Source
Murdoch Children's Research Institute, Parkville, Victoria, Australia. carolyn.coffey@rch.org.au
Abstract
BACKGROUND:
Dependence increases the likelihood of adverse consequences of cannabis use, but its aetiology is poorly understood.
AIMS:
To examine adolescent precursors of young-adult cannabis dependence.
METHOD:
Putative risk factors were measured in a representative sample (n=2032) of secondary students in the State of Victoria, Australia, six times between 1992 and 1995. Cannabis dependence was assessed in 1998, at age 20-21 years.
RESULTS:
Of 1601 young adults, 115 met criteria for cannabis dependence. Male gender (OR=2.6, P < 0.01), regular cannabis use (weekly: OR=4.9; daily: OR=4.6, P=0.02), persistent antisocial behaviour (linear effect P=0.03) and persistent cigarette smoking (linear effect P=0.02) independently predicted cannabis dependence. Neither smoking severity (P=0.83) nor persistent psychiatric morbidity (linear effect P=0.26) independently predicted dependence. Regular cannabis use increased risk only in the absence of persistent problematic alcohol use.
CONCLUSIONS:
Weekly cannabis use marks a threshold for increased risk of later dependence, with selection of cannabis in preference to alcohol possibly indicating an early addiction process.