Gender differences in chronic pruritus: women present different morbidity, more scratch lesions and higher burden

Unmet needs in treating itch: reaching beyond eczema

PURPOSE

Pruritus is an unpleasant sensation that creates the urge to scratch. In many chronic conditions, relentless pruritus and scratching perpetuates a vicious itch-scratch cycle. Uncontrolled itch can detrimentally affect quality of life and may lead to sleep disturbance, impaired concentration, financial burden, and psychological suffering. Recent strides have been made to develop guidelines and investigate new therapies to treat some of the most common severely pruritic conditions, however, a large group of diseases remains underrecognized and undertreated. The purpose of this article is to provide a comprehensive review of the challenges hindering the treatment of pruritus.

METHODS

An online search was performed using PubMed, Web of Science, Google Scholar, and ClinicalTrials.gov from 1994 to 2024. Included studies were summarized and assessed for quality and relevance in treating pruritus.

RESULTS

Several barriers to treating pruritus emerged, including variable presentation, objective measurement of itch, and identifying therapeutic targets. Itch associated with autoimmune conditions, connective tissue diseases, genodermatoses, cutaneous T-cell lymphoma, and pruritus of unknown origin were among the etiologies with the greatest unmet needs.

CONCLUSION

Treating pruritus poses many challenges and there are many itchy conditions that have no yet been addressed. There is an urgent need for large-scale controlled studies to investigate potential targets for these conditions and novel therapies.

The G protein-coupled estrogen receptor of the trigeminal ganglion regulates acute and chronic itch in mice

AIMS

Itch is an unpleasant sensation that severely impacts the patient's quality of life. Recent studies revealed that the G protein-coupled estrogen receptor (GPER) may play a crucial role in the regulation of pain and itch perception. However, the contribution of the GPER in primary sensory neurons to the regulation of itch perception remains elusive. This study aimed to investigate whether and how the GPER participates in the regulation of itch perception in the trigeminal ganglion (TG).

METHODS AND RESULTS

Immunofluorescence staining results showed that GPER-positive (GPER+ ) neurons of the TG were activated in both acute and chronic itch. Behavioral data indicated that the chemogenetic activation of GPER+ neurons of the TG of Gper-Cre mice abrogated scratching behaviors evoked by acute and chronic itch. Conversely, the chemogenetic inhibition of GPER+ neurons resulted in increased itch responses. Furthermore, the GPER expression and function were both upregulated in the TG of the dry skin-induced chronic itch mouse model. Pharmacological inhibition of GPER (or Gper deficiency) markedly increased acute and chronic itch-related scratching behaviors in mouse. Calcium imaging assays further revealed that Gper deficiency in TG neurons led to a marked increase in the calcium responses evoked by agonists of the transient receptor potential ankyrin A1 (TRPA1) and transient receptor potential vanilloid V1 (TRPV1).

CONCLUSION

Our findings demonstrated that the GPER of TG neurons is involved in the regulation of acute and chronic itch perception, by modulating the function of TRPA1 and TRPV1. This study provides new insights into peripheral itch sensory signal processing mechanisms and offers new targets for future clinical antipruritic therapy.

The impact of phototherapy on itch intensity and itch-related quality of life amongst different skin diseases, skin phototypes and genders - A prospective study with 102 patients

BACKGROUND

Phototherapy is a mainstay to treat itchy conditions. However, only little is known about differences in the antipruritic effect of phototherapy amongst different skin conditions, phototypes and genders.

METHODS

In this prospective, single-center study, we analyzed the effect of phototherapy on itch intensity and itch-related quality of life amongst these subgroups after a treatment duration of 4 weeks, while on-demand treatment with topical corticosteroids, topical calcineurin inhibitors and/or antihistamines was allowed.

RESULTS

Of 102 patients (age 53.0 ± 18.7, 56 females [54.9%]), 72 (78.3%) reported a significant reduction of itch intensity by Δ -2.76 on a 0-10 Numerical Rating Scale (NRS), p = <.001, 95% CI [2.2; 3.3] paralleled by a significant improvement of itch-related quality of life as measured by the German version of the ItchyQoL by Δ 7.3, p = <.001, 95% CI [4.4; 11.6]. The best improvement of itch intensity and itch-related QoL was reported by patients with pruritus on non-diseased skin (ΔNRS -3.5; Δ 9.7 Ger-ItchyQoL points), followed by patients with atopic dermatitis and psoriasis. We found no statistical differences in the response to phototherapy amongst Fitzpatrick phototypes I-VI. Women had higher itch intensities at baseline but itch-related quality of life impairment at baseline and phototherapy treatment response did not significantly differ between genders.

CONCLUSION

Phototherapy appears to induce a meaningful itch reduction in various itchy skin conditions, all phototypes and both genders within 4 weeks that directly translates into improvement of itch-related quality of life.

