Evidence that one factor is common to mood and anxiety disorders is consistent with models that posit the existence of a personality trait – neuroticism (a trait disposition to experience NA) – that acts as a nonspecific vulnerability factor to the internalizing disorders (e.g., Eysenck, 1967; Gray, 1982). Moreover, many studies, have addressed the relationship between neuroticism and the dimension of internalizing psychopathology. For example, Brown et al. (1998) found that trait NA was common to depression and anxiety as measured by a combination of interview and questionnaires. Low trait positive affect was common to depression and social phobia, and autonomic arousal was related to panic and agoraphobia. Khan, Jacobson, Gardner, Prescott, and Kendler (2005) examined the population-based Virginia Twin Registry, which consisted of Caucasian adults, and found that neuroticism accounted for 20-45% of comorbidity among various mood and anxiety disorders. Weinstock and Whisman (2006) found that individuals with comorbid mood and anxiety disorders scored higher on neuroticism than those individuals with either a mood or an anxiety disorder alone. In turn, individuals with either a mood or anxiety disorder
