In the study, which just appeared in the Journal of Neuroscience, the researcher gave cocaine and amphetamine to groups of adult, adolescent and baby mice every day for a week.
Then they compared the chemistry in two sections of the mice brains against that of a control group. Because mice have many of the same brain functions as humans, scientists believe the results should shed light on our brains, Ehrlich says.
After taking the drugs, all the mice had elevated levels of an addiction-marking protein in the part of the brain that controls movement and hyperactivity. But adolescent mice also had high levels of the protein in the part of the brain that controls the “reward” mechanism.