Results presented here suggest a similar attenuation of oxidative stress markers in physically active marijuana smokers. Perhaps routine exercise can prove beneficial to protect against ROS production from marijuana smoking. Larger, longer term studies are needed to confirm this hypothesis,in particular involving a control group of inactive marijuana smokers.Considering the above, it is not surprising given our subject sample that differences between the smokers and non-smokers were not apparent. Prior studies focused on marijuana smokers have noted increased oxidative stress markers in self-reported marijuana smokers. For instance, alveolar macrophages isolated from marijuana smokers displayed lower intracellular GSH levels . Moreover,marijuana smokers reportedly exhibited increased levels of MDA with lower blood GSH and total antioxidant capacity, though this study made no mention of participant exercise status .
This discrepancy in our data from previously reported data is likely attributed to the beneficial adaptations to chronic exercise.In addition to protective effects of exercise against oxidative stress, it may protect cardio-metabolic parameters as well. Previous reports suggest marijuana smokers have increased systolic and diastolic blood pressure,with reduced high density lipoprotein-cholesterol. Regular participation in aerobic and resistan cetraining can result in a lowering of SBP and DBP, which may suggest why blood pressure differences were not observed in our physically active marijuana smokers. Though we did not measure HDL-C, it would have been interesting to see if our active marijuana smokers had any reduction in HDL-C, considering the expected increase with regular exercise .Related to the above findings, it is important to mention the limitations of our study. First, subjects were only required to have smoked marijuana for a minimum of three months prior to participating in this study. It is possible that long-term use of marijuana may have resulted in differing findings. Second, we only measured two commonly used biomarkers of oxidative stress and did so in blood samples.
It is possible that different findings could have been observed if other biomarkers were included and/or if we had used other tissue. Third, since we did not provide the marijuana directly to subjects, it is possible that the potency of the plant varied from person to person and from use to use.Fourth, while we included physical active subjects in this study, we did not have sedentary individuals acting as controls. This should be considered in future studies, as many marijuana smokers may be sedentary and this behavior may lead to differing results as compared to what was observed in the present study.Clearly, the above limitations need to be considered, as the findings of the present study should not suggest that marijuana smoking can be done without harm. There exists multiple papers documenting the concerns of marijuana use,the first of which may be “marijuana use disorder” for which approximately 30% of users meet criteria, as defined by the Diagnostic and Statistical Manual of Mental Disorders .
Moreover, users of marijuana, in particular heavy users,are more likely to have problems with use of alcohol and other drugs . It has been demonstrated that acute marijuana smoking impairs driving performance, with an increase in motor vehicle fatalities linked to marijuana legalization. Both short-term and long-term use can lead to cognitive performance decline. Individuals should consider these facts and utilize the data presented in this study only in the context of the “big picture”. Recent studies have shown that the prevalence of marijuana use increased in the United States over the past decade. Among young adults, aged 18 – 29, the percentage reporting past-year marijuana increased from 17.7% in 2005 to 29.2%in 2015 . Although the prevalence of use has remained steady among high school students, annual marijuana use among college students reached a level not seen since the late 1980s . The prevalence of depressive disorders has also been on the rise in the United States . Past month prevalence among adults was about 10% in 2017 ,which is substantially higher than in 2002. The prevalence of major depressive disorders increased from 8.7% in 2005 to 11.3% in 2014 among adolescents, aged 12 – 17, and from 8.8% to 9.6% among young adults, aged 18 -25 .
These coincident trends among young people are likely due to a host of structural,demographic, social, and psychological factors. Nonetheless, research has shown that there is a consistent individual-level association between marijuana use and depressive symptomatology. It is not clear, though, whether this association is causal in nature or due to confounding factors. Studies have provided evidence in support of several hypotheses, including that factors such as personal and interpersonal stressors affect the probability of both marijuana use and depressive symptoms ; that more frequent marijuana use increases the risk of depressive symptoms; and that young people initiate or increase marijuana use following the onset or rise of depressive symptoms.