Summary by Rachel A Plouffe, PhD
Background
Psychologists have consistently found that psychopathic traits are linked to negative experiences in romantic relationships. Partners of individuals high in these traits often report higher levels of infidelity, emotional and physical abuse, and psychological distress, alongside lower relationship satisfaction.
Despite decades of research, a key question remains: do psychopathic traits actually cause these harmful outcomes for partners, or are these relationship patterns explained by something else, such as shared environments, relationship dynamics, or levels of attachment?
Understanding whether psychopathy is a direct source of lower partner well-being is important. It helps clarify whether these traits are simply linked to relationship problems, or whether they actively contribute to causing them. This reflects a broader challenge in psychological research: determining whether one factor causes another. The strongest way to establish causation is through experiments in which people are randomly assigned to and tested within different groups. However, this is not possible in psychopathy research, as it would be unethical (and unrealistic) to assign individuals to have higher or lower levels of psychopathic traits.
To overcome this challenge, Hissey and colleagues (2025) took advantage of recent developments in causal inference methods to determine whether psychopathy causes lower well-being, self-esteem, life satisfaction, and relationship satisfaction. The authors also wanted to understand whether psychopathy causes higher partner psychological distress and relationship conflict. Basically, these methods allow researchers to estimate probable causal relationships without conducting unethical experiments.
Hissey and colleagues (2025) examined psychopathy as a mix of several components of personality. These include being cold, callous, or lacking empathy (antagonism), remaining calm under stress (emotional stability), acting impulsively and taking risks (disinhibition), and having an inflated sense of self-importance or a need to dominate others (narcissism). In their study, they examined whether psychopathy as a whole, and each of these four components individually, directly affects partners’ experiences in relationships and mental health.
Why was the study done?
As noted, a key challenge in psychopathy research is understanding whether a person’s traits are strong enough on their own to influence their partner’s well-being. Hissey and colleagues (2025) addressed this issue by using a statistical approach designed to separate the effects of each partner in a relationship, allowing them to test how one person’s traits may affect the other person’s well-being.
Importantly, although it might seem reasonable to expect psychopathy to affect many areas of a partner’s well-being, this pattern of findings has not been firmly established in previous research. Instead, studies linking psychopathy to partners’ mental health have usually focused on a limited range of outcomes, such as overall well-being. Hissey and colleagues (2025) included multiple indicators of well-being, including those related to the individual and the relationship itself: personal well-being, psychological distress, self-esteem, life satisfaction, relationship conflict, and relationship satisfaction.
Given these previous research challenges, the authors sought to investigate whether increases in one person’s psychopathic trait levels caused their partners to experience reduced well-being at one-year and five-year follow-ups.
How was the study done?
In the first of two studies, a total of 1,012 participants (506 couples; 49% men; age range = 22 to 90 years) were drawn from three waves of the New Zealand Attitudes and Values Survey (NZAVS), which examined values, attitudes, and health outcomes of New Zealand residents. Of the couples in the study, 425 (84%) were married, and they self-identified as Pākehā/New Zealand European (87%), Māori (7%), Asian (4%), and Pacific peoples (2%). Data associated with the waves used for this study were collected between 2018 and 2021.
In the second study, 1,832 participants (916 couples; 49% men; age range = 19 to 90 years) were drawn from six waves of the NZAVS collected between 2018 and 2024. Like the first study, most were married (78%), and most self-identified as Pākehā/New Zealand European (84%), followed by Māori (9%), Asian (5%), and Pacific peoples (2%).
Across both studies, psychopathy scores at the first wave were used as the starting point (baseline). Any changes in psychopathy were then tracked in later waves, and these increases over time were examined in relation to psychological outcomes measured at the final wave, such as distress.
Participants completed questionnaires reflecting psychopathy and different aspects of well-being. The authors used a modified version of a statistical approach often used with romantic couples to determine whether changes in psychopathy over one year (and four years) cause significant changes over time in partner well-being, psychological distress, self-esteem, life satisfaction, relationship conflict, and relationship satisfaction.
What did the researchers find?
In the first of two studies, Hissey and colleagues (2025) set out to test whether increases in psychopathy over one year resulted in subsequent decreases in partner well-being, self-esteem, life satisfaction, and relationship satisfaction, and increases in partner anxiety, depression, psychological distress, and relationship conflict. The researchers found that, when the psychopathy scores of one member of the couple increased by one point over a year, their partners’ anxiety and perceptions of relationship conflict also increased over the year. Unexpectedly, however, increases in psychopathic traits also caused increases in partners’ self-esteem, on average. In addition, the specific components of psychopathy – antagonism, disinhibition, emotional stability, and narcissism – did not produce meaningful changes in partners’ well-being components or in their relationship satisfaction.
