Age of onset of cannabis use and substance use problems: A systematic review of prospective studies.

Background: The association between the age of cannabis use (CU) onset and substance use (SU) problems has been extensively studied, yet findings remain inconsistent.

Aims: This systematic review aimed to examine prospective studies on the association between age of CU onset and later SU problems, controlling for key individual, social, and SU-related risk factors.

Methods: PsycINFO, Web of Science and PubMed were searched for studies published between January 2000 and December 2024.