The presence of multidimensionality in PDs can pose problems in interpretation. PD symptom criteria include both externalizing and internalizing features, despite that individual PDs may have different relationships with these liability dimensions. Within the externalizing-internalizing framework, PD symptom criteria reflecting impulsivity, disinhibition, anger, or antagonism may relate to externalizing, while negative emotionality or affective instability may relate to internalizing. The exact nature of the relationship between the PDs and fear is not clear. Negative affect and emotional regulation are important features among PDs, but there may be important distinctions when related to externalizing and internalizing disorders. It is noteworthy that the two internalizing factors may be distinguished in terms of avoidance of social situations and/or specific objects compared with depressed mood or loss of interest or pleasure. PD negative emotions, for example, may have greater levels of arousal, or may be more readily activated with respect to perceived environmental threat when compared to more dampening (inhibited) effects associated with stress. More detailed analyses based on symptom criteria may help explicate the underlying structure of these disorders. Analysis of PD symptom
