Personality and major depression: a Swedish longitudinal, population-based twin study

Area of Science:

• Psychiatry
• Behavioral Genetics
• Epidemiology

Background:

• Prior research suggests links between neuroticism, extroversion, and major depression (MD) liability.
• Understanding these personality trait associations is crucial for predicting MD risk.

Purpose of the Study:

• To determine the strength and nature of the relationship between neuroticism, extroversion, and the risk of developing major depression.
• To elucidate the underlying genetic and environmental factors contributing to these associations.

Main Methods:

• Longitudinal population-based cohort study utilizing the Swedish Twin Registry.
• Involved 20,692 same-sex twin pairs assessed for personality traits and lifetime history of major depression.
• Employed twin modeling to analyze genetic and environmental influences.

Main Results:

• High levels of neuroticism significantly predicted both lifetime and new-onset major depression.
• Twin analyses revealed that the neuroticism-MD association is primarily driven by shared genetic factors (genetic correlation of +0.46 to +0.47).
• Extroversion showed a weak inverse association with MD risk, which became non-significant after controlling for neuroticism.

Conclusions:

• Neuroticism is a strong indicator of genetic liability to major depression.
• The observed association between neuroticism and major depression is largely attributable to shared genetic risk.
• Extroversion has a limited, independent role in the risk for major depression.