The study, published in Frontiers in Psychiatry by a team at TSUMURA & CO., a Japanese Kampo pharmaceutical company, addresses a condition that touches the vast majority of women of reproductive age. More than 90 percent of women aged 20 to 49 experience some premenstrual symptoms, according to a meta-analysis cited by the authors. When at least five symptoms are present, including at least one psychological and one physical symptom, the condition is diagnosed as premenstrual dysphoric disorder (PMDD), a severe form that can impair daily life, work, and relationships, and has been linked to an increased risk of perinatal depression.

Current first-line treatments leave many patients underserved. Selective serotonin reuptake inhibitors are recommended for moderate-to-severe affective symptoms, and hormonal therapies such as combined oral contraceptives are used to flatten ovarian hormone fluctuations, while lifestyle changes and cognitive behavioral therapy help some patients. But these approaches do not work uniformly and can carry adverse effects, which is why the search for additional options continues. Herbal medicines have attracted attention as complementary therapies for gynecological disorders, and Kamishoyosan is frequently prescribed for PMS after oral contraceptive treatment, with clinical reports describing improvement in irritability and headaches.

To dissect the mechanism, the researchers turned to the progesterone withdrawal model. Female Wistar rats received high-dose progesterone injections once daily for six days, followed by a 24-hour drug-free period. This abrupt withdrawal mimics the sharp hormonal decline that occurs just before menstruation and reliably induces anxiety- and depression-like behaviors in rodents. Liquid chromatography-mass spectrometry confirmed the expected hormonal rollercoaster: plasma and hippocampal levels of progesterone and its metabolite allopregnanolone spiked on the final injection day and collapsed to control levels after withdrawal.

Allopregnanolone is central to the story. This neurosteroid is a potent allosteric modulator of GABA type A receptors, the brain’s principal inhibitory machinery, and it normally exerts calming, anxiolytic, and antidepressant effects by enhancing GABA signaling. The prevailing view holds that it is not the absolute level of allopregnanolone but its wild fluctuations and the resulting impaired GABA receptor responses that drive PMS pathogenesis. Notably, in this study, allopregnanolone levels after withdrawal did not differ between treated and control animals, pointing the finger at altered receptor function rather than hormone levels per se.

That altered function has a specific molecular signature. GABA type A receptors are chloride channels assembled from combinations of 19 possible subunits, and their composition dictates their behavior and pharmacology. Receptors containing the alpha4 and delta subunits sit mainly outside synapses and mediate tonic inhibition. During progesterone withdrawal, expression of these subunits rises in the hippocampus, amygdala, and periaqueductal gray matter, a change associated with reduced GABA currents, increased seizure susceptibility, and heightened anxiety. Using in situ hybridization, the team showed that withdrawal rats had significantly increased alpha4 and delta subunit mRNA in pyramidal cells of the hippocampal CA1 region, with the alpha4 signal also appearing in outer layers of the pyramidal cell layer, hinting that GABAergic interneurons may be involved as well.

Behaviorally, the effects were clear. In the elevated plus maze, a standard test in which rodents that spend more time exploring open, elevated arms are considered less anxious, withdrawal rats showed reduced open-arm time, a higher anxiety index, fewer open-arm entries, and more time in enclosed arms. Kamishoyosan, delivered through the diet at an estimated dose of roughly 2,000 milligrams per kilogram per day starting four days before progesterone administration, attenuated these alterations. Open-arm entries increased significantly with treatment, while enclosed-arm entry counts were unchanged across groups, indicating that locomotor activity was not a confound. Effect sizes were large across behavioral measures, though the authors note that observed power varied and that a single behavioral paradigm is a limitation.

Crucially, the herb’s benefit did not come from smoothing the hormonal storm. Pharmacokinetic analysis showed that plasma progesterone peaked 30 minutes after the final injection and fell by more than half within 240 minutes, with hippocampal concentrations tracking plasma closely and allopregnanolone showing similar dynamics. Kamishoyosan-treated animals displayed essentially the same hormone trajectories, with no significant differences in peak concentrations or drug exposure. Gene expression analysis of GABA-synthesizing enzymes, the vesicular GABA transporter, the GAT-1 reuptake transporter, and EGR3, a transcription factor that regulates the alpha4 subunit gene, likewise revealed no significant differences among groups after batch-effect adjustment. The authors conclude that Kamishoyosan appears to act through a direct, plastic change in the GABAergic system rather than by altering steroid hormone levels or GABA production and transport.

