Alcohol and marijuana use during adolescence may lead to cognitive complications, according to findings published in the journal of Alcoholism: Clinical and Experimental Research.

For the trial, researchers conducted a series of psychological exams on three groups – 19 teenagers with substance dependency, 14 with a family history of usage who don’t drink or smoke and 15 individuals in a control group.

The results of the tests showed that those who frequently drank alcohol and smoked marijuana suffered from some brain-related problems. Furthermore, as alcohol consumption increased, more damage was done to the parts of the brain that are linked to planning performance and task completion, while marijuana use affected memory function.

Susan F. Tapert, co-author of the study, stated that “intense drinking during adolescence leads to delays or incomplete development of frontal brain regions, which in turn leads to problems with attention and executive functioning.

Based on these results, the team plans to continue their research by determining if alcohol consumption could cause dose-dependency, and if it is possible to develop intervention programs.

Approximately 11 percent of alcohol consumption in the U.S. is among people aged 12 to 20 years, according to the Center for Disease Control and Prevention.