Prevalence and Characteristics of Itch and Pain in Patients Suffering from Chronic Hand Eczema

BACKGROUND

Hand eczema (HE) is a frequent chronic inflammatory dermatosis. Itch and pain are considered two of the most common and burdensome symptoms of the disease. Yet, the data related to these symptoms are still limited. The aim of this study was to evaluate characteristics of itch and pain in adults suffering from HE.

METHODS

The study group comprised 100 adult HE patients. An original questionnaire designed by the authors was used to survey the patients. It included questions regarding demographic characteristics such as the duration of the disease, exacerbation count, past diagnostics and treatment, as well as atopic predispositions. Additionally, the itch and pain intensity (numerical rating scale-NRS) during '3 days prior to the study' and the 'entire disease' period was implemented. The clinical assessment of the disease severity was performed according to two specific measurement instruments: Investigator Global Assessment for Chronic Hand Eczema (IGA-CHE) scale and Hand Eczema Severity Index (HECSI). To assess patient quality of life (QoL), the DLQI tool was used and to determine the level of stigmatization and for its impact on patients' life the 6-Item Stigmatization Scale (6-ISS) was employed.

RESULTS

Within the period of 3 days prior to the examination, itch was reported by 81.0% of patients (n = 81), whereas 53.0% (n = 53) of them experienced pain. Both symptoms were reported more frequently in females (itch: p = 0.022; pain: p = 0.033). When sexes were compared, females reached higher scores in both IGA-CHE and HECSI. Itch and pain intensity correlated positively with disease severity. The intensity of itch and pain significantly influences HE patients' QoL. A positive correlation between the 6-ISS score and the intensity of itch in the 'last 3 days' period was revealed (r = 0.221; p = 0.027).

CONCLUSIONS

Itch and pain are common symptoms in HE patients, significantly contributing to the feeling of stigmatization. Providing characteristics of itch and pain may improve HE management. Symptom-decreasing treatment would definitely have a positive influence on patients' well-being.

Predictive factors of quality of life in chronic pruritus patients: A cross-sectional study

Background

Chronic pruritus severely impacts the quality of life (QoL) of patients. Due to its multifactorial nature, the presence of factors that can predict itch-specific QoL needs comprehensive exploration.

Objective

To determine the sociodemographic and itch-related factors that predict itch-specific QoL among patients suffering from chronic pruritus.

Methods

We conducted a cross-sectional study on a cohort of patients with chronic pruritus at our itch clinic in Miami, Florida from 2016 to 2022 and explored predictors of itch-specific QoL using simple and multivariable linear regression models.

Results

Sociodemographic factors that had a negative impact on itch-specific QoL included female sex and multiracial ethnicity. The main itch-related factors that were associated with a negative impact on itch-specific QoL included pruritus in the upper extremity and buttocks/genital regions and associated factors such as pain, cold sensation, sweating, and stress.

Limitations

Single-center study at a tertiary care center with a primarily non-Hispanic White population and use of self-administered questionnaires.

Conclusions

A variety of factors help predict the itch-specific QoL in patients with chronic pruritus. Understanding these factors can help clinicians evaluate and treat patients suffering from chronic itch.

Odevixibat: A Review of a Bioactive Compound for the Treatment of Pruritus Approved by the FDA

Odevixibat is synthesized through chemical modification of Benzothiazepine's structure. It is a tiny chemical that inhibits the ileal bile acid transporter and is used to treat a variety of cholestatic illnesses, including progressive familial intrahepatic cholestasis (PFIC). For cholestatic pruritus and liver disease development, bile acid transporter inhibition is a unique treatment strategy. Odevixibat reduces enteric bile acid reuptake. Oral odevixibat was also studied in children with cholestatic liver disease. Odevixibat received its first approval in the European Union (EU) in July 2021 for the treatment of PFIC in patients aged 6 months, followed by approval in the USA in August 2021 for the treatment of pruritus in PFIC patients aged 3 months. Bile acids in the distal ileum can be reabsorbed by the ileal sodium/bile acid cotransporter, a transport glycoprotein. Odevixibat is a sodium/bile acid co-transporter reversible inhibitor. An average 3 mg once-daily dose of odevixibat for a week resulted in a 56% reduction in the area under the curve of bile acid. A daily dose of 1.5 mg resulted in a 43% decrease in the area under the curve for bile acid. Odevixibat is also being evaluated in many countries for the treatment of other cholestatic illnesses, including Alagille syndrome and biliary atresia. This article reviews the updated information on odevixibat with respect to its clinical pharmacology, mechanism of action, pharmacokinetics, pharmacodynamics, metabolism, drug-drug interactions, pre-clinical studies, and clinical trials.

