1), hereby controlling for alcohol and tobacco use at T2 and T3. Path analysis revealed that the MK-2206 mw model represented the data well [χ2 (34, N = 1,449) = 270.2, p < .001; RMSEA = .07, CFI = .96]. The paths between externalizing

behaviour problems measured at T1, T2, and T3 were all significant (T1-T2; z = 11.8, p < .05; T1-T3; z = 4.9, p < .05; T2-T3; z = 11.5, p < .05). The path between cannabis use T2 and T3 was also significant (z = 5.4, p < .05). In addition, the paths between externalizing behaviour and tobacco use were all significant (T2; z = 11.7, p < .05; T3; z = 16.9, p < .05). Also, the paths between externalizing behaviour and alcohol use were all significant (T2; z = 8.4, p < .05; T3; z = 6.6, p < .05). The same occurred with cannabis use, where the paths between cannabis use and tobacco use were significant at T2 (z = 17.8, p < .05) and T3 (z = 18.0, p < .05) and also with alcohol use at T2 (z = 2.9, p < .05) and T3 (z = 5.7, p < .05). Moreover, externalizing behaviour and cannabis use significantly correlated at T2 (r = 0.19, p < .05) and T3 (r = 0.34, p < .05). Externalizing behaviour at T1 significantly predicted cannabis use at T2 (z = 3.8, p < .05) and T3 (z = 2.7, p < .05). Externalizing behaviour

INCB28060 supplier at T2 also significantly predicted cannabis use at T3 (z = 4.0, p < .05). Cannabis use measured at T2 did not show significant association with externalizing behaviour problems at T3 (z = −1.4, p > .05) ( Fig. 1). In the present longitudinal study, 1,449 respondents were followed from the age of 11 to 16 to assess the relationship between

both internalizing and externalizing problems and cannabis use. Two different hypotheses, the damage hypothesis and the self-medication hypothesis, were tested using path analyses, thereby controlling for possible confounding factors. First, our data showed that cannabis use is strongly related to externalizing behaviour problems in early adolescence, including aggressive and delinquent behaviour. This result is largely in agreement with previous studies (Fergusson for et al., 2007, Fergusson et al., 2002, Khantzian, 1985 and Monshouwer et al., 2006). As expected, our data supported the self-medication hypothesis, indicating that externalizing problems precede cannabis use during adolescence and not the other way around. Specifically, in our study, externalizing problems at age 11 were associated with cannabis use at age 13 and age 16. Also, externalizing behaviour at age 13 predicted cannabis use at age 16. These results are in agreement with a number of other studies. King et al. (2004), for example, also showed that externalizing psychopathology at age 11 predicted cannabis use at age 14, although it did not take into account potential confounders, such as the use of other substances. Korhonen et al. (2010) recently showed that early onset of smoking predicts cannabis initiation, while controlling for co-occurring externalizing behaviour problems. Whereas Korhonen et al.