Percentage Increases in Cannabis Use Were an Imperfect Dependence Indicator in Adolescents
Defining cannabis tolerance by the percentage increase in the amount needed to feel high only moderately distinguished adolescents with and without dependence in a study using DSM-IV-era criteria. A large reported increase was therefore not a self-sufficient diagnostic result.
The definition was operational, not universal
The investigators tested a change-based measure: how much the quantity needed to get high had increased. Two adolescent cannabis-user samples, numbering 417 and 380 and spanning ages 12 to 19, supplied the data. Median reported increases differed between the samples, at 300% and 175%.
Classification performance was limited
The tolerance measure had only moderate overall sensitivity and specificity for distinguishing participants with and without cannabis dependence. Sensitivity and specificity concern classification performance, rather than proving that tolerance has no clinical relevance. The result cautions against treating this particular quantity-change measure as a complete assessment.
The historical diagnostic framework matters
This research evaluated DSM-IV cannabis tolerance and dependence constructs. It should not be presented as an evaluation of every current diagnostic definition or as a current diagnostic checklist. Nor does a percentage increase alone describe product composition, delivered THC exposure or the person's functioning at a particular time.
The useful distinction is between a report of changing drug effects and a validated conclusion about a broader disorder. This study supports asking how tolerance was defined and measured before relying on it as a diagnostic indicator. It does not authorize diagnosing or excluding a disorder from a single consumption-history number.
Related: interpreting cannabis tolerance claims.
Research cited
Chung T; Martin CS; Winters KC; Cornelius JR; Langenbucher JW. Limitations in the assessment of DSM-IV cannabis tolerance as an indicator of dependence in adolescents. Experimental and clinical psychopharmacology (2004). doi:10.1037/1064-1297.12.2.136. Findings discussed from the study abstract.
