Frequent Cannabis Use Linked With Fewer Good Mental Health Days

The study examined how cannabis use was related to self-reported overall, physical and mental health. It drew on individual-level data from the U.S. Behavioral Risk Factor Surveillance System, a health survey, collected between 2016 and 2023. The news coverage says the analysis included adults in 38 states, but it does not report the number of participants.

The researchers focused on how many days people used cannabis and how that pattern related to their reported health. Their main finding was that, among cannabis users ages 21 to 64, more days of cannabis use were associated with fewer days of good mental health. The association was particularly seen among males.

The study used an approach called instrumental variables. In plain language, this is a statistical method researchers use to try to separate cannabis use from other differences that may affect health. They tested several possible instruments, including state cannabis laws, cannabis prices and average cannabis use in matched age-and-gender groups.

The abstract says results differed depending on the health measure and instrument used. The finding about mental health came from the researchers’ strongest instrument: average cannabis use within matched gender-age groups. That detail matters because it suggests the results were not identical across every analysis.

For adults 65 and older, the findings were mixed. The supplied material does not give a single clear conclusion for that age group. The news coverage also reports that the main analyses did not show a consistent relationship between cannabis use and physical health in either age group.

A lack of a consistent link in these physical-health measures does not mean cannabis has no physical risks. It means this study did not find a stable pattern across the measures it examined. The supplied abstract does not list the specific physical-health measures, effect sizes or confidence intervals.

This was an analysis of survey data, not a clinical trial. People were not randomly assigned to use cannabis more often or less often. As a result, the study cannot establish that more frequent cannabis use caused fewer good mental health days. Other factors, including mental health challenges that may influence cannabis use, could help explain part of the relationship.

The data were also based on people’s own reports of cannabis use and health. The supplied materials do not provide the study’s sample size, a definition of “younger” adults beyond the 21-to-64 group, or details on whether the same people were followed over time.

Further research would need to clarify why the association appeared stronger among males, whether it holds in other populations and how much the reported mental-health difference was. Studies with more detailed information over time could help researchers better understand the direction of the relationship.