The structure of genetic and environmental risk factors for DSM-IV personality disorders: a multivariate twin study.
BACKGROUND
Although both genetic and environmental factors affect risk of individual personality disorders (PDs), we know little of how they contribute to the pattern of comorbidity between the PDs in the Diagnostic and Statistical Manual of Mental Disorders (Fourth Edition) (DSM-IV).


OBJECTIVE
To clarify the structure of the genetic and environmental risk factors for the 10 DSM-IV PDs.


METHODS
Assessment of PDs at personal interview and multivariate twin modeling with the Mx program.


METHODS
General community.


METHODS
A total of 2794 young adult members of the Norwegian Institute of Public Health Twin Panel. Main Outcome Measure Number of endorsed criteria for the 10 DSM-IV PDs.


RESULTS
The best-fit multivariate twin model required 3 genetic and 3 individual-specific environmental factors and genetic and individual-specific factors unique to each PD. The first genetic factor had high loadings on PDs from all 3 clusters including paranoid, histrionic, borderline, narcissistic, dependent, and obsessive-compulsive. The second genetic factor had substantial loadings only on borderline and antisocial PD. The third genetic factor had high loadings only on schizoid and avoidant PD. Several PDs had substantial disorder-specific genetic risk factors. The first, second, and third individual-specific environmental factors had high loadings on the cluster B, A, and C PDs, respectively, with 1 exception: obsessive-compulsive PD loaded with cluster B and not cluster C PDs.


CONCLUSIONS
Genetic risk factors for DSM-IV PDs do not reflect the cluster A, B, and C typology. Rather, 1 genetic factor reflects a broad vulnerability to PD pathology and/or negative emotionality. The 2 other genetic factors are more specific and reflect high impulsivity/low agreeableness and introversion. Unexpectedly, the cluster A, B, and C typology is well reflected in the structure of environmental risk factors, suggesting that environmental experiences may be responsible for the tendency of cluster A, B, and C PDs to co-occur.
Kendler
Kenneth S
KS
Virginia Institute for Psychiatric and Behavioral Genetics, Virginia Commonwealth University, PO Box 980126, Richmond, VA 23298-0126, USA. kendler@vcu.edu
Aggen
Steven H
SH
Czajkowski
Nikolai
N
Røysamb
Espen
E
Tambs
Kristian
K
Torgersen
Svenn
S
Neale
Michael C
MC
Reichborn-Kjennerud
Ted
T
D000328:Adult; D002391:Catchment Area, Health; D039721:Diagnostic and Statistical Manual of Mental Disorders; D005260:Female; D006801:Humans; D007406:Interview, Psychological; D008297:Male; D009664:Norway / Q000453:epidemiology; D010554:Personality Disorders / Q000175:diagnosis / Q000235:genetics; D015995:Prevalence; D012307:Risk Factors; D012931:Social Environment; D014427:Twins / Q000235:genetics*