[From ocular itching to eye rubbing: a review of the literature]

Ocular itching and eye rubbing are frequent complaints in an ophthalmology practice. Numerous studies address the consequences of eye rubbing, such as keratoconus. However, there are few studies concerning the pathophysiology of itching, its transmission pathways, or its interactions with eye rubbing. Through this literature review, we will address the various clinical, physiological and therapeutic aspects of this pair of symptoms with a variety of ocular consequences. We will then describe the state of the art in itching and scratching in dermatology, in order to draw a parallel between these two vicious cycles. A better understanding of the pathophysiology of ocular itching and eye rubbing, as well as new studies based on dermatological data, might allow more appropriate clinical management of our patients and their symptoms.

Association between Pruritus and Psychosocial Well-being: A Population-based Study among 6,809 Subjects

Pruritus has an extensive impact on functional, social and psychosocial behaviour. The association between pruritus and psychological well-being has mostly been studied among selected patient groups, whereas population-based studies are lacking. The aim of this study was to determine the association between pruritus and insomnia, quality of life, depression and anxiety at the population level in the general population. A cross-sectional population-based study was conducted in 2012 to 2013. Study subjects (n = 6,809) belonging to the Northern Finland Birth Cohort 1966 Study participated in a large follow-up study at the age of 45-47 years. They completed an extensive health questionnaire including questions on pruritus and several previously validated questionnaires regarding symptoms of psychosocial well-being. Pruritus affected 19.9% of the study subjects weekly, being more common in women than in men (p < 0.001). A significant association was found between both localized and generalized pruritus and symptoms of insomnia, depression, anxiety and decreased quality of life. The association was seen even in those with mild psychological symptoms/insomnia, and it affected both sexes. The severity of psychological symptoms increased with increasing frequency of pruritus. In conclusion, pruritus has a multiple effect on psychosocial well-being. Physicians should consider possible psychosocial symptoms in patients with pruritus.

The use of SCL-k-9 to measure general psychopathology in women and men with skin conditions

Objectives

To measure general psychopathology in dermatologic outpatients using the Symptom-Checklist-K-9 (SCL-K-9); to investigate whether the SCL-K-9 is able to categorize patients with and without significant non-psychotic disorders; and to perform a single-item analysis of the SCL-K-9, with a focus on gender differences.

Methods

Cross-sectional study on consecutive dermatological patients. We used two self-administered questionnaires to assess general psychopathology symptoms: General Health Questionnaire-12 (GHQ-12) and SCL-K-9. Sociodemographic information was collected with standardized forms. The performance of the SCL-K-9 in classifying patients according to their current emotional distress severity was assessed using a ROC procedure. Finally, we measured differences in scores obtained among women and men in SCL-K-9 single items.

Results

A total of 292 patients were studied (71.2% women). We observed statistically significant differences in SCL-K-9 total mean scores and in most single items among genders. We found that it would be more appropriate to use gender-specific cut-offs when using SCL-K-9 to screen dermatological patients for general psychopathology.

Conclusion

The SCL-K-9, with its compact format could provide, in a short time, a wide range of information related to critical areas that challenge the mental health of patients with skin diseases.

[Relevance of demographic and psychological factors in pruritus]

BACKGROUND

Pruritus is a frequent phenomenon in patients in dermatology. The severity of pruritus often cannot be explained by the severity of the underlying disease or chronification processes alone. Especially then, demographic and psychological variables should also be considered as moderators of the intensity of pruritus.

PURPOSE

Are there associations between sex, age, emotional and cognitive factors and pruritus intensity in patients with chronic pruritus (CP) and skin-healthy control subjects?

MATERIAL AND METHODS

Recently published studies on the abovenamed moderators of pruritus were searched for in PubMed, collated and the results are summarized.

RESULTS

It was found that women reported a higher intensity of pruritus than men. In addition, negative emotions such as fear, disgust, and anger are positively associated with pruritus in patients with CP. There are also associations between cognitive factors, such as attention, catastrophizing, and pruritus.

CONCLUSION

The associations between both demographic and psychological factors and pruritus should be considered in the diagnostics and treatment of pruritus. A psychological intervention as a complementary treatment should be considered whenever patients report associations between psychological experiences and pruritus and/or automatic or extensive scratching.

Prevalence and potential risk factors of chronic pruritus among community middle-aged and older population in Beijing, China

BACKGROUND

Chronic pruritus is a common problem among older adults, with a significant impact on their quality of life. However, it is under-studied epidemiologically, especially among Chinese older adults.

OBJECTIVE

To identify the prevalence and explore the risk factors of chronic pruritus among the middle-aged and older adults in Beijing, China.

