evidence: Study Suggests Marijuana Use Damages Brain Immune Cells Vital to Adolescent Development 10/25/2023 In a mouse study designed to explore the impact of marijuana’s major psychoactive compound, THC, on teenage brains, Johns Hopkins Medicine researchers say they found changes to the structure of microglia, which are specialized brain immune cells, that may worsen a genetic predisposition to schizophrenia. The findings, published Oct. 25 in Nature Communications, add to growing evidence of risk to brain development in adolescents who smoke or eat marijuana products. [...] "This kind of study is critical right now because marijuana is becoming more mainstream, and we are just beginning to understand how it affects the brain immune cells," says Yuto Hasegawa, Ph.D., research associate of psychiatry and behavioral sciences at the Johns Hopkins University School of Medicine and the study’s leading author.