Response to “Hormonal Correlates of Pathogen Disgust: Testing the Compensatory Prophylaxis Hypothesis”

Disgust as a primary emotional system and its clinical relevance

This paper advocates for considering disgust as a primary emotional system within Panksepp's Affective Neuroscience framework, which has the potential to improve the efficacy of psychotherapy with obsessive-compulsive disorder, hypochondriasis, and emetophobia. In 2007, Toronchuk and Ellis provided comprehensive evidence that DISGUST system, as they defined it, matched all Panksepp's criteria for a primary emotional system. A debate ensued and was not unambiguously resolved. This paper is an attempt to resume this discussion and supplement it with the data that accumulated since then on DISGUST's relationship with the immune system and the role of DISGUST dysregulation in psychopathology. We hope that renewed research interest in DISGUST has the potential to improve clinical efficacy with hard-to-treat conditions.

Influence of female sex hormones on proactive behavioral and physiological immune parameters

Women may be more susceptible to infections in the luteal phase, supposedly as a consequence of the hormone progesterone and its immunosuppressive action. While immunosuppression may be important for successful oocyte implantation and pregnancy, it makes women more vulnerable to pathogens. According to theory, to compensate for reduced immunocompetence, women in the luteal phase exhibit proactive behavioral responses, such as disgust and avoidance of disease-associated stimuli, to minimize contagion risk. However, previous studies yielded inconsistent results, and did not account for accompanying proactive immune responses, like the increase of secretory immunoglobin A (sIgA). Here, we assessed the proactive immune response and feelings of disgust associated with disease cues in the comparison of 61 woman with a natural menstrual cycle (31 in the follicular and 30 in the luteal phase) and 20 women taking hormonal contraception (HC). Women rated disease vulnerability and disgust propensity, watched a video displaying people with respiratory symptoms, which was evaluated for its disgust-evoking potential and contagiousness, and provided saliva samples for hormone and sIgA analysis. Women with HC reported a heightened vulnerability to disease compared to naturally cycling women, whereas both the feeling of disgust and the sIgA increase elicited by the disease video were similar across groups, regardless of progesterone. We found a u-shaped relationship between progesterone and baseline sIgA in naturally cycling women, with its nadir during ovulation. Overall, our data do not support a compensatory relationship between the proposed progesterone-induced immunosuppression and heightened disgust or a proactive sIgA response.

Pandemic elevates sensitivity to moral disgust but not pathogen disgust

The behavioral immune system, with disgust as its motivational part, serves as the first line of defense in organisms' protection against pathogens. Laboratory studies indicate that disgust sensitivity adaptively adjusts to simulated environmental threat, but whether disgust levels similarly change in response to real-life threats, such as a pandemic, remains largely unknown. In a preregistered within-subject study, we tested whether the threat posed by the Covid-19 pandemic would lead to increased perceived disgust. The perception of threat was induced by testing during two phases of the Covid-19 pandemic (periods of high vs. low pathogen threat). We found heightened levels of moral disgust during a "wave" of the pandemic, but the effect was not observed in the domain of pathogen or sexual disgust. Moreover, the age of respondents and levels of trait anxiety were positively associated with pathogen and moral disgust, suggesting that variation in disgust sensitivity may be based chiefly on stable characteristics.

Associations between nausea and vomiting in pregnancy, disgust sensitivity, and first-trimester maternal serum free β-hCG and PAPP-A

