The relationship between personality throughout adolescence and social anxiety disorder in young adulthood. A longitudinal twin study.

This study examined the longitudinal relationship between a range of personality related variables measured throughout adolescence, and social anxiety disorder (SAD) in young adulthood. In addition, we examined to what degree the phenotypic associations between personality and SAD could be attributed to shared genetic and environmental factors, respectively. A total of 3394 twins (56% females), consisting of seven national birth cohorts from Norway, participated in the study. Personality was measured with self-report questionnaires at three times throughout adolescence, and SAD was measured with a diagnostic interview in early adulthood (M = 19.1 years, SD = 1.2). Correlation and regression analyses were performed to examine phenotypic associations between personality and SAD. We then created four composite scores of personality, in which the personality variables from four different ages throughout adolescence were weighted relative to their importance for SAD. Finally, a series of Cholesky decomposition models were used to examine the underlying genetic and environmental influences on the phenotypic associations between composite scores of personality and SAD. The results showed that especially higher neuroticism, lower extraversion, higher levels of loneliness, and lower levels of resilience, self-efficacy and sense of coherence, were associated with SAD. The phenotypic correlations between composite scores of personality and SAD increased from 0.42 when personality was measured 6-7 years prior to the assessment of SAD, to 0.52 when personality was measured shortly before the assessment of SAD. These phenotypic associations were mainly due to genetic influences, indicating that personality in adolescence predicts SAD in early adulthood due to shared genetic influences rather than having direct 'causal' effects on SAD.