Personality traits such as neuroticism and introversion are important predictors of depression across the lifespan, according to research published in Journal of Affective Disorders.
Depression remains one of the leading causes of disability worldwide. Although depression is often characterized by a variety of symptoms that vary greatly between individuals, one consistent factor appears to be the role of personality traits. Previous research has shown that certain personality traits, such as high neuroticism and low conscientiousness, are associated with an increased risk of both depression and anxiety. However, many studies have either focused exclusively on one personality dimension at a time or have not examined potential changes in these relationships at different stages of life.
Zhen Yang and colleagues sought to build on this work by examining the relationship between personality traits and depressive and anxiety symptoms across the lifespan.
The researchers used data from the Nathan Kline Institute Rockland Sample (NKI-RS), a large community-based dataset that includes individuals from a variety of age groups, from adolescence to older adulthood. The final sample consisted of 1,494 participants between the ages of 12 and 85. Participants were divided into four groups: those with depression alone, those with anxiety alone, individuals with both depression and anxiety, and a healthy control group without mental illness.
Psychiatric diagnoses for participants were determined using structured clinical interviews: the Kiddie Schedule for Affective Disorders and Schizophrenia (K-SADS) for participants aged 6 to 17 years and the Structured Clinical Interview for DSM-IV Axis I Disorders (SCID-I/NP) for those who are between the ages of 18 and 85.
In the study, personality traits were assessed using the NEO Five-Factor Inventory (NEO-FFI), which assesses five main dimensions of personality: neuroticism, extroversion, openness to experience, agreeableness, and conscientiousness. The researchers also collected a variety of psychological and physical measurements, including cognitive tasks, eating behavior questionnaires, and physiological assessments such as heart rate and body mass index (BMI).
Individuals with depression or anxiety were found to have higher levels of neuroticism and lower levels of extraversion compared to healthy controls. This pattern was particularly pronounced in subjects with co-morbid depression and anxiety, who showed an even more vulnerable personality profile characterized by high levels of neuroticism and higher levels of introversion. During adolescence, depression was associated with higher neuroticism and lower extraversion, agreeableness, and conscientiousness. Adolescent anxiety, however, was associated with higher levels of neuroticism and conscientiousness.
In adulthood, the relationship between personality traits and mental health symptoms appeared to change. Depression was no longer significantly associated with any personality trait after controlling for anxiety, suggesting that other factors, such as life stressors or biological changes, may play a more prominent role in influencing depression in adults.
However, anxiety remained strongly associated with neuroticism and was negatively related to extraversion, agreeableness, and conscientiousness, suggesting that more introverted, disaffected, and conscientious individuals are more likely to experience anxiety symptoms in adulthood.
In adulthood, depression continued to show no significant correlations with personality traits, while anxiety remained associated with neuroticism and, uniquely in this age group, with agreeableness and openness to experience.
The machine learning model achieved 70% predictive accuracy for depression, with neuroticism and introversion being the most important predictors of depression. It further highlighted that higher BMI, lower heart rate during exercise and certain eating behaviours, such as increased inhibition and hunger perception, were also important factors contributing to the likelihood of depression. These findings suggest that a combination of personality traits, physical health indicators, and lifestyle behaviors can actually predict depression.
Of note, the cross-sectional design of the study limits the ability to draw causal inferences about the relationship between personality traits and depression.
The study, “Personality Traits as Predictors of Lifetime Depression,” was written by Zhen Yang, Allison Li, Chloe Roske, Nolan Alexander, and Vilma Gabbay.
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