According to a study published in Personality and Individual Differences, adults with harsher childhoods demonstrate a higher white blood cell count, and the effect is partly explained by higher levels of narcissism. The study’s authors suggest that an unstable upbringing paves the way for the development of narcissistic traits, which then leads to risk-taking behavior, finally triggering an elevated immune system response in order to combat stress.
Childhood stress has been found to trigger an immune system response that mirrors the body’s reaction to physical stress. This response involves an increased production of white blood cells (WBC) to protect the body from infection. A research team led by Yaoguo Geng was interested in whether personality might magnify this relation between childhood adversity and immune system response.
Geng and team note that people who live in unpredictable environments often develop what scholars call a fast life history strategy. People with this mindset tend to focus on the short-term, prioritize a higher number of sexual partners, and invest less in offspring. This higher number of sexual partners puts individuals at greater risk of encountering pathogens, which may trigger an elevated immune system response. Because the dark personality traits of narcissism, Machiavellianism, and psychopathy have been associated with a fast life history strategy, Geng and colleagues proposed that these traits may play a role in the link between childhood adversity and WBC count.
A total of 234 Chinese adults between the ages of 18 and 55 completed a questionnaire that included assessments of the Dark Triad traits and life history speed. To assess childhood adversity, the surveys asked participants to respond to seven items assessing childhood exposure to violence and seven items assessing the unpredictability of one’s childhood environment. The participants also had blood samples drawn to measure their white blood cell count.
The results revealed that childhood exposure to violence was associated with a higher WBC count, suggesting that stressful events in childhood can negatively impact the nervous, endocrine, and immune systems. Adults with a more unpredictable childhood and with greater exposure to violence in childhood were also more likely to have a fast life history strategy, and in turn, higher psychopathy and Machiavellianism.
Further analysis revealed that only one variable was directly related to white blood cell count — narcissism. Participants with higher narcissism demonstrated increased WBC. Furthermore, childhood adversity was indirectly related to WBC through narcissism. This suggested that participants growing up in a more unstable environment were more likely to develop narcissistic traits, and in turn, an elevated immune response characterized by an increased production of white blood cells. A possibility is that narcissistic tendencies lead to risk-taking behavior, like casual sex and substance abuse, that then triggers an increased immune response to fight the stress.
Interestingly, this mediating role of narcissism on the relationship between childhood adversity and white blood cell count was stronger among women than men. This suggests that women are more likely to experience an increased immune response after acting on narcissistic tendencies, perhaps because women tend to be more affected by socio-ecological conditions than men. However, overall, men were more likely to have a fast life history strategy, dark personality traits, more violent childhoods, and increased WBC.
Geng and colleagues say that their study was limited given that it only included retrospective accounts of childhood experiences and relied on participant recall. The study also did not include a measure of childhood health problems, which may play a role in increased immune system responses.
The study, “Childhood adversity is associated with adulthood white blood cell count through narcissism”, was authored by Yaoguo Geng, Xueying Sai, Peter K. Jonason, Minqi Yang, Xueli Zhu, Jingjing Gu, and Huijuan Kong.