This seems an intuitive result:

Younger age at first drug use tied to faster transition to substance use disorder
Younger age at drug initiation is associated with a faster transition to substance use disorder (SUD), according to a research letter published online March 29 in JAMA Pediatrics.
And, although I am generally a “live and let live” kind ‘a guy, the more we decriminalize or legalize drugs, the more “younger age” first use you’ll have (even if it remains illegal for them).