes. Strengths. Despite these limitations, the work presented in this dissertation advances the knowledge about the influence of motives of marijuana use on mental health outcomes in a sample of young adults who use marijuana for medical and/or recreational reasons. Of note, is the fact that the sample is composed of individuals residing in the Los Angeles Metro area. This is significant because marijuana, even if only for medical purposes, has been legal in California since 1996. This means that the participants in this sample may have less reservation and be less inclined to social desirability bias with regards to marijuana use than participants who might have not been recruited in an area with a long history of marijuana, in some form, being legal. This may also be true because part of the sample use for medical reasons and therefore feel their use is legitimate and not an illegal behavior. Furthermore, the amended Comprehensive Marijuana Motives Questionnaire was validated and tested for measurement in variance both by gender and across time. This means that: 1) existing motives of use might be useful for studying recreational and medical marijuana use, although it is cautioned again that the sample is not representative; 2) attention, pain, nausea, substitution, and natural remedy can be used when studying medical motives of use; 3) this amended questionnaire and resulting motives are applicable to both men and women; and 4) motives of marijuana use are stable across time. Finally, with regards to strengths, the outcomes of interest in this dissertation are symptoms of depression and symptoms of anxiety. Although this may seem less interesting or exciting to study than actual diagnoses of depression and anxiety, it provides both researchers and practitioners with valuable information that can help inform intervention efforts to reduce such distress and prevent reliance on the drug for future mood regulation . It also provides valuable, gender specific, information for pre-diagnosis intervention and what may exacerbate symptoms.Although there is much that remains to be elucidated about motives of marijuana use and the associations between motives of marijuana use and mental health outcomes in young adults, results presented in this dissertation contribute to the literature by starting to close some of the literature gaps identified in the introduction of this dissertation.