Middle-age people who have smoked marijuana for many years may have a higher risk of developing gum disease, according to a new study.
However, the study did not find a link between long-term marijuana use and several other health problems associated with cigarette smoking, the researchers said.
"What we're seeing is that cannabis may be harmful in some respects, but possibly not in every way," Avshalom Caspi, a co-author of the study and a professor of psychology and neuroscience at Duke University, said in a statement. "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." [11 Odd Facts About Marijuana]
In the study, the researchers looked at 1,037 people who were born in New Zealand in 1972 or 1973, and followed them until the people were 38 years old. The researchers examined whether the people had used marijuana when they were between 18 and 38, and whether they had physical health problems at age 38.
The researchers found that, among the 38-year-olds who had regularly smoked pot for 15 to 20 years, 55.6 percent had gum disease, also called periodontal disease. In comparison, only 13.5 percent of the 38-year-olds who had never used marijuana had gum disease. In some cases, this disease may lead to tooth loss.
The results also showed that the people who had smoked marijuana for up to 20 years had brushed their teeth and flossed less frequently than those who had never smoked marijuana, according to the findings, published today (June 1) in the journal JAMA Psychiatry. However, the less-frequent brushing and flossing did not explain the link between marijuana use and gum disease, which suggests that marijuana use itself may lead to damage to the gums. [5 Surprising Ways to Banish Bad Breath]
Researchers have long known that cigarette smoking has been associated with a higher risk of gum disease, said Dr. Ronald P. Burakoff, chairman of dental medicine at Northwell Health in New Hyde Park, New York, who was not involved in the study. "So I am not surprised that marijuana use also is associated with periodontal disease," Burakoff told Live Science.
In the new study, the researchers also looked at the dental and general physical health of 484 people in the study who had smoked cigarettes on a daily basis at some point in their lives. In line with previous research, they found that those people were also more likely to have gum disease than those who had never smoked.
But these people were also more likely to have problems with their lung function, higher blood sugar levels and inflammation than those who had never smoked cigarettes.
In contrast, when the researchers looked at the same aspects of lung function and cardiovascular health among the people who had smoked marijuana for up to 20 years, they did not find these aspects were worse than they were in the people who had never smoked marijuana.
One limitation of the new study was that the researchers looked only at specific aspects of the people's health assessed at a specific age, the researchers said. This means that the use of marijuana still may be linked to other health problems, such as cancer, that tend to occur later in life, they said.
Previous research has found links between the use of marijuana and weight gain, brain changes and the worsening of sexual function, among other health problems.
The new results "should be interpreted in the context of prior research showing that cannabis use is associated with accidents and injuries, bronchitis, acute cardiovascular events and, possibly, infectious diseases and cancer, as well as poor psychosocial and mental-health outcomes," the researchers wrote.
Originally published on Live Science.