Irritable mood and behavioral response to threat: Investigating the behavioral correlates of irritability in an experimental model of pregnancy hormone changes

Irritability is a pervasive yet underrecognized feature of perinatal distress and can have a profound impact on maternal wellbeing. Recent experimental studies demonstrate that the hormonal changes of pregnancy can robustly trigger the onset and exacerbation of irritable mood in at-risk individuals. However, more work is needed to explore how these mood changes impact behavior. The current study therefore investigates the behavioral correlates of irritability in the context of an experimentally controlled hormonal model of pregnancy. The hormone state of pregnancy was simulated in non-pregnant women with a history of postpartum depression (PPD; n = 11) and healthy controls (n = 12) by inducing hypogonadism and then adding back supraphysiologic doses of estradiol and progesterone for 2 weeks ("addback"). The Point Subtraction Aggression Paradigm (PSAP), a behavioral task of relational aggression, was administered at baseline and hormone addback. In the task, participants press buttons to accrue money, subtract money from a fictional opponent at no direct gain to themselves ("steal" press), or temporarily protect money from their opponent ("protect" press). Increased irritable mood at hormone addback was not associated with steal presses but was associated with more protect presses relative to opponent provocations. Notably, effect sizes increased after covarying COVID- 19 related stress and PPD history. Women who experienced elevated irritable mood during hormone addback were more likely to protect resources in response to threat. Findings have important implications for understanding the hormonal etiology and behavioral consequences of this ubiquitous yet poorly understood mood symptom.