This mechanism distinguishes Kamishoyosan from conventional GABA-targeting drugs. Benzodiazepines such as diazepam enhance GABA signaling by binding to the receptor, but chronic use carries risks of dependence, tolerance, falls, and delirium, and chronic benzodiazepine administration itself increases alpha4 subunit expression, a change implicated in tolerance. Sensitivity to these drugs also decreases after progesterone withdrawal. Because Kamishoyosan suppressed the withdrawal-induced rise in alpha4 and delta subunits rather than binding to the receptor, the authors suggest it may work in a fundamentally different way, one that could even offer a route to reversing tolerance caused by benzodiazepine-like drugs, though they caution that the exact mechanisms and whether tolerance reversal truly occurs remain to be studied.

The formula itself is a blend of ten crude drugs, several with documented anxiolytic or hormone-related activities: geniposide from Gardeniae Fructus has shown anxiolytic effects in social interaction tests, paeonol from Paeoniae Radix eased anxiety-like behavior in PMS model rats, saikosaponin D from Bupleuri Radix exhibits estrogen-like and hypothalamic-pituitary-adrenal axis regulatory effects, and isoliquiritigenin from Glycyrrhizae Radix acts as a positive allosteric modulator of GABA type A receptors. Kamishoyosan is an approved pharmaceutical in Japan, and clinical studies, including a double-blind placebo-controlled trial in menopausal women, have reported favorable safety with no serious adverse events. An open-label randomized controlled trial evaluating its efficacy and safety for PMS is currently underway. The authors acknowledge limitations, including the single dose tested, reliance on one behavioral test, and the need for a priori power planning, but they position the findings as evidence that Kamishoyosan reverses reduced GABA receptor sensitivity and may inform future PMS treatments that sidestep the drawbacks of existing options.

Subject of Research: Anxiolytic mechanism of the Kampo medicine Kamishoyosan in a progesterone withdrawal rat model of premenstrual syndrome

Article Title: Kamishoyosan reduces anxiety-like behavior by modulating GABAA receptor subunit expression in a premenstrual syndrome rat model

Article References: Harada-Nitta, S., Ogura, K., Konno, K., Nahata, M., Fujitsuka, N., & Tokita, Y. (2026). Kamishoyosan reduces anxiety-like behavior by modulating GABAA receptor subunit expression in a premenstrual syndrome rat model. Frontiers in Psychiatry, 17, Article 1799904. https://doi.org/10.3389/fpsyt.2026.1799904

Image Credits: AI Generated

DOI: 10.3389/fpsyt.2026.1799904

Keywords: premenstrual syndrome, PMDD, Kamishoyosan, Kampo medicine, GABA A receptor, allopregnanolone, progesterone withdrawal, hippocampus, anxiety, neurosteroids, alpha4 subunit, rat model

The research team, led by Duygu Gulec Satir of Ege University’s Nursing Faculty, set out to fill a conspicuous gap in the literature. While cyberchondria has been studied in general populations and among people with chronic illnesses, little was known about how the hormonal fluctuations of the menstrual cycle interact with online health information-seeking behavior. Premenstrual syndrome affects a large proportion of women of reproductive age, and its symptoms overlap with a wide range of other conditions, from thyroid disorders to depression. That diagnostic ambiguity, the researchers reasoned, might make young women with PMS especially vulnerable to compulsive searching, as they attempt to self-diagnose symptoms that shift predictably with their cycle.

The study recruited 451 nursing students, a population chosen because young university women are both heavy internet users and at an age when PMS symptoms are common. Participants completed an online questionnaire that included the Premenstrual Syndrome Scale, which screens for and quantifies the severity of premenstrual symptoms, and the Cyberchondria Severity Scale, a validated 15-item instrument that measures the distress, compulsion, and reassurance-seeking dimensions of excessive online health searching. The researchers also collected data on daily internet use, perceived stress, economic income, and alcohol consumption, allowing them to statistically separate the effect of PMS from other factors known to influence both internet habits and health anxiety.

The findings paint a coherent picture of a digitally mediated feedback loop. Students whose scores suggested possible PMS reported greater online health information-seeking behaviors than their peers, and PMS scores correlated positively and significantly with cyberchondria severity scores. When the team ran a multiple linear regression controlling for income, alcohol use, perceived stress, and time spent online, PMS severity remained an independent predictor of cyberchondria. In other words, the association was not simply explained by the fact that anxious or stressed people spend more time on the internet; the premenstrual symptom burden itself appeared to drive the compulsive searching pattern.

