A nationwide rise in cannabis use is not the result of medical or social legalization in a growing number of states, according to a new study published this week in Addiction, a monthly peer-reviewed scientific journal.

“Marijuana policy liberalization over the past 20 years has certainly been associated with increased marijuana use,” the study found. “However, policy changes appear to have occurred in response to changing attitudes within states and to have effects on attitudes and behaviors more generally in the U.S.”

Researchers at the Public Health Institute’s Alcohol Research Group analyzed data from seven periodic National Alcohol Surveys and pulled results on cannabis use against changes in state laws.

The results indicated societal factors that affect populations across age and generational group are the main driver of rising cannabis use prevalence. Medical and recreational cannabis policies did not have any significant association with increased cannabis use.

The study said, “the steep rise in marijuana use in the United States since 2005 occurred across the population and is attributable to general period effects not specifically linked to the liberalization of marijuana policies in some states.”