Several theorists have posited that one factor is common to depression and anxiety, whereas others factors are more specific to depression than to anxiety and vice versa. Clark and Watson (1991), in their tripartite model, posited that high negative affect (NA) was common to anxiety and depression, but low positive affect was specific to depression, and physiological hyperarousal was specific to anxiety. Mineka, Watson, and Clark’s (1998) integrative hierarchical model posited that high NA is a common factor in the mood and anxiety disorders, but that individual disorders contain relatively specific elements (see also Brown et al., 1998). Clark, Watson, and Mineka (1994) argued that stable traits may also be common factors in anxiety and depression. Specifically, they argued that trait NA (i.e., neuroticism) may be a common vulnerability factor in anxiety and depression.
