To the Editor: We would like to thank Drs. Schneier, Liebowitz, and Laruelle for their comments regarding our article, which described the association between low dopamine transporter binding and detached personality. Indeed, it may be difficult to discern the psychological basis for avoidant behavior with a self-rating instrument such as the Karolinska Scales of Personality. Patients with either social phobia or schizoid personality disorder do experience discomfort when interacting socially, although this is because of anxiety (often in the presence of a desire to socialize) in the former and more because of a lack of interest in the latter. Although many of the detachment items in the Karolinska Scales of Personality do reflect more aloofness than phobic anxiety about socialization (e.g., "I am [not] deeply moved by other people’s misfortunes," "I [do not] want to confide in someone, when I am worried and unhappy"), we agree that the association between detached behavior and low dopaminergic transmission reported by us and others (Farde et al., 1997; Breier et al., 1998) may relate to similar findings on social phobia (Tiihonen et al., 1997; Schneier et al., 2000). However, we also reported a strong positive correlation between scores on the social desirability subscale of the Karolinska Scales of Personality and dopamine transporter binding, which suggests also that motivational aspects of social behavior play a part in the described phenomenon. It is also worth noting that up to 60% of patients with social phobia also fulfill the DSM-IV criteria for avoidant personality disorder (1). This has not been fully addressed in previous studies examining dopaminergic neurotransmission in social phobia (Tiihonen et al. 1997; Schneier et al., 2000).

We feel that it is unlikely that the association we reported could be caused by subjects in our study group with social phobia. First, any direct comparisons of scores on the Karolinska Scales of Personality between diagnostic groups (healthy versus social phobic) from different populations (European versus United States) without normative transformation of the personality data should be made with caution. Second, although social phobia was not excluded with a structured instrument such as the SCID (a thorough clinical interview for axis I diagnoses), a medical history focused on psychiatric and neurologic illness was obtained from healthy volunteers. In addition, the recruitment procedure did not favor subjects with social anxiety. Considering that the point prevalence of social phobia in the general population is between 5% and 10% (2), the risk for including persons with social phobia in our screened group of 18 healthy subjects was low. However, we certainly agree that a detailed psychiatric examination of the subjects is highly important in studies on temperament and character.