We also examined the discriminant validity or specificity of neuroticism to internalizing psychopathology. To examine discriminant validity, we analyzed substance use disorders given that Krueger (1999) used substance use disorders as indicators of externalizing psychopathology. Although neuroticism is hypothesized to be related to internalizing psychopathology, Krueger, Caspi, Moffitt, Silva, and McGee (1996) also found that individuals with diagnoses of substance dependence scored high on a measure of negative emotionality. Thus, we anticipated an association between substance use and neuroticism.
