Bias in treated samples can be associated with a number of factors that may contribute to the decision to seek treatment. Indeed, findings from recent studies reveal that AD individuals in treatment, compared to treatment-naïve alcohol dependent individuals (TNAD), have a higher incidence of psychiatric co-morbidity, including externalizing (primarily antisocial) disorders, mood disorders, and anxiety disorders (Di Sclafani et al., 2008; Fein et al., 2002; Moss et al., 2007), as well as greater dysfunction in intimate relationship and vocational functioning (Tucker et al., 2004). In addition, AD individuals in treatment have reported more severe dependence, more emotional problems, and less engagement in everyday activities than TNAD individuals (Kaskutas et al., 1997; Lloyd et al., 2004; Lukassen et al., 2005; Tucker et al., 2004). Perhaps the most telling evidence of bias in treated AD samples comes from Fein and Landman (2005), who demonstrated differences in alcohol use trajectories between treated AD and TNAD individuals in the period after meeting “heavy drinking” criteria. Treated alcoholics had higher average and peak alcohol doses than did TNAD. In fact, the treated alcoholics had alcohol doses over 50% higher than treatment naïve alcoholics in the years just after they met criteria for heavy alcohol use.
