Recent conceptualizations, based on nationally representative samples, have proposed that psychiatric disorders are best understood along broad dimensions of externalization and internalization. Factor analytic studies have identified a 3-factor model that includes one externalizing factor represented by antisocial personality disorder (ASPD) and substance use dependence and two correlated internalizing factors labeled “distress” (major depression, dysthymia, and generalized anxiety) and “fear” (social phobia, specific phobia, and panic with and without agoraphobia). Studies have indicated overall consistency with these dimensions, despite some variation according to diagnosis and age composition of samples (Beesdo-Baum et al., 2009; Cox et al., 2002; Farmer et al., 2009; Kendler et al., 2003; Krueger et al., 1998, 2005; Markon and Krueger, 2005; Vollebergh et al., 2001).
