Daily use of cannabis as well as past month rates rose for both men and women aged 26 and older in states with medical cannabis laws in effect. Cannabis use among those younger than 26 years old was generally unaffected by changes in the law.

In states with medical cannabis laws, daily cannabis use for male users age 26 and older increased from 16.3 percent to 19.1 percent, and for women, from 9.2 percent to 12.7 percent. Past month use among men in the same age bracket increased from 7.0 percent before the laws passed to 8.7 percent following their passage, and for women rose from 3.0 percent before to 4.3 percent after. There were no significant rises in past-year cannabis use disorder for any age or gender group subsequent to passage of the laws.

Daily use was generally higher among entities aged 18-25 compared with those ages 12-17 and those 26 or older, irrespective of their state’s laws around marijuana. Daily cannabis use promotions health concerns as the brain doesn’t fully mature until age 25.

Rising rates of cannabis use raises concerns regarding associated increases in heavy use of marijuana and marijuana use disorder. Earlier research by Columbia researchers estimated that 16.2 percent and 57.2 percent of daily cannabis users meet criteria for DSM-IV abuse and dependence diagnosis, respectively.

In fact, in spite of public health concerns concerning increased use of pot and enactment of cannabis laws, some positive outcomes have been related with the laws, including reduced opioid use and decreased alcohol consumption — the latter tied to declining rates of traffic injury fatalities at the state level.

Because most states in the sample more recently passed medical cannabis laws, it is possible that not enough time has elapsed to observe more significant changes in cannabis use disorder across age-gender subgroups. Given the impact the disorder may have on individuals, families and society, cannabis use should continue to be monitored regularly. Building the evidence base by age and gender is critical in helping public health professionals better understand which groups, may be most affected by medical cannabis laws and target public health programming accordingly.