A study conducted on university students found that individuals with higher levels of primary psychopathic traits tend to have lower baseline cortisol levels in the morning, but not in the afternoon. This effect did not depend on participants’ sex. The research was published in Social Neuroscience.
Psychopathic traits are personality characteristics involving callousness, lack of empathy and remorse, manipulativeness, shallow affect, and a tendency toward impulsive or antisocial behavior. They are commonly divided into primary and secondary psychopathy.
Primary psychopathy is characterized by low anxiety, emotional coldness, lack of empathy, superficial charm, and reduced fear responsiveness. Individuals high in primary psychopathy tend to be manipulative, callous, and emotionally detached. These traits are thought to primarily depend on genetics and temperament.
Secondary psychopathy is characterized by impulsivity, emotional instability, hostility, and high negative affect. Individuals high in secondary psychopathy frequently show reactive aggression, poor emotional regulation, and heightened sensitivity to stress. Secondary psychopathy is more strongly associated with adverse environmental influences, such as trauma or an unstable upbringing.
Study author Todd A. Armstrong and his colleagues wanted to explore the associations between testosterone, cortisol, and psychopathic traits. They hypothesized that psychopathic traits would be associated with higher testosterone levels when cortisol is high. They also expected higher testosterone levels to be associated with higher levels of secondary psychopathy, while lower levels of cortisol would be associated with higher levels of primary psychopathic traits.
Data for their study were collected as part of a project exploring biological influences on traits associated with antisocial and criminal behavior. Study participants were 552 undergraduate students from a university in the southern United States. Of these, 366 participants were women. Their average age was 20 years.
Study participants completed assessments of primary and secondary psychopathic traits (the Levenson Self-Report Psychopathy Scale and the Inventory of Callous Unemotional Traits). They then reported to a laboratory where they gave saliva samples allowing the study authors to estimate their cortisol and testosterone levels.
As there were many students, the laboratory samples were taken between 08:00 in the morning and 18:30 in the evening. This allowed the study authors to look at cortisol and testosterone levels at different times of day. In the laboratory, study participants completed a short social stressor speech task.
In this task (which was designed to induce stress), participants were given 2 minutes to prepare a speech in which they would address their greatest strengths and weaknesses. They would then record their 2-minute speech. Saliva samples were collected before and after this task, allowing researchers to measure both baseline hormone levels (before the speech task) and their levels when the participant was stressed (i.e., after the speech task).
Cortisol is a hormone released by the adrenal glands that plays a central role in the stress response by mobilizing energy and regulating metabolism, immune function, and arousal. Testosterone is a steroid hormone primarily produced by the testes (and in smaller amounts by the ovaries and adrenal glands) that influences sexual development, muscle mass, dominance-related behavior, and aspects of motivation and risk-taking.
Results showed that individuals with more pronounced primary psychopathic traits tended to have lower baseline cortisol levels (i.e., levels before the speech task). However, this association was present in the morning only and absent in the afternoon. The observed association between primary psychopathic traits and cortisol did not depend on participants’ sex.
“The current results join a small group of studies that indicate a role for hormones in the explanation of variation in psychopathy. While recent work in this area has emphasized interactions between testosterone and cortisol, the current results suggest that direct associations between cortisol and psychopathic traits may be central to our understanding of associations between hormones and psychopathy,” the study authors concluded.
The study contributes to the scientific understanding of biochemical correlates of psychopathy. However, it should be noted that the study was conducted on university students, a population in which the overall levels of psychopathic traits are generally very low. Results in groups with greater variability in psychopathic traits might differ.
The paper, “Testosterone, cortisol, and psychopathy: Further evidence with the Levenson self-report psychopathy scale and the inventory of callous unemotional traits,” was authored by Todd A. Armstrong, Danielle L. Boisvert, Jessica Wells, Richard H. Lewis, Eric M. Cooke, Matthias Woeckener, Nicholas Kavish, and James M. Harper.