Long-term cannabis use is associated with few physical health problems in early midlife, according to new research published on Wednesday.

Researchers found that that the long-term recreational cannabis users studied suffered poor gum health but found no other physical health problems across a dozen measures. The study, published on Wednesday by JAMA Psychiatry, followed more than 1,000 New Zealanders from birth to age 38, tracking study participants’ self-reported cannabis use from age 18.

“One thing that surprised me is that we didn’t see associations between cannabis use and poorer lung function,” said Madeline Meier, a professor of psychology at Arizona State University and one of the paper’s authors.



Meier added that this finding is consistent with similar studies looking at the relationship between marijuana use and cardiovascular health. But she said unlike past studies, this one did not rely on participants to report their own wellbeing, and instead included two physical health exams.

The study compared the health of cannabis users to that of tobacco users, and found that while marijuana use was related to few physical health problems, tobacco use was associated with multiple issues, including worse lung function and metabolic health.

“What we’re seeing is that cannabis may be harmful in some respects, but possibly not in every way,” study co-author Avshalom Caspi said in a news release. “We need to recognize that heavy recreational cannabis use does have some adverse consequences, but overall damage to physical health is not apparent in this study.”

Previous research on the same sample of New Zealanders has shown that marijuana use is associated with increased risk of psychotic illness, IQ decline and downward socioeconomic mobility, Meier said.

In the new study, a team of researchers assessed periodontal health through clinical attachment loss, which essentially measures the loss of gum support around a tooth. According to the study, 55.61% of those with more than 15 years of regular cannabis use had periodontal disease, compared with 13.53% of those who never used cannabis. Poor periodontal health increases the risk for tooth loosening and loss.

The study did not identify any particular explanation for the correlation. Meier said that cannabis users’ poor gum health wasn’t explained by their dental hygiene or by tobacco smoking or alcohol abuse.

Michael Lynskey, professor of addictions at King’s College London, said the study was “methodologically” sound.

“It suggests that, in terms of the physical health measures that they studied, if there are any effects, they would be really quite small and minor compared with the effects of tobacco use,” he said.

Meier said further research was needed on how older adults handle long-term cannabis use.

