A Swedish Population-Based Multivariate Twin Study of Externalizing Disorders.

Area of Science:

• Psychiatry
• Behavioral Genetics
• Epidemiology

Background:

• Prior interview studies suggest an externalizing spectrum of disorders.
• The utility of objective registry data for detecting this spectrum is unexplored.

Purpose of the Study:

• To determine if an externalizing spectrum of disorders can be identified using objective registry data.
• To investigate the genetic and environmental influences underlying this spectrum.

Main Methods:

• Utilized data from 20,603 Swedish twin pairs.
• Extracted information on drug abuse (DA), criminal behavior (CB), and alcohol use disorders (AUD) from national medical, criminal, and pharmacy records.
• Applied multivariate twin modeling using the OpenMx package.

Main Results:

• A common pathway model indicated a latent liability to externalizing syndromes influenced by both genetic and shared environmental factors.
• Heritability was higher in females (76%) compared to males (62%), while shared environmental influences were stronger in males (23% vs. 3%).
• Drug abuse (DA) was the strongest index of liability, while criminal behavior (CB) was the weakest. Specific genetic and environmental influences were also identified for each disorder.

Conclusions:

• An externalizing spectrum, characterized by shared genetic and environmental influences, was identified in registry data.
• The nature of the externalizing spectrum and its contributing factors differed between sexes.
• The findings support a common liability model for externalizing disorders, with distinct sex-specific patterns of influence.