In contrast, a number of studies have found that smoking is predictive of high school dropout (Aloise-Young et al., 2002; Bray et al., 2000; Ellickson et al., 1998), and of failure to pursue education beyond high school (Chassin et al., 1992; Cook & Moore, 1993; Gfroerer et al., 1997) even after controlling for covariates. Similarly, most studies examining adolescent cannabis use (especially early initiation) suggest that cannabis use remains significantly associated with reduced educational attainment even after controlling for covariates (Bray et al., 2000; Brook et al., 1999; Chatterji, 2006; Fergusson et al., 2003; Horwood et al., 2010; King et al, 2006; Lynskey et al., 2003a; Lynskey & Hall, 2000; Macleod et al, 2004; Register et al., 2001; van Ours & Williams, 2009). Interestingly, McCaffrey et al. (2010) found that the association between cannabis use and school dropout became non-significant once cigarette use was included.