METHODS

A total of 929 participants aged ≥35 years from six communities in Beijing, China, were interviewed. The survey collected the demographic characteristics, the experience of chronic pruritus (>6 weeks), chronic disease history, the level of physical activities, and sleep quality. A population-based case-control study was conducted, including 178 chronic pruritus cases and 697 controls. A multivariate logistic regression model was performed to explore the risk factors of chronic pruritus. Additionally, a random forest algorithm was used to rank the importance of potential risk factors and analyze the overall interpretation of risk factors.

RESULTS

The prevalence of chronic pruritus was 19.48% (181/929) among the Beijing middle-aged and elderly population. The findings indicated that older adults aged 65 years old or above, male, with college or higher degree, alcohol drinking, hypertension, hyperlipidemia, chronic lung disease, cardiovascular disease, digestive system disease and osteoarthritis/rheumatism, middle or low sleep quality were associated with the increased risk of chronic pruritus, respectively. Physical activity level (≥3000 Met) was associated with a decreased risk of chronic pruritus. The rank according to the most contribution of chronic pruritus risk was sleep quality, education, physical activity level, osteoarthritis/rheumatism, age, and gender.

CONCLUSION

Prevalence of chronic pruritus was high among the Chinese middle-aged and elderly population. Age, gender, high education, alcohol drinking, hypertension, hyperlipidemia, chronic lung disease, cardiovascular disease, digestive system disease, osteoarthritis /rheumatism, poor sleep quality may serve as risk factors of chronic pruritus. Moderate and high physical activity levels may serve as protective factors of chronic pruritus risk.

Optimizing doxepin therapy in dermatology: introducing blood level monitoring and genotype testing

Doxepin, a tricyclic antidepressant, is the most efficacious antipruritic available to dermatologists; however its use is often suboptimal because of significant interindividual variability in doxepin plasma levels and clinical response between patients taking the same dose. As result, the Food and Drug Administration approves a maximum dose of 300 mg of doxepin per day and a 10 mg per cc liquid doxepin concentrate. These allow patients to significantly increase or decrease their dose, due to either a lack of clinical efficacy or side effects at typical dermatologic doses (often 10-25 mg per day). This review initially discusses the unique advantages of doxepin in dermatology. Then, it explores internal and external reasons why doxepin plasma levels and clinical response vary so significantly between patients, including genetic polymorphisms, drug interactions, comorbidities, sex, and ethnicity. Blood level monitoring is introduced, a tool dermatologists can use to optimize doxepin dosing in patients responding subtherapeutically to typical dermatologic doses. Without blood level monitoring, patients initially unresponsive to treatment could be labeled treatment failures when in fact they may be cases of inadequate dosing. Blood level monitoring allows for safe dose adjustments in these individuals to maximize patients' chances of achieving therapeutic success with this agent.

Itch: Epidemiology, clinical presentation, and diagnostic workup

Itch, or pruritus, is the uncomfortable sensation underlying the desire to scratch. Itch is a very common complaint in the general population that can result from dermatologic, systemic (eg, renal, hepatobiliary, endocrine), paraneoplastic, neuropathic, and psychogenic etiologies. Chronic itch is associated with significant sleep disturbances and profoundly reduces overall quality of life. Certain populations, including elderly and African Americans, are at increased risk of experiencing heightened burden of itch. Because of the variable clinical presentation and wide-ranging etiologies, itch presents a challenge for clinicians. The initial evaluation should include a complete blood count, with differential, hepatic, renal, and thyroid function testing along with diabetes screening. Further testing should be guided by history and physical examination findings. There should be a heightened concern for underlying malignancy in individuals older than 60 years of age who have a history of liver disease and diffuse itch less than 12 months of duration. For individuals with chronic pruritus of unknown origin, increased blood eosinophils may serve as a biomarker of T helper cell type 2 polarization and response to immunomodulator therapies. In this first part of a 2-part continuing medical education series, we describe the broader epidemiology and specific conditions associated with itch and the clinical presentation and diagnostic workup for patients with itch.

Identifying Epidermolysis Bullosa Patient Needs and Perceived Treatment Benefits: An Explorative Study Using the Patient Benefit Index

Epidermolysis bullosa (EB) is a genetic blistering skin condition for which no cure exists. Symptom alleviation and quality of life are therefore central to EB care. This study aimed to gain insight into EB patient needs and benefits from current clinical care. Two questionnaires were administered cross-sectionally to adult EB patients at the Dutch expertise centre for blistering diseases. Patient needs and benefits were analyzed using the patient benefit index survey (PBI-S). Ancillary data were compiled pertaining to self-reported EB severity, pain and pruritus, as well as current and previous treatments. In total, 104 participants were included (response rate 69.8%). Sixty-eight participants comprised the analyzed cohort (n = 36 omitted from analysis). The needs given the highest importance were to get better skin quickly (64.7%) and to be healed of all skin alterations (61.8%). A positive correlation between pain and EB severity and the importance of most needs was observed. Minimal clinically important differences within the PBI-S, relating to reported benefits from clinical care, were reported by 60.3% of the cohort. This study highlights a discrepancy between patient needs and feasible treatment outcomes. Utilizing the PBI-S in conjunction with well-established multidisciplinary care may catalyze the process of tailoring treatments to the needs of individual patients.

