The influence of program mediators on eleventh grade outcomes for seventh grade substance users and nonusers

Brent Teasdale*, Peggy C. Stephens, Zili Sloboda, Scott F. Grey, Richard C. Stephens

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

15 Scopus citations


Objectives: In their work examining the effects of the Take Charge of Your Life (TCYL) program, Sloboda and colleagues (This Issue) found that the TCYL program had significant positive effects on baseline marijuana users and significant negative effects on baseline nonusers of cigarettes and alcohol. Methods: Mediational analyses were used to understand why the program had these differential impacts on baseline users and nonusers. Results: Path models for binary outcomes revealed significant program impacts on marijuana normative beliefs and refusal skills. The treatment impacts were between 1.5 and 3 times larger for the baseline users than for nonusers. These direct effects of the program on normative beliefs and refusal skills mediated the treatment impact on use for baseline marijuana users. In contrast, the negative treatment effects on alcohol and cigarette use could not be explained by the program's targeted mediators (normative beliefs, refusal skills, consequences, attitudes and intentions). The direct effects of treatment on use for the baseline nonusers of cigarettes and alcohol remain unexplained. Conclusions: Possible explanations for this pattern and implications for strengthening universal prevention programs that are delivered to both users and nonusers are discussed. The importance of mediational analyses for programs that show negative impacts, as well as for those that show positive impacts is stressed.

Original languageEnglish
Pages (from-to)11-18
Number of pages8
JournalDrug and Alcohol Dependence
Issue number1-3
StatePublished - 1 Jun 2009
Externally publishedYes


  • Mediational analysis
  • Program impact
  • Substance use


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