Study finds minimal physical effects in longtime marijuana users

A long-term study conducted in New Zealand has found that longtime users of marijuana experienced fewer physical health effects than regular users of tobacco or non-users of marijuana. The researchers, however, warned against interpreting the results as a confirmation that marijuana carries no harms.

“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,” said Madeline Meier, co-author of the latest study and assistant professor of psychology at Arizona State University.

Published online this week in JAMA Psychiatry, the new study encompassed nearly 1,000 individuals and looked at people who had smoked marijuana for up to 20 years. Examining a dozen measures of physical health, including lung function, blood pressure, glucose control and systemic inflammation, they found that marijuana smokers fared worse than non-smokers only in gum disease. Tobacco users, conversely, showed high rates of gum disease, reduced lung function, systemic inflammation and indicators of poor metabolic health.

The researchers found that the relative lack of physical health problems among long-term marijuana smokers was not a result of better baseline health status or healthier lifestyles.