Massive study of adolescent brains puts “gateway drug" theory into question

Those who grew up when Drug Abuse Resistance Education pamphlets were common in the school counselor's office are probably familiar with the “gateway drug” theory, which suggests the use of one substance like cannabis or alcohol will send a person down the path to try “harder” drugs like cocaine or meth later in life. Writing in JAMA Network Open, Dr. Alex Miller, the study’s lead author and an assistant professor of psychiatry at Indiana University School of Medicine, and his team found that adolescents who initiated substance use had differences in certain brain structures compared to kids who didn’t use drugs. “The study sort of helps us highlight which regions may be important to further explore, with respect to their association as pre-existing risk factors for substance use initiation,” Miller told Salon in a phone interview. This study "casts doubt on some of the prior gateway theories because it seems like many of the same brain differences that are a risk factor for nicotine use are also a risk factor for alcohol and cannabis use.” The differences observed in the study were small but statistically significant within a large sample size close to 10,000 participants, Miller said.