Marijuana use can impair cognitive function — especially for youth — according to a new study published in the journal Addiction.

CNN interviewed one of the study’s authors, writing,

“Our study enabled us to highlight several areas of cognition impaired by cannabis use, including problems concentrating and difficulties remembering and learning, which may have considerable impact on users’ daily lives,” said coauthor Dr. Alexandre Dumais, associate clinical professor of psychiatry at the University of Montreal.

“Cannabis use in youth may consequently lead to reduced educational attainment, and, in adults, to poor work performance and dangerous driving. These consequences may be worse in regular and heavy users,” Dumais said.

This latest research underscores the toll that marijuana use can take on the brain — especially for teenagers and young adults.

Researchers have found time and again that marijuana is dangerous.

Last spring a study out of California found infants were 35% more likely to die within a year of birth if their mother used marijuana heavily; the study also found that infants were more likely to be born preterm, have a low birth weight, and be small for their gestational age.

Researchers have linked marijuana use with psychosisschizophreniadepression and suicide.

A study published in the Canadian Medical Association Journal last year found adults under age 45 who frequently used marijuana were roughly twice as likely to suffer heart attack as adults who did not use marijuana.

A report published in the Journal of the American Medical Association found that states that legalized commercial marijuana sales saw self-harm rates rise by 46% among men ages 21 to 39.

All of this comes as groups work to legalize recreational marijuana in Arkansas and pro-marijuana political action committees work to elect candidates who support marijuana.

As we have said time and again, marijuana may be many things, but “harmless” simply is not one of them.