“…Under the influence of American researchers it became increasingly clear that the drug problem was not an isolated problem, but a complex constellation of intervening factors (Carroll & McGinley, 1998;De Leon & Jainchill, 1991). The reciprocal influence of medical (Brown, Melchior, Waite-O'Brien, & Huba, 2002), social and psychological problems (Jainchill, Hawke, & Yagelka, 2000), and comorbid psychiatric disorders (Brown et al, 2002;Carroll & McGinley, 1998) became generally accepted and further investigated by European researchers (Broekaert, Haack et al, 2002;Ravndal & Vaglum, 1994). In turn, TC staff members gained awareness of the high rate of psychiatric comorbidity among the substanceabusing population seeking treatment and learned that the nature and severity of the problems differ greatly between major subgroups.…”