Adolescent precursors of cannabis dependence: findings from the Victorian Adolescent Health Cohort Study.
COFFEY, CAROLYN; CARLIN, JOHN B.; LYNSKEY, MICHAEL; LI, NING; PATTON, GEORGE C.
[Article] British Journal of Psychiatry. 182:330-336, April 2003.

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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.

Declaration of interest: None.

(C) 2003 The Royal College of Psychiatrists