Interleukin-31 Serum And Pruritus Dimension After Acupuncture Treatment In Hemodialysis Patients: A Randomized Clinical Trial

BACKGROUND: Interleukin (IL)-31 serum levels were significantly higher in hemodialysis patients with pruritus, whereas acupuncture in LI11 was shown to improve symptoms of pruritus. However, there is limited information that IL-31 serum levels that correlate with decreased dimensions of the pruritus after acupuncture in LI11 in a hemodialysis patient. AIM: The aim of the study was to demonstrate the impact of acupuncture in LI11 and IL-31 serum level and its correlation with dimensions of the pruritus in hemodialysis patients. METHODS: A randomized clinical trial has been carried out from August 2019 to December 2019 at H. Adam Malik General Hospital, Medan, Indonesia. Sixty patients underwent hemodialysis who were randomly allocated to two groups, one group got acupuncture in Quchi LI11 (intervention group), and the other group got a placebo (control group). IL-31 serum levels and pruritus were measured before and after 6 weeks of acupuncture in both groups. RESULTS: Acupuncture did not significantly reduce IL-31 (p = 0.931) and decreased dimensions: Degree, duration, disability, and distribution of the pruritus between the intervention group and the control group after 6 weeks of acupuncture in LI11. It can be shown that there is no significant correlation between IL-31 serum levels and dimensions of the pruritus. CONCLUSION: This study demonstrates the effect of acupuncture on reducing dimensions of the pruritus not related to IL-31 serum levels. Identifying the action mechanism of acupuncture to minimize pruritus considerably enhances knowledge of the impacts of acupuncture on reducing pruritus in hemodialysis patients.

Association between chronic pruritus, depression, and insomnia: A cross-sectional study

Background

Skin diseases that cause chronic pruritus can have negative effects on a patient's quality of life.

Objective

We evaluated the associations between chronic pruritus and psychological conditions including insomnia and depression.

Methods

This study included responses from 91 participants with chronic pruritus (response rate: 74.6%). A survey including questionnaires regarding data on demographic characteristics, intensity of pruritus using the visual analog scale (VAS) and the 4-item itch questionnaire, and the degrees of insomnia and depression measured by the Insomnia Severity Index and Beck Depression Inventory, respectively.

Results

Patients with symptoms of insomnia or depression had significantly more intense pruritus than patients without psychological symptoms (insomnia, VAS median [interquartile range]: 7.0 [5.0-8.25] vs. 5.0 [3.0-7.5]; depression, VAS median [interquartile range]: 7.5 [5.0-8.25] vs. 5.0 [3.0-7.0]). Multivariable analyses revealed that patients with moderate to severe pruritus were more likely to have depression than those with mild pruritus (odds ratio: 10.95; 95% confidence interval: 2.24-53.06). There were no differences in the severity of insomnia and depression among skin diseases.

Limitations

This study had a cross-sectional design and limited generalizability.

Conclusion

Chronic pruritus is significantly associated with insomnia and depression, regardless of the etiology.

Increased Prevalence of Face Mask-Induced Itch in Health Care Workers

BACKGROUND

Face mask use has increased significantly due to the COVID-19 pandemic. Health care workers (HCW) wear masks for prolonged periods and are prone to adverse effects. Very little is known about face-mask-associated itch.

METHODS

This Internet survey study investigated the prevalence, intensity and clinical characteristics of itch related to the use of face masks by HCW during the COVID-19 pandemic. The results were subsequently compared to the students' group.

RESULTS

A total of 1156 HCW completed the survey. Among them, 31.6% (365) reported suffering from itch associated with face mask use. Itch was more frequent among females. Moreover, subjects who reported sensitive skin, atopic predispositions and facial dermatoses tended to report itch more frequently. The worst case of itch in the seven days prior to the study, assessed with the numeric rating scale (NRS), was 4.6 ± 2.0 points. Itch prevalence increased along with the duration of face mask use, being 34.6% among those who wore masks for more than 4 h. HCW reported itch significantly more frequently than students.

CONCLUSIONS

Face-mask-associated itch is a frequent problem among HCW in the COVID-19 pandemic. Itch sensation may cause scratching, which may decrease necessary protection during the pandemic.

