age of that sample was 10.88 years (s.d. = 2.8). Our sample was ascertained through substance-dependent probands, although phenotypic information was available on the controls, in addition to the cases, which enabled us to study CD symptomatology among individuals with and without alcohol dependence. Furthermore, CD symptoms were assessed retrospectively in our sample, among adults who had passed through the period of risk for childhood CD. Accordingly, the different sample characteristics may have yielded populations with different underlying etiological factors.
