Yes. During adolescence some significant brain changes occur, these changes will determine the brains natural level of happiness. These changes are directed by

Yes. During adolescence some significant brain changes occur, these changes will determine the brains natural level of happiness. These changes are directed by a class of neurotransmitters called monoamines. A lot of drugs influence the amount of these Monoamines in the synapse, which causes their euphoric effects. When you take drugs during adolescence it will change the level of monoamines and thus alter brain development. This is why pharmacologists are so reluctant to let children go on antidepressants, we don't yet have enough data to confidently say what the effects are.