Childhood adversity is associated with adulthood white blood cell count through narcissism

The immune system's response to threat is to amass protective white blood cells. We investigated (N = 234) individual differences in white blood cell (WBC) through the lens of life history theory by examining individual differences in (self-reported) childhood threats (i.e., unpredictability and harshness), life history speed, and the Dark Triad traits (i.e., Machiavellianism, narcissism, and psychopathy). People with adverse childhood conditions had faster life history strategies and higher Dark Triad traits, and were more prone to be inflamed (i.e., sexually transmitted infections). In addition, men reported more childhood harshness, Machiavellianism, psychopathy, and a faster life history strategy and a higher WBC count than women did. Moreover, we revealed, through structural equation models, that the effects of childhood adversity on adult WBC count were mediated by narcissism especially in women. Results are discussed in terms of the mechanism underlying the association between childhood environments and physiological health.