The impact of prurigo nodularis on quality of life: a systematic review and meta-analysis

Prurigo nodularis (PN) is a chronic, pruritic, debilitating disease. Previous studies found that chronic pruritus in general negatively affects patients' quality of life (QoL). However, results about the impact of PN on QoL are conflicting. Our objective was to assess the QoL burden of PN. A systematic review was conducted of all published studies that assessed QoL measures in PN. OVID MEDLINE, EMBASE, SCOPUS, and Web of Science were searched. Pooled meta-analysis (means) was performed using random-effects weighting. Overall, 13 studies met inclusion criteria. All studies identified QoL reductions in patients suffering from PN compared to control groups. The most common QoL instrument used was the Dermatology Life Quality Index [n = 9 studies; pooled mean (95% confidence interval): 13.8 (10.6-16.9), denoting a very large effect]. In particular, PN was associated with substantial impact on multiple domains of QoL. No publication bias was detected. In conclusion, QoL is negatively impacted in PN. Future studies are necessary to determine the best instruments of measuring QoL in PN patients, better understand this association, and assess the impact in males and females separately. PROSPERO CRD42019136193.

The characteristics and impact of pruritus in adult dermatology patients: A prospective, cross-sectional study

BACKGROUND

Pruritus often accompanies chronic skin diseases, exerting considerable burden on many areas of patient functioning; this burden and the features of pruritus remain insufficiently characterized.

OBJECTIVE

To investigate characteristics, including localization patterns, and burden of pruritus in patients with chronic dermatoses.

METHODS

We recruited 800 patients with active chronic skin diseases. We assessed pruritus intensity, localization, and further characteristics. We used validated questionnaires to assess quality of life, work productivity and activity impairment, anxiety, depression, and sleep quality.

RESULTS

Nine out of every 10 patients had experienced pruritus throughout their disease and 73% in the last 7 days. Pruritus often affected the entire body and was not restricted to skin lesions. Patients with moderate to severe pruritus reported significantly more impairment to their sleep quality and work productivity, and they were more depressed and anxious than control individuals and patients with mild or no pruritus. Suicidal ideations were highly prevalent in patients with chronic pruritus (18.5%) and atopic dermatitis (11.8%).

CONCLUSIONS

Pruritus prevalence and intensity are very high across all dermatoses studied; intensity is linked to impairment in many areas of daily functioning. Effective treatment strategies are urgently required to treat pruritus and the underlying skin disease.

Diagnostik von psychischen Faktoren bei chronischem Pruritus

Hintergrund

Pruritus ist ein häufiges und quälendes Symptom in der Bevölkerung sowie in ärztlichen Praxen.

Ziel der Arbeit

Der vorliegende Beitrag gibt einen Überblick über die Systematik psychischer Faktoren in Entstehung bzw. Verlauf des Pruritus sowie Hinweise zu ihrer jeweiligen Diagnostik

Material und Methode

Es handelt sich um eine Überblicksarbeit.

Ergebnisse

Psychische Beeinträchtigungen/Störungen können als Reaktion auf chronischen Pruritus auftreten, z. B. als Anpassungsstörungen, depressive Störungen, Angststörungen. Psychische Faktoren können auch in Entstehung und Verlauf eines chronischen Pruritus eine Rolle spielen, entweder im Zusammenspiel mit organischen Ursachen oder bei deren Fehlen als somatoformer Pruritus oder Pruritus bei coenästhetischer Schizophrenie. Ferner können selbstinduzierte Kratzartefakte mit oder ohne Pruritus im Rahmen von Störungen der Impulskontrolle, Zwangsstörungen oder Artefaktstörungen auftreten. Auch eine primär unabhängige Komorbidität mit einer sonstigen psychischen oder psychosomatischen Störung kann das Management des Pruritus erschweren und den Krankheitsverlauf beeinflussen. Es werden Hinweise zur Diagnostik der genannten Faktoren gegeben.

Diskussion

Die Diagnostik psychischer Einflussfaktoren und psychischer Aspekte des chronischen Pruritus ist komplex. Das wichtigste diagnostische Werkzeug ist die gründliche Anamneseerhebung auch bezüglich psychischer Aspekte. Zusätzlich können psychometrische Instrumente zum Einsatz kommen, die das ärztliche Gespräch jedoch nicht ersetzen.

Spinal cord NLRP1 inflammasome contributes to dry skin induced chronic itch in mice

BACKGROUND

Dry skin itch is one of the most common skin diseases and elderly people are believed to be particularly prone to it. The inflammasome has been suggested to play an important role in chronic inflammatory disorders including inflammatory skin diseases such as psoriasis. However, little is known about the role of NLRP1 inflammasome in dry skin-induced chronic itch.

