Personality dimensions as common and broadband-specific features for internalizing and externalizing disorders.

Area of Science:

• Psychiatry
• Behavioral Genetics
• Developmental Psychology

Background:

• Covariation between internalizing and externalizing disorders is complex.
• Temperament and personality traits may explain shared variance.
• Neuroticism and novelty seeking are candidate personality factors.

Purpose of the Study:

• Investigate neuroticism as a common feature of internalizing and externalizing disorders.
• Examine novelty seeking as a specific factor for externalizing disorders.
• Determine the extent to which these traits explain disorder covariance.

Main Methods:

• Utilized a twin study design with 12- to 18-year-old participants.
• Analyzed genetic and nonshared environmental influences on disorder covariation.
• Examined the roles of neuroticism and novelty seeking.

Main Results:

• Neuroticism-related genetic and environmental influences affected covariation across internalizing and externalizing disorders.
• Novelty seeking-related genetic influences impacted externalizing disorder covariation and major depressive disorder-externalizing disorder links.
• After accounting for neuroticism and novelty seeking, no significant additional common influences were found.

Conclusions:

• Neuroticism is a heritable, common factor underlying both internalizing and externalizing disorders.
• Novelty seeking is a heritable factor differentiating anxiety disorders from externalizing disorders.
• Neuroticism and novelty seeking adequately explain the observed covariance among these disorders.