Irritability and anger: Insights From Non-Clinical Samples and Patients with Premenstrual Dysphoria

Abstract

Feelings of irritability or anger are common experiences, both in healthy individuals and in those with pathological conditions. However, the explication and operationalization of the differences and similarities between irritability and anger in research and clinical settings are inadequate and confounded. The overall aim of this thesis was to advance the scientific comprehension of irritability and anger in both a non-clinical population and in individuals experiencing severe premenstrual irritability and anger. The four included studies involve self-report measures of irritability and anger, examining their internal relationships as well as associations with both self-reported and behaviorally assessed impulsivity and aggression. Study I (N = 471) evaluated the empirical relationship between irritability and anger and explored how they interact with various forms of impulsivity in a non-clinical sample. The findings suggest that emotion-related impulsivity (urgency) might influence the threshold at which internally experienced irritability transforms into outwardly expressed anger. Study II (N = 143) investigated whether behavioral measures in a laboratory aggression test (the Anger-Infused Ultimatum Game) are sensitive to variations in self-reported irritability and trait anger in a non-clinical sample. Results showed that, while trait anger was positively associated with reactive aggression, irritability was not. The final two studies were based on data from a randomized, placebo-controlled crossover trial evaluating the effects of SSRI (escitalopram) treatment in a group of naturally cycling women with severe premenstrual irritability and anger. In Study III (N = 34), while irritability/anger was reduced as a result of escitalopram treatment (vs. placebo), no effect of escitalopram on reactive aggression was found in the Point Subtraction Aggression Paradigm. Escitalopram did influence aggression in the Anger-Infused Ultimatum Game, but only for individuals whose outward (but not inward) expressions of anger were markedly elevated in the symptomatic phase of the menstrual cycle. In Study IV (N = 27), a beneficial effect of escitalopram treatment (vs. placebo) was found in some aspects of impulsivity and inattentiveness as measured using the Conners Continuous Performance Test (3rd Edition). Furthermore, emotion-related impulsivity (urgency) was found to significantly increase in the luteal (vs. follicular) phase in the absence of escitalopram treatment. Based on the findings of the four studies, the thesis demonstrates that irritability and anger have distinct explanatory importance, which enhances our understanding of individual variations in emotional experiences. Moreover, the findings enhance the comprehension of the behavioral consequences of SSRI treatment for premenstrual irritability/anger and provide additional insight into the role of impulsivity throughout the menstrual cycle. These insights have both theoretical and clinical implications.