Kaila White

The Republic | azcentral.com

An Arizona State University assistant professor is among the researchers whose new study finds that long-term marijuana use – for up to 20 years – is associated with gum disease but none of 11 other physical health problems by age 38.

Madeline Meier, an assistant professor of psychology at ASU, is known in part for her work on a 2012 study that found that long-term marijuana use was associated with cognitive problems and a drop in IQ.

For both studies, she, along with Duke University professors, led a research team that analyzed data collected about nearly 1,000 New Zealanders from birth, including information about measures of their physical health and marijuana use.

Meier and team tested associations between marijuana use over the course of 20 years and a dozen measures of physical health, including periodontal health, lung function, systemic inflammation, metabolic health, blood pressure and body-mass index. For this study, participants were 38 years old.

In conclusion, they found that "cannabis use for up to 20 years is associated with periodontal disease but is not associated with other physical health problems in early midlife," according to the study published in JAMA Psychiatry.

Bad teeth and little else?

Study participants who smoked marijuana had poor gum health, which can result in tooth loss, that could not be explained by tobacco smoking, alcohol abuse, or less tooth brushing and flossing.

As for the other measures of physical health, the lack of physical health problems among marijuana smokers was not attributable to them having better health to begin with or healthier lifestyles, according to the study.

What surprised the researchers

First, they found no association between marijuana use and reduced lung function, which is "somewhat puzzling" since tobacco use is associated.

The "second surprising instance" is that they found no association between marijuana use and cardiovascular risks such as high blood pressure.

Limitations of the study

"Although this investigation is the most comprehensive study to date, cannabis use may be associated with health problems not studied here or with those that tend to emerge later in life, such as cancer," said the report's conclusion.

Beyond that, the study notes other limitations, including that most participants who used marijuana also smoked cigarettes. Participants began smoking in the 1980s and 1990s, and marijuana is much more potent now.

If people begin to use marijuana the way they do tobacco, smoking multiple times a day, more health problems may emerge, the study said. The study is not relevant to older adults or people who are already sick.

"Our 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 report said.