A new study which will be published in the medical journal Addiction Research & Theory shows a dramatic increase in references to illegal drug use in rap music from 1979 through 1997. The study was led by Dr. Denise Herd, the UC Berkeley Associate Dean for Student Affairs and an Associate Professor of Behavioral Sciences, and it also tracked the link between illegal drug use and wealth, glamour and social standing.

Dr. Herd‘s group used the 341 most popular rap songs-as determined by Gavin and Billboard music-recorded during an 18 year period and searched for coded lyrics which glamorized or endorsed illegal drugs. And while different media outlets have reported on the study using inflammatory headlines such as, “Rap Music Glamorizes Drug Use,” it should be noted that Herd concedes that there are no statistics to factor in the shift in the perception of recreational marijuana use or the greater commercialization of rap music that occurred during the years the study focused on. It should also be noted that the study did not track whether the actual glamorization of illegal drug use led to increased drug usage.

“There is a common perception that drugs and rap music are inextricably linked, but that wasn’t always the case,” Herd tells Reuters. “The fact that rap music didn’t always have those drug references is compelling because it shows that this music didn’t depend on that as an art form. The direction of the music seemed to change with the music’s growing commercial success.”

The study will appear in the April edition of Addiction Research & Theory, and has already been reported on by the New York Times and Reuters. The report will be combined into a larger study by the Innovators Combining Substance Abuse program of The Robert Wood Johnson Foundation, which is the nation’s largest charitable organization devoted only to health care.

Additional information was provided by Sara Yang of UC Berkeley‘s Media Relations Department.