associated with the risk factors we examined. One possible explanation for the decreased rates of major depressive disorder and regular smoking in Group 3 is that both conditions are associated with problem drinking, which we know to be lower in those reporting an older age at Time 2. The association of CSA and cannabis abuse with younger age at second report may reflect a tendency for individuals who have experienced childhood maltreatment and/or abused substances to be poor historians (but why the same pattern is not observed for CPAN as for CSA is unclear). Although we cannot yet explain these patterns, it may be possible to apply this information to make statistical adjustments for systematic biases in retrospectively reported age at initiation of alcohol use.
