by Karolina Milkowska
In periods when the body’s immunity is lowered or the risk of infection rises, people should show increased prophylactic behavior. It is assumed that the feeling of disgust is a mechanism that should protect against contact with the source of infection. The increased susceptibility of the organism to infections can be compensated by recognizing the potential threat and by avoiding or eliminating the identified threats thanks to preventive actions.
In women, the functioning of the immune system may be influenced by progesterone levels, a sex hormone that is produced in the luteal phase of the menstrual cycle, following the rupture of the Graaf follicle (ovulation). Progesterone causes immunosuppressive stimulation of the immune system, by reducing inflammatory immune responses. Such modification of the immune response i) prevents the female immune system from attacking the genetically half-foreign blastocyst, ii) enables implantation and development of the embryo, iii) but also makes women more susceptible to infections.
According to the Compensatory Prophylaxis Hypothesis (CPH), women in the luteal phase of the menstrual cycle should show stronger disgust and more increased prophylactic behavior than during the follicular phase, in order to avoid infections in periods of reduced immunity by avoiding potential sources of infection.
In a recent study, we explored whether disgust sensitivity differs between phases of the menstrual cycle in regularly cycling, healthy women of reproductive age, who performed ovulatory tests to determine the phases of the menstrual cycle and repeatedly assessed the disgust level using both questionnaires and photographs of potential sources of infections.
Disgust sensitivity was measured twice during one menstrual cycle among all participants:
1) 5th or 6th day of the cycle
2) and on the 5th day after a positive LH test, or on the 20th day of a cycle if the result of LH test was not positive (indicating that the cycle was anovulatory).
Disgust was assessed by the Pathogen and Moral domains of the Three-Domain Disgust Scale (TDDS) and a set of photographs depicting potential sources of infection. Moreover, we measured contamination sensitivity with the use of Contamination Obsessions and Washing Compulsions Subscale of Padua Inventory – Washington State University Revision.
During the luteal phase, compared to the follicular phase, women scored higher on the:
1) Pathogen Disgust of Three-Domain Disgust Scale,
2) Contamination Obsessions and Washing Compulsions Subscale of Padua Inventory,
3) and when rating their disgust level while watching photographs depicting sources of a potential infection.
Did other studies get the same results?
Our results are consistent with several previous findings. Among studies that measured progesterone levels when testing CPH, Fleischman and Fessler (2011) and Żelaźniewicz et al. (2016) have shown a positive correlation between progesterone and the feeling of disgust toward pathogenic factors. However, a recent study with a large study sample has shown a lack of association between progesterone and the pathogen disgust sensitivity. Studies comparing pathogen disgust sensitivity within the phases of the menstrual cycle also provided inconclusive findings. For example, a previous study has shown, contrary to our results, a lack of significant differences in the Pathogen Disgust domain of the TDDS. One other study found that only women who had an ongoing infection had higher scores on the Pathogen Disgust domain of the TDDS while being in the luteal phase than women in the follicular phase. Further, a study by Fessler and Navarrete (2003), contrary to our research, revealed no differences in the intensity of the feeling of disgust across the cycle – women in the luteal phase did not differ from women in the follicular phase. However, they did not conduct ovulatory tests or repeated measurements of disgust.
Similar to some of the previous research no statistically significant differences in the Moral Disgust domain of TDDS were observed across the menstrual cycle. This is consistent with predictions of the CPH that postulates changes in avoiding pathogens and sources of infections, as opposed to changes in disgust with socio-moral violations, such as theft.
We believe that understanding how the feeling of disgust varies in relation to phases of the menstrual cycle or to progesterone status could be useful in designing effective disease prevention strategies for women.
What are the practical implications of the obtained results?
The feeling of disgust can be used as a mechanism in strategies aiming to improve health, e.g., within public health programs in response to pandemics such as COVID-19. Moreover, as disgust is a basic symptom of many psychopathologies, it has important implications for psychological welfare. Hence, we believe that understanding how the feeling of disgust varies in relation to phases of the menstrual cycle or to progesterone status (e.g., in women using hormonal contraceptives, or in postmenopausal women) could be useful in designing effective disease prevention strategies for women. If indeed women are more sensitive to disgusting stimuli during the luteal phase, perhaps public health interventions focused on infections could be more effective during this time of a cycle. Additionally, public health interventions could also be focused on rising women’s awareness that their disgust levels might be narrowed in the follicular phase of the cycle resulting in potential disease as well. Also, post-menopausal women have very low progesterone levels, thus if progesterone is involved in disgust perception, it could be hypothesized that at an older age women need stronger stimuli to elicit this behavior.
In conclusion, our study provides support for the CPH, showing increased pathogen disgust sensitivity and contamination sensitivity in the luteal phase among healthy women of reproductive age. To the best of our knowledge, we present the first study that used ovulatory tests, repeated measurements of disgust, and both questionnaires and photographs of potential sources of infections to test the CPH. We suggest that future studies testing the CPH should adopt these methods.
Read the paper: Pathogen disgust, but not moral disgust, changes across the menstrual cycle