In their second study, the authors adapted VanderWeele et al.’s (2020) design for causal investigations of multi-dimensional well-being. They found that, over four years, increases in psychopathy scores probably caused partners to experience worsened well-being and self-esteem, reduced relationship satisfaction, and greater psychological distress, depression, and relationship conflict in the fifth year. When individual components of psychopathy were examined, the results differed from those reported in the first study. Specifically, increases in antagonism resulted in higher partner perceptions of relationship conflict, as well as lower well-being and life satisfaction. Higher levels of disinhibition over time resulted in lower partner relationship satisfaction, well-being, and life satisfaction. Increases in narcissism over time resulted in greater depression for partners, as well as reductions in partner self-esteem. Increases in emotional stability, however, were more protective in nature, resulting in lower partner psychological distress, depression, and anxiety, and higher partner life satisfaction.
What does this mean?
For decades, psychologists have tried to figure out how having psychopathic traits might affect the well-being of someone’s romantic partner. However, it has not been clear whether these traits cause the partner to feel worse, or if the lower well-being is really due to something else, such as stress, conflict or other personal factors. In this research, however, Hissey and colleagues (2025) found clear evidence that psychopathy appears to play a direct role in lowering a partner’s well-being.
When people’s psychopathy levels increased over the course of a year, their partners became more anxious and felt like there was more conflict in the relationship. This supports earlier research showing that higher psychopathy in one partner is linked to greater anxiety in the other partner. However, something surprising also showed up: their partners’ self-esteem actually increased after one year. The researchers suggested this increase might be because people with higher psychopathy can come across as charming, attractive, and confident, often seeming powerful or of high status. Because of this, their partners may initially feel special, chosen, or validated by being with them, which can boost their self-esteem, at least in the short term. In the long term, however, this increase in self-esteem did not remain. In a later follow-up over six waves, the researchers found the opposite effect. Specifically, partners no longer showed these increases in self-esteem, and instead experienced declines in self-esteem. This finding suggests that any initial boost in self-esteem may be temporary and does not persist over time.
Contrary to expectation, the individual traits linked to psychopathy, such as being antagonistic, impulsive, emotionally stable, and narcissistic, do not seem to significantly harm a partner’s well-being over a shorter period of one year. This suggests that looking at these traits in isolation may not fully capture their impact. Instead, psychopathy appears to be more influential when considered as a whole pattern of personality.
Over a longer period of four years, however, clearer negative effects begin to emerge. People with higher levels of psychopathy tend to have partners who report lower self-esteem, reduced well-being, and less satisfaction in their relationships. The most noticeable change over time was an increase in relationship conflict, suggesting that the effects of psychopathy build gradually and become more damaging.
When looking at specific traits over this longer period, some patterns stand out. For example, antagonism led to greater conflict and lower life satisfaction, while narcissism caused reduced self-esteem and higher levels of depression in partners.
Overall, the findings suggest that psychopathy may operate as a combination of characteristics that together create harm in relationships. When a person displays more of these traits, there will be a greater negative impact on their partner’s well-being over time.
What are the strengths and limitations of this research?
This study is one of the first to track how psychopathy affects romantic partners over time, rather than just taking a single snapshot. By following couples across several years in a New Zealand sample and using robust statistical methods, the researchers were able to better understand how one partner’s psychopathy causes changes in their partners’ well-being. The study also looked at a wide range of outcomes, including self-esteem, relationship satisfaction, conflict, and mental health, which provides a more complete picture of how individuals may be affected by their partners’ psychopathic traits.
However, there are some limitations to keep in mind. The findings are based on self-reported data, meaning participants described their own experiences, and these self-reports may not accurately map onto clinical psychopathy assessments. In addition, this approach to assessing psychopathy can sometimes be influenced by memory, or bias if the person wishes to present themselves in a particular way to the researcher. Lastly, because the study was conducted in New Zealand, the results may not fully apply to people in other countries or cultural contexts.
Overall, this research provides evidence that rising levels of psychopathy caused declines in partner well-being over time, extending past research that has found that psychopathy and well-being are related at a single time point. The differing short- and long-term findings suggest that these effects are not static but fluctuate across time. By following couples across several years, this study provides a clearer picture of how psychopathic traits can affect partners and relationships in the long term.
Article reviewed:
Hissey, A., Eisenbarth, H., Hammond, M., Sibley, C. G., & Bulbulia, J. (2025). Causal Effect of Psychopathy on Partner Well‐Being: A National Longitudinal Study. Journal of Personality. https://doi.org/10.1111/jopy.70042
Information about the NZAVS:
Sibley, C. G. (2009-2025) Sampling procedure and sample details for the New Zealand Attitudes and Values Study. https://osf.io/75snb/wiki/Sample Details/
Additional Reference:
VanderWeele, T. J., Mathur, M. B., & Chen, Y. (2020). Outcome-wide longitudinal designs for causal inference: a new template for empirical studies. Statistical Science, 35(3), 437-466. https://doi.org/10.1214/19-STS728