Elevated levels of nausea and vomiting in pregnancy (NVP) and disgust sensitivity have been observed in the first trimester and both are thought to have a protective function for the mother and her fetus. Their aetiology is not clear, however, with previous studies attributing elevated NVP and disgust to various factors including endocrine changes, immunological changes, and psychological variables. To date, no study has directly assessed the relationship between disgust and NVP. Here, we prospectively collected two independent samples (S1 and S2; n₁ = 201, n₂ = 391) of women in the first trimester of pregnancy, who completed the Index of Nausea, Vomiting, and Retching and the Disgust Scale-Revised. We also measured free β-human chorionic gonadotropin (hCG) and pregnancy-associated plasma protein A (PAPP-A) in maternal serum. Our results did not confirm any association between NVP and disgust; in addition, they indicate that NVP and disgust may have different proximate causes. Disgust sensitivity was significantly negatively correlated with free β-hCG and (only in S1) with PAPP-A. In contrast, NVP was significantly positively associated with free β-hCG levels and (only in S1) with PAPP-A. While low hCG levels seem to be an important indicator for activation of the behavioral immune system in the first trimester, increased hCG levels play a role in stronger symptoms of NVP, a result consistent with previous studies. Levels of PAPP-A are likely part of a larger network of immunological and endocrine responses and do not appear to provide sufficient information for predicting women's NVP and disgust sensitivity.

Hormones, ovulatory cycle phase and pathogen disgust: A longitudinal investigation of the Compensatory Prophylaxis Hypothesis

Multiple studies have argued that disgust, especially pathogen disgust and contamination sensitivity, change across women's ovulatory cycle, with higher levels in the luteal phase due to an increase in progesterone levels. According to the Compensatory Prophylaxis Hypothesis (CPH), women have a higher disgust sensitivity to pathogen cues when in the luteal phase (or when progesterone levels are higher), because progesterone is associated with suppressed immune responses. Evidence for this hypothesis is rather mixed and uncertain, as the largest study conducted so far reported no compelling evidence for an association between progesterone levels and pathogen disgust. Further, ovulatory cycle research has been criticized for methodological shortcomings, such as invalid cycle phase estimates, no direct hormone assessments, small sample sizes or between-subjects studies. To address these issues and to contribute to the literature, we employed a large, within-subjects design (N = 257 with four sessions each), assessments of salivary hormone levels and cycle phase estimates based on luteinizing hormone tests. A variety of multilevel models suggest no compelling evidence that self-reported pathogen disgust or contamination sensitivity is upregulated in the luteal phase or tracks changes in women's hormone levels. We further found no compelling evidence for between-subjects associations of pathogen disgust or contamination sensitivity and hormone levels. Results remain robust across different analytical decisions (e.g. in a subsample of women reporting feeling sick). We discuss explanations for our results, limitations of the current study and provide directions for future research.

Disgust Sensitivity Among Women During the COVID-19 Outbreak

The emotion of disgust is suggested to be an adaptation that evolved to keep us away from sources of infection. Therefore, individuals from populations with greater pathogen stress should have a greater disgust sensitivity. However, current evidence for a positive relationship between disgust sensitivity and the intensity of infectious diseases in the environment is limited. We tested whether disgust and contamination sensitivity changed in response to the COVID-19 pandemic. Disgust was assessed in 984 women in 2017 (before pandemic) and 633 women in 2020 (during pandemic) by a set of photographs depicting sources of infection and Pathogen and Moral of Three-Domain Disgust Scale. Further, contamination sensitivity among participants in two waves was measured by Contamination Obsessions and Washing Compulsions Subscale of Padua Inventory. State anxiety was measured with the Polish adaptation of the State-Trait Anxiety Inventory (STAI) only during the second wave of data collection. Women from the COVID-19 pandemic group assessed the photographs depicting sources of infection as more disgusting, scoring higher on Padua Inventory, but lower on Moral Disgust Domain as compared to women from before the pandemic. In addition, anxiety levels during pandemic positively correlated with scores from Pathogen Disgust Domain, Padua Inventory, and the ratings of the photographs. The participants of the study scored higher in state anxiety than the norms determined for the Polish population. Summarizing, we present evidence for differences in individual levels of disgust sensitivity in relation to pathogen stress, supporting the idea that disgust evolved to serve as protection from pathogens.

