As far as I know, no study has proven that LSD use causes more adverse side effects in teens.
However, Cannabis, alcohol, tobacco, MDMA, cocaine, amphetamine, and surely some other drugs all have more adverse side effects when teens use them. Adolescent minds and bodies are simply more vulnerable to their effects.
Is LSD as dangerous to teens as those other drugs? Probably not.
Is LSD more dangerous for teens than for adults? Probably, yes.