As legal marijuana begins its march across the U.S. of A., the allure of billions in state tax revenue will start to provide a pretty hefty incentive to push aside the skeptics who would prefer to keep the plant locked down.

But as with any change in the availability of drugs (Prohibition or otherwise), we'll start to notice that weed may have more effects than we had previously anticipated. While we have some good ideas about how weed affects the human body—specifically your workouts and your workout recovery—it's possible that marijuana's long-term effects will start to manifest themselves as more people have access to the drug at an earlier age.

For example: A quarter of young adults who were heavy pot users had an anxiety disorder as a teen or young adult, says a recent study from the Duke University Medical Center.

The research tracked more than 1,000 people living near the Great Smoky Mountains in North Carolina from 1993 until 2015, making note of lots of life data, including mental health and use of drugs and alcohol. (Another interesting note: Many people who didn’t have problems with heavy pot use until later in life were mistreated by adults and bullied by peers early in life, the researchers found.)

"Given that more states may be moving toward legalization of cannabis for medicinal and recreational purposes, this study raises attention about what we anticipate will be the fastest-growing demographic of users—adults," said lead author Sherika Hill, Ph.D., an adjunct faculty associate at the Duke University School of Medicine. "A lot of current interventions and policies in the U.S. are aimed at early adolescent users. We have to start thinking about how we are going to address problematic use that may arise in a growing population of older users."

For more, check out our feature on how weed specifically affects fit guys.