METHODS

Dry skin-induced chronic itch model was established by acetone-ether-water (AEW) treatment. Spontaneous scratching behavior was recorded by video monitoring. The expression of nucleotide oligomerization domain (NOD)-like receptor protein 1 (NLRP1) inflammasome complexes, transient receptor potential vanilloid type 1 (TRPV1), and the level of inflammatory cytokines were determined by western blot, quantitative real-time PCR, and enzyme-linked immunosorbent assay (ELISA) kits. Nlrp1a knockdown was performed by an adeno-associated virus (AAV) vector containing Nlrp1a-shRNA-eGFP infusion. H.E. staining was used to evaluate skin lesion.

RESULTS

AEW treatment triggers spontaneous scratching and significantly increases the expression of NLRP1, ASC, and caspase-1 and the levels of IL-1β, IL-18, IL-6, and TNF-α in the spinal cord and the skin of mice. Spinal cord Nlrp1a knockdown prevents AEW-induced NLRP1 inflammasome assembly, TRPV1 channel activation, and spontaneous scratching behavior. Capsazepine, a specific antagonist of TRPV1, can also inhibit AEW-induced inflammatory response and scratching behavior. Furthermore, elderly mice and female mice exhibited more significant AEW-induced scratching behavior than young mice and male mice, respectively. Interestingly, AEW-induced increases in the expression of NLRP1 inflammasome complex and the levels of inflammatory cytokines were more remarkable in elderly mice and female mice than in young mice and male mice, respectively.

CONCLUSIONS

Spinal cord NLRP1 inflammasome-mediated inflammatory response contributes to dry skin-induced chronic itch by TRPV1 channel, and it is also involved in age and sex differences of chronic itch. Inhibition of NLRP1 inflammasome may offer a new therapy for dry skin itch.

Interventions for chronic pruritus of unknown origin

BACKGROUND

Pruritus is a sensation that leads to the desire to scratch; its origin is unknown in 8% to 15% of affected patients. The prevalence of chronic pruritus of unknown origin (CPUO) in individuals with generalised pruritus ranges from 3.6% to 44.5%, with highest prevalence among the elderly. When the origin of pruritus is known, its management may be straightforward if an effective treatment for the causal disease is available. Treatment of CPUO is particularly difficult due to its unknown pathophysiology.

OBJECTIVES

To assess the effects of interventions for CPUO in adults and children.

SEARCH METHODS

We searched the following up to July 2019: Cochrane Skin Group Specialised Register, CENTRAL, MEDLINE, Embase, and trials registries. We checked the reference lists of included studies for additional references to relevant trials.

SELECTION CRITERIA

We sought to include randomised controlled trials and quasi-randomised controlled trials that assessed interventions for CPUO, as defined in category VI ('Other pruritus of undetermined origin, or chronic pruritus of unknown origin') of the International Forum for the Study of Itch (IFSI) classification, in children and adults. Eligible interventions were non-pharmacological or topical or systemic pharmacological interventions, and eligible comparators were another active treatment, placebo, sham procedures, or no treatment or equivalent (e.g. waiting list).

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane. Our primary outcomes were 'Patient- or parent-reported pruritus intensity' and 'Adverse events'. Our secondary outcomes were 'Health-related quality of life', 'Sleep disturbances', 'Depression', and 'Patient satisfaction'. We used GRADE to assess the certainty of evidence.

