Introduction:Health benefits of marijuana use have been identified for several diseases such as glaucoma, cancer, HIV-AIDS, multiple sclerosis, and Crohn’s disease. In fact, more than 100 conditions qualify for medical marijuana in California. Conversely, only a few definitive negative health effects of marijuana have been found, including respiratory problems, cardiovascular risks, and cognitive impairments. Nevertheless, few studies have prospectively examined the long-term effects of marijuana use on physical health. Even rarer are studies examining race differences in these effects, which is critical given health disparities generally favoring Whites and generally higher rates of marijuana use among Black than White adults. The purpose of this study was to examine racial differences in the effects of chronic and intensive marijuana use during adolescence and/or emerging adulthood (ages 18-25) on physical health symptoms in young adulthood (age 35).
Methods: We used data from 487 young men who were interviewed annually from the 7thgrade until age 25 and then again at age 35. Four trajectory groups of regular (approximately monthly) marijuana use between ages 12 and 25 were identified: nonusers/nonregular users, adolescence-limited, late-onset, and chronic regular marijuana users.
Results: ANCOVAs (covarying race) and Chi-square tests indicated no trajectory group differences in the number of current health problems, number of medications currently taken for physical illnesses, number of physical injuries, ever being shot by age 35, and being hospitalized in the past year. We also used regression analyses to examine the effects of marijuana use at age 25 and at age 35, race, and their interactions on these same outcomes at age 35. There were no significant effects of quantity or frequency of use in the total sample or among users only on any of the health outcomes. There were also no health differences between Blacks and Whites except that Blacks were more likely to have been shot by age 35.
Conclusions: It appears that continuous monthly marijuana use from adolescence through emerging adulthood is not a high enough threshold to lead to negative health outcomes at least by young adulthood and that frequent use in emerging or young adulthood is also not related to health outcomes. Given that there were relatively few serious illnesses in this sample by young adulthood, it is possible that negative consequences of marijuana use will become evident at later ages. Prevention programs should highlight psychosocial rather than physical health consequences.