A new study has found no link between regular, long-term marijuana use and physical health issues, with the exception of a higher incidence of gum disease.
The new research, conducted by a team led by Arizona State University's Madeline Meier, studied 1,037 people in New Zealand to see what effect their marijuana usage had on their health, from the time of birth until middle age, according to the Independent. The study, which was published in the journal JAMA Psychiatry, tracked the subjects' lung function, cholesterol, weight, blood pressure, and blood sugar.
The study, which was controlled for factors such as tobacco use, showed that those who used marijuana regularly had a higher rate of gum disease, but aside from dental health, their health was unaffected by the pot itself.
"In general, our findings showed that cannabis use over 20 years was unrelated to health problems in early midlife,” reads the study.
“Across several domains of health (periodontal health, lung function, systemic inflammation, and metabolic health), clear evidence of an adverse association with cannabis use was apparent for only one domain, namely, periodontal health," the researchers found.
While the study did find that those who smoked pot more regularly were less likely to brush and floss daily than those who did not smoke at all, the link between pot and gum disease continued even after the researchers adjusted to control for dental hygiene habits.
Notably, the study only looked at the relationship between long-term pot smoking and physical health, and not on mental health. While this study found no link between marijuana use and physical health problems outside of gum disease, Meier has used the same data set to investigate pot's effect on mental health, and found evidence of a decline in IQ for those who used the drug long-term.
Other follow-up studies investigating the same effects, however, didn't find evidence of IQ decline connected to smoking marijuana. A study released in January tracked teenage twins who either used or abstained from pot for 10 years, finding no link between smoking marijuana and a loss of IQ.
"This does not mean that heavy use in adolescence is problem-free,” statistician Nicholas Jackson, from the University of Southern California in Los Angeles, told Science magazine. He added that other aspects of a teen's daily functioning could be negatively affected by regular pot use.