The relationship between avoidant personality disorder, social anxiety disorder and normative personality traits: a longitudinal twin study

Avoidant personality disorder (AvPD) and social anxiety disorder (SAD) share risk factors to a substantial degree, and both are characterized by the experience of anxiety in social situations. We investigated whether these... [ view full abstract ]

Avoidant personality disorder (AvPD) and social anxiety disorder (SAD) share risk factors to a substantial degree, and both are characterized by the experience of anxiety in social situations. We investigated whether these disorders are differentially related to normative personality traits. We also examined the underlying genetic and environmental influences on these associations to identify disorder-specific effects. AvPD and SAD were assessed in a population-based sample of 1,761 female twins at baseline, and 1,471 of these 10 years later. At the second wave of data collection we also measured the Big Five personality traits. Associations between AvPD, SAD and personality traits were investigated with multivariate biometric analyses. On the phenotypic level, AvPD was associated with lower levels of extraversion, openness to experience, and agreeableness than SAD. Genetic risk factors for AvPD, compared to SAD, had a weaker positive correlation with genetic factors underlying neuroticism, and a stronger negative correlation with genetic factors underlying extraversion and openness to experience. The genetic liability to AvPD could be fully accounted for by genetic factors influencing SAD and normative personality. AvPD and SAD also differed on the environmental correlations, with a stronger positive correlation with neuroticism and stronger negative correlations with extraversion and openness to experience identified for AvPD. Environmental factors underlying SAD and personality traits fully explained environmental risk for AvPD. AvPD and SAD are differentially related to several personality traits at the phenotypic, genetic, and environmental level, and SAD and personality traits may together account for the genetic and environmental liability to AvPD.