Differential effects of progesterone on social recognition and the avoidance of pathogen threat by female mice

Although pathogen threat affects social and sexual responses across species, relatively little is known about the underlying neuroendocrine mechanisms. Progesterone has been speculated to be involved in the mediation of pathogen disgust in women, though with mixed experimental support. Here we considered the effects of acute progesterone on the disgust-like avoidance responses of female mice to pathogen threat. Estrous female mice discriminated and avoided the urinary and associated odors of males subclinically infected with the murine nematode parasite, Heligmosomoides polygyrus. These avoidance responses were not significantly affected by pre-treatment with progesterone. Likewise, brief (1 min) exposure to the odors of infected males attenuated the subsequent responses of females to the odors of the normally preferred unfamiliar males and enhanced their preferences for familiar males. Neither progesterone nor allopregnanolone, a central neurosteroid metabolite of progesterone, had any significant effects on the avoidance of unfamiliar males elicited by pre-exposure to a parasitized male. Progesterone and allopregnanolone, did, however, significantly attenuate the typical preferences of estrous females for unfamiliar uninfected males, suggestive of effects on social recognition. These findings with mice indicate that progesterone may have minimal effects on the responses to specific parasite threat and the expression of pathogen disgust but may influence more general social recognition and preferences.

Preregistered Direct Replication of "Sick Body, Vigilant Mind: The Biological Immune System Activates the Behavioral Immune System"

The tendency to attend to and avoid cues to pathogens varies across individuals and contexts. Researchers have proposed that this variation is partially driven by immunological vulnerability to infection, though support for this hypothesis is equivocal. One key piece of evidence (Miller & Maner, 2011) shows that participants who have recently been ill—and hence may have a reduced ability to combat subsequent infection—allocate more attention to faces with infectious-disease cues than do participants who have not recently been ill. The current article describes a direct replication of this study using a sample of 402 individuals from the University of Michigan, the University of Glasgow, and Vrije Universiteit Amsterdam—more than 4 times the sample size of the original study. No effect of illness recency on attentional bias for disfigured faces emerged. Though it did not support the original finding, this replication provides suggestions for future research on the psychological underpinnings of pathogen avoidance.

Disgust regulation between menstrual cycle phases: Differential effects of emotional suppression and reappraisal

BACKGROUND AND OBJECTIVE

Immunosuppression is characteristic of the luteal phase of the menstrual cycle and is accompanied by an adaptive disgust response to reduce contact with pathogens. However, research has not examined the effects of emotion regulation on disgust during the menstrual cycle. Accordingly, the present study examines the effect of suppression and reappraisal on disgust during the luteal and follicular phases of the menstrual cycle.

METHOD

Menstrual cycle phase was estimated in a sample of naturally cycling women (n = 73), and those in the follicular or luteal phase were assigned to suppress or reappraise disgust while watching a disgust-inducing video. Physiological arousal during the video and avoidance of disgust cues in a public restroom after the video were also assessed.

RESULTS

No differences were observed in self-reported disgust to the video between those who suppressed and those who reappraised in the luteal phase. However, women in the follicular phase who suppressed reported less disgust than those who reappraised. The emotion regulation strategies did not influence physiology during the video or avoidance after the video as a function of menstrual cycle phase.

LIMITATIONS

Hormone assay data was not collected to confirm menstrual cycle phase and a relatively small sample of naturally cycling women was used.

CONCLUSIONS

Suppression may be a more effective strategy than reappraisal for reducing verbal disgust in the follicular phase but not in the luteal phase. The implications of these findings for the treatment of disgust-based disorders among women are discussed.

Alcohol and disgust: An intimate relationship

BACKGROUND

Alcohol intoxication has been associated with increases in risk taking behavior and more ambiguously, alterations in emotional perception. In the first study of its kind, we examine how theories of disgust can be used to help explain these effects.

METHODS

Using a single-blind procedure, participants (n = 73) were randomly allocated to an alcohol (Males: 0.68 g/kg; Females: 0.60 g/kg) or placebo condition and then completed a psychometric measure of disgust (TDDS).

RESULTS

Results revealed a non-significant trend toward lower disgust sensitivity in the alcohol versus placebo condition. We did however find a significant negative correlation, whereby increases in breath alcohol level were associated with decreased pathogen disgust.

CONCLUSIONS

These findings demonstrate a relationship between breath alcohol level and disgust sensitivity which could help explain differences in risk associated behavior.