Notably, the topics these young women searched for most frequently were menstrual irregularity, dysmenorrhea, and premenstrual symptoms themselves. This is a telling detail. Rather than browsing randomly about exotic diseases, the students were searching for information directly related to their own lived experience, seeking explanations for bodily changes they could feel but not fully understand. The internet, in this sense, functions as an accessible first-line consultant, available at any hour and free of charge. Yet the quality and framing of what they encounter online can vary enormously, and for someone whose symptoms fluctuate with her hormonal cycle, contradictory or alarming search results may amplify uncertainty rather than resolve it.

The study also found that daily internet use was positively associated with both PMS and cyberchondria scores, although the researchers were careful to note that these associations were small in magnitude. That caveat matters. The data do not suggest that spending hours online causes PMS, or that PMS inevitably produces cyberchondria. Instead, the relationships are statistical tendencies observed in a single snapshot of time. Because the design was cross-sectional, measuring exposure and outcome simultaneously, it cannot establish which comes first. It is plausible that women troubled by premenstrual symptoms search more, that compulsive searchers become more attuned to and distressed by bodily sensations, or that both dynamics reinforce each other in a cycle that future longitudinal studies will need to disentangle.

Cyberchondria itself is a concept that has gained increasing attention as smartphones have made health information permanently accessible. Psychologists describe it as a maladaptive form of health anxiety in which repeated online searches provide only fleeting reassurance, followed by renewed worry, often triggered by encountering serious conditions that share superficial features with benign symptoms. The Cyberchondria Severity Scale used in this study captures this compulsion, distress, and excessiveness, and its 15-item short form has become a standard tool in the field. The Turkish research team’s application of it to a menstrual health context is one of the first attempts to connect cyclical hormonal symptomatology with this digital-era anxiety pattern.

The choice of nursing students as the study population adds an interesting layer of interpretation. These are young women with formal health education, presumably better equipped than the average internet user to evaluate medical sources critically. If even a health-literate population shows elevated cyberchondria in association with PMS, the authors’ concern about the broader population of young women may be warranted. At the same time, the sample’s homogeneity, limited to nursing students at Turkish universities, means the findings cannot be generalized to all young women, men, or older age groups without further research. The authors themselves frame the work as descriptive and correlational, an early mapping of a territory rather than a definitive causal account.

What the study does establish is a practical signal for healthcare professionals. The authors conclude that clinicians should guide young women with PMS toward reliable online health resources and support the development of digital health literacy skills. This recommendation reflects a pragmatic view of the internet’s role in health behavior: rather than telling patients to stop searching, which rarely works, providers can redirect that energy toward vetted sources and teach the skills needed to interpret what they find. For menstrual health specifically, this could mean pointing patients to evidence-based resources that explain the normal range of premenstrual experiences, the red flags that genuinely warrant medical evaluation, and the ways hormonal cycles can legitimately produce a wide spectrum of physical and emotional symptoms.

The research also arrives at a moment of broader cultural conversation about how digital platforms shape health behavior, from TikTok trends that popularize self-diagnosed conditions to algorithmic feeds that can funnel users toward increasingly alarming content. This study does not examine social media algorithms, but it contributes an important piece of evidence: a physiological, cyclical condition like PMS is associated with measurable increases in problematic health-related internet use. As the authors and the journal’s indexed subject areas suggest, the intersection of gynecology, cyberpsychology, and mental health is likely to attract growing research attention. For now, the message for young women navigating premenstrual symptoms is nuanced: the impulse to search is understandable and common, but the searching itself may carry a psychological cost, and a conversation with a healthcare provider, paired with trustworthy online sources, remains the more reliable path to reassurance.

Subject of Research: The relationship between premenstrual syndrome, internet use behaviors, and cyberchondria in young women

Article Title: Cyberchondria levels and internet use behaviors of young women with premenstrual syndrome: a cross-sectional study

Article References: Gulec Satir, D., Kavlak, O., Tetik, S., & Başak, H. (2026). Cyberchondria levels and internet use behaviors of young women with premenstrual syndrome: a cross-sectional study. BMC Psychology. https://doi.org/10.1186/s40359-026-05729-2

Image Credits: AI Generated

DOI: 10.1186/s40359-026-05729-2

Keywords: premenstrual syndrome, cyberchondria, internet use, health anxiety, digital health literacy, online health information-seeking, young women, menstrual health, cross-sectional study, nursing students, cyberpsychology, mental health