Long-term marijuana use is associated with periodontal disease, according to a new study in JAMA Psychiatry. However, chronic pot smokers did not develop other health problems associated with tobacco use, such as decreased lung function and increased inflammation, researchers concluded.
Citing the growing support for cannabis legalization in the U.S., the international team said the study can inform policymakers, healthcare professionals, and the public about the potential consequences of cannabis use (JAMA Psychiatry, June 1, 2016).
"We can see the physical health effects of tobacco smoking in this study, but we don't see similar effects for cannabis smoking," researcher Madeline Meier, PhD, an assistant professor of psychology at Arizona State University, told DrBicuspid.com.
Cannabis and oral health
Meier said dentists should discuss with their patients the potential effects of cannabis use on oral health, however.
Madeline Meier, PhD."Dentists and physicians should convey to patients that their cannabis use puts them at risk for tooth loss," she said.
The long-term study began with 1,037 New Zealanders; 947 were analyzed from birth to age 38, and the researchers collected information about their cannabis use over a 20-year period, from age 18 to 38. The participants included 484 who had ever smoked tobacco daily and 675 who had used cannabis.
The participants had physical health exams when they were 26 and 38 years old, allowing the researchers to test associations between cannabis use and a variety of physical health outcomes in midlife, including periodontal health, lung function, and systemic inflammation. About half the participants were male, all were born in 1972 or 1973, and most of the participants identified as white.
The researchers assessed several measures of metabolic syndrome, including waist measurement, high-density lipoprotein (HDL) cholesterol, triglycerides, blood pressure, glucose control, and body mass index.
Few overall health effects
Cannabis users showed an increase in periodontal disease from age 26 to 38; however, they showed no other signs of poor health. By comparison, tobacco users showed poor periodontal health, decreased lung function, systemic inflammation, and lower metabolic health.
The researchers found that 12.3% of the participants who never used tobacco daily had periodontal disease, compared with 52.9% of those who smoked a pack of cigarettes daily for 15 years.
Meier said she had expected more negative health effects from cannabis use.
"I was surprised that marijuana use was not associated with reduced lung function," she said.
And despite marijuana's reputation for stimulating "the munchies" -- craving sweets and snacks -- long-term users had smaller waistlines, the study revealed.
The researchers were hard-pressed to explain why chronic pot use didn't result in more significant health problems.
"The general lack of association between persistent cannabis use and poor physical health may be surprising," they noted.
The group speculated that cannabis users could have healthier lifestyles, such as following better diets or exercising more. But tests showed no connection between cannabis use and healthier lifestyles.
Some cannabis users brushed and flossed less and were more likely to be heavy drinkers. Yet the decline in periodontal health in pot smokers was not explained by tobacco use, alcohol abuse, or less tooth brushing or flossing.
The researchers noted that the study did not examine the health effects of cannabis use that tend to emerge later in life, such as cancer.
"Cannabis use for up to 20 years is not associated with a specific set of physical health problems in early midlife. The sole exception is that cannabis use is associated with periodontal disease," the group concluded.
However, prior research has shown 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 authors noted.
"We don't want people to think, 'Hey, marijuana can't hurt me,' because other studies on this same sample of New Zealanders have shown that marijuana use is associated with increased risk of psychotic illness, IQ decline, and downward socioeconomic mobility," Meier said.
