When [marijuana is] used in adolescents, it can permanently change the brain's chemistry and how the brain functions, said Francesca Filbey, a research scientist at the Mind Research Network at the University of New Mexico in Albuquerque. ... Filbey and another Mind research scientist, Kent Hutchison, have started a $930,000, five-year study to understand more about the complex workings of marijuana in adolescents. ... They want to study the brains of 96 adults, about half of whom used marijuana in their adolescent years and half who didn't. ... Participants must be over age 18. The researchers are looking both for those who smoked marijuana between ages 13-18 and those who didn't smoke marijuana between those ages for a control group..