Dark traits and depression: Study finds psychopathy and Machiavellianism linked to more depressive symptoms

People with certain dark personality traits may be more likely to experience symptoms of depression, according to a new study published in the Journal of Research in Personality. After reviewing data from more than 15,000 participants across 31 studies, researchers found that both psychopathy and Machiavellianism were consistently linked to higher levels of depressive symptoms. Narcissism, however, showed no consistent relationship with depression. The study highlights the need for mental health professionals to consider these darker traits when assessing and treating depression.

The Dark Triad refers to a group of three personality traits—psychopathy, Machiavellianism, and narcissism—that share common features like emotional detachment, self-interest, and a willingness to manipulate others. These traits exist on a spectrum in the general population, not just among those diagnosed with personality disorders.

Previous research on personality and depression has focused mainly on the Five Factor Model, which includes traits like neuroticism and conscientiousness. But some psychologists argue that this model doesn’t fully account for personality traits tied to manipulation, impulsivity, or emotional coldness. That gap has prompted growing interest in the darker side of personality and how it may relate to mental health problems, especially depression.

To better understand how the Dark Triad traits might relate to depression, the researchers conducted a meta-analysis—a type of study that combines data from many separate studies to find overall patterns. This method allows scientists to get a clearer picture of whether an effect holds up across different samples, settings, and measurement tools.

The researchers searched six major databases for studies published in English before June 2024. They included only peer-reviewed studies that reported correlations between the Dark Triad traits and depressive symptoms. After screening more than 5,000 studies, the researchers narrowed their focus to 31 eligible studies with a combined total of 15,567 participants. These studies spanned several regions, including Europe, North America, and Asia.

The researchers looked at how each of the three Dark Triad traits was measured and how depressive symptoms were assessed. For example, psychopathy was commonly measured using the Self-Report Psychopathy Scale, while Machiavellianism was often assessed with the Mach-IV scale. Depression was usually measured using standard tools like the Beck Depression Inventory or the Center for Epidemiologic Studies Depression Scale. Most studies reported their findings using correlation coefficients, which indicate the strength and direction of a relationship between two variables.

Across all studies, psychopathy and Machiavellianism were both linked to higher levels of depressive symptoms. The correlation for psychopathy was moderately strong, suggesting that people who are impulsive, emotionally detached, and prone to antisocial behavior may also be more vulnerable to feelings of sadness, hopelessness, and other depressive symptoms. A similar pattern was found for Machiavellianism, a trait marked by cynicism, manipulation, and distrust of others. Individuals scoring higher in Machiavellianism were also more likely to report experiencing depressive symptoms.

Interestingly, narcissism did not show a significant overall relationship with depression. But the picture became more complex when the researchers looked at how narcissism was measured. Some tools, such as the Short Dark Triad scale, tended to emphasize grandiose narcissism—traits like confidence, dominance, and a need for admiration. These studies showed a weak or even negative association with depression, suggesting that grandiose narcissism might protect against low mood.

Other tools, like the Dirty Dozen scale, may capture more aspects of vulnerable narcissism, which includes insecurity, hypersensitivity to criticism, and emotional fragility. In these cases, narcissism showed a small but significant positive link to depressive symptoms. This suggests that not all forms of narcissism function the same way when it comes to emotional well-being.

The study also found that the way these traits and symptoms were measured had a significant impact on the results. For example, different depression scales varied in how strongly they captured depressive symptoms in people with high levels of psychopathy. Some tools appeared to be more sensitive to the kinds of emotional disturbances experienced by people with dark personality traits, which affected the size of the correlations observed. Similarly, the type of scale used to measure Machiavellianism influenced the strength of its link to depression. This shows that the tools researchers choose can shape the conclusions they reach.

The study does have some limitations. Most importantly, the meta-analysis relied on correlational data, which means it cannot determine whether dark personality traits cause depression, or vice versa. It’s possible that experiencing depressive symptoms over time could also influence how someone scores on these personality measures. The researchers also noted that they could not explore the separate roles of grandiose and vulnerable narcissism in depth, due to limitations in the available data. Additionally, most studies came from Europe, North America, and Asia, leaving a gap in data from other regions like Africa and Oceania.

Even with these limitations, the study adds to growing evidence that the darker sides of personality play a role in mental health. For psychologists, counselors, and other mental health professionals, this means that assessing traits like emotional coldness, manipulation, or impulsivity may be helpful when diagnosing and treating depression.

Looking ahead, the researchers suggest that future studies should include more detailed assessments of narcissism and expand research into underrepresented regions. They also recommend using more comprehensive and nuanced measurement tools to capture the complexity of dark personality traits.

The study, “Dark and Blue: A meta-analysis of the relationship between Dark Triad and depressive symptoms,” was authored by Chunwei Lyu, Danna Xu, and Guo Chen.