A longitudinal twin study of cluster A personality disorders. Issue 7 (14th November 2014)

• Record Type: Journal Article
• Authors: Kendler, K. S.; Aggen, S. H.; Neale, M. C.; Knudsen, G. P.; Krueger, R. F.; Tambs, K.; Czajkowski, N.; Ystrom, E.; Ørstavik, R. E.; Reichborn-Kjennerud, T.
• Is Part Of: Psychological medicine. Volume 45:Issue 7(2015)
• Page Start: 1531
• Page End: 1538
• Publication Date: 2014-11-14
• Subjects: Cluster A personality disorders, -- longitudinal studies, -- paranoid personality disorder, -- personality disorders, -- schizotypal personality disorder; Psychiatry -- Periodicals; Medicine and psychology -- Periodicals; Clinical psychology -- Periodicals; 616.89
• DOI: 10.1017/S0033291714002669
• Languages: English
• ISSNs: 0033-2917

Abstract

Abstract : Background: While cluster A personality disorders (PDs) have been shown to be moderately heritable, we know little about the temporal stability of these genetic risk factors. Method: Paranoid PD (PPD) and schizotypal PD (STPD) were assessed using the Structured Interview for DSM-IV Personality in 2793 young adult twins from the Norwegian Institute of Public Health Twin Panel at wave 1 and 2282 twins on average 10 years later at wave 2. Using the program Mx, we fitted a longitudinal latent factor model using the number of endorsed criteria for PPD and STPD. Results: The stability over time of the criteria counts for PPD and STPD, estimated as polychoric correlations, were +0.34 and +0.40, respectively. The best-fit longitudinal model included only additive genetic and individual-specific environmental factors with parameter estimates constrained to equality across the two waves. The cross-wave genetic and individual-specific environmental correlations for a latent cluster A factor were estimated to equal +1.00 and +0.13, respectively. The cross-time correlations for genetic and environmental effects specific to the individual PDs were estimated at +1.00 and +0.16–0.20, respectively. We found that 68% and 71% of the temporal stability of PPD and STPD derived, respectively, from the effect of genetic factors. Conclusion: Shared genetic risk factors for two of the cluster A PDs are highly stable in adults over a 10-year period while environmental risk factors are relatively transient. Over two-thirds of the long-term stability of the common cluster A PD liability can be attributed to genetic influences.