MAIN RESULTS

We found there was an absence of evidence for the main interventions of interest: emollient creams, cooling lotions, topical corticosteroids, topical antidepressants, systemic antihistamines, systemic antidepressants, systemic anticonvulsants, and phototherapy. We included one study with 257 randomised (253 analysed) participants, aged 18 to 65 years; 60.6% were female. This study investigated the safety and efficacy of three different doses of oral serlopitant (5 mg, 1 mg, and 0.25 mg, once daily for six weeks) compared to placebo for severe chronic pruritus; 25 US centres participated (clinical research centres and universities). All outcomes were measured at the end of treatment (six weeks from baseline), except adverse events, which were monitored throughout. A pharmaceutical company funded this study. Fifty-five per cent of participants suffered from CPUO, and approximately 45% presented a dermatological diagnosis (atopic dermatitis/eczema 37.3%, psoriasis 6.7%, acne 3.6%, among other diagnoses). We unsuccessfully attempted to retrieve outcome data from study authors for the subgroup of participants with CPUO. Participants had pruritus for six weeks or longer. Total study duration was 10 weeks. Participants who received serlopitant 5 mg may have a greater rate of relief of patient-reported pruritus intensity as measured by the visual analogue scale (VAS; a reduction in VAS score indicates improvement) compared to placebo (126 participants, risk ratio (RR) 2.06, 95% confidence interval (CI) 1.27 to 3.35; low-certainty evidence). We are uncertain of the effects of serlopitant 5 mg compared to placebo on the following outcomes due to very low-certainty evidence: adverse events (127 participants; RR 1.48, 95% CI 0.87 to 2.50); health-related quality of life (as measured by the Dermatology Life Quality Index (DLQI); a higher score indicates greater impairment; 127 participants; mean difference (MD) -4.20, 95% CI -11.68 to 3.28); and sleep disturbances (people with insomnia measured by the Pittsburgh Sleep Symptom Questionnaire-Insomnia (PSSQ-I), a dichotomous measure; 128 participants; RR 0.49, 95% CI 0.24 to 1.01). Participants who received serlopitant 1 mg may have a greater rate of relief of patient-reported pruritus intensity as measured by VAS compared to placebo; however, the 95% CI indicates that there may also be little to no difference between groups (126 participants; RR 1.50, 95% CI 0.89 to 2.54; low-certainty evidence). We are uncertain of the effects of serlopitant 1 mg compared to placebo on the following outcomes due to very low-certainty evidence: adverse events (128 participants; RR 1.45, 95% CI 0.86 to 2.47); health-related quality of life (DLQI; 128 participants; MD -6.90, 95% CI -14.38 to 0.58); and sleep disturbances (PSSQ-I; 128 participants; RR 0.38, 95% CI 0.17 to 0.84). Participants who received serlopitant 0.25 mg may have a greater rate of relief of patient-reported pruritus intensity as measured by VAS compared to placebo; however, the 95% CI indicates that there may also be little to no difference between groups (127 participants; RR 1.66, 95% CI 1.00 to 2.77; low-certainty evidence). We are uncertain of the effects of serlopitant 0.25 mg compared to placebo on the following outcomes due to very low-certainty evidence: adverse events (127 participants; RR 1.29, 95% CI 0.75 to 2.24); health-related quality of life (DLQI; 127 participants; MD -5.70, 95% CI -13.18 to 1.78); and sleep disturbances (PSSQ-I; 127 participants; RR 0.60, 95% CI 0.31 to 1.17). The most commonly reported adverse events were somnolence, diarrhoea, headache, and nasopharyngitis, among others. Our included study did not measure depression or patient satisfaction. We downgraded the certainty of evidence for all outcomes due to indirectness (only 55% of study participants had CPUO) and imprecision. We downgraded outcomes other than patient-reported pruritus intensity a further level due to concerns regarding risk of bias in selection of the reported result and some concerns with risk of bias due to missing outcome data (sleep disturbances only). We deemed risk of bias to be generally low.

AUTHORS' CONCLUSIONS

We found lack of evidence to address our review question: for most of our interventions of interest, we found no eligible studies. The neurokinin 1 receptor (NK1R) antagonist serlopitant was the only intervention that we could assess. One study provided low-certainty evidence suggesting that serlopitant may reduce pruritus intensity when compared with placebo. We are uncertain of the effects of serlopitant on other outcomes, as certainty of the evidence is very low. More studies with larger sample sizes, focused on patients with CPUO, are needed. Healthcare professionals, patients, and other stakeholders may have to rely on indirect evidence related to other forms of chronic pruritus when deciding between the main interventions currently used for this condition.

Generalized chronic itch induced by small-fibre neuropathy: clinical profile and proposed diagnostic criteria

BACKGROUND

Small-fibre neuropathy (SFN) is a known cause for pain, however, it may be also associated with chronic itch. The clinical profile of chronic itch due to SFN is poorly defined and accordingly under-diagnosed in clinical care.

OBJECTIVES

To establish the clinical profile of patients with SFN and to propose diagnostic criteria for this patient population.

METHODS

Clinical data from patients diagnosed with SFN [chronic generalized itch and reduced intraepidermal nerve fibre density (IENFD)] were analysed retrospectively.

RESULTS

A total of 142 patients (60 females, median age: 62.5 years) were included. Patients reported daily, moderate to severe itch intensity scores occurring mostly in attacks (62.5%). Only 11 patients experienced exclusively itch, while the remaining patients (92%) reported pruralgia (itch along with painful sensations). Burning (50%), a sensation like needle pricks (46%) and tingling (45%) were the sensory symptoms reported by most patients. Cold or ice application led to an alleviation of the symptoms. The IENFD did not correlate with itch intensity; however, patients with a severely reduced IENFD (<30% of the normative cut-off value) reported more frequently sharp, spiky and drilling sensations compared to the remaining patients. The quality of life was moderately impaired and correlated with itch intensity, whereas anxiety and depression scores were low.

CONCLUSIONS

Onset of pruralgia on normal appearing skin, occurrence in attacks and symptomatic alleviation with cold/ice application should alert physicians for a possible neuropathic SFN-related origin of itch. A reduced IENFD can confirm the diagnosis of SFN.

Racial and Gender Differences in the Presentation of Pruritus

Background: Pruritus is a common disease symptom with a variety of etiologies known to reduce patient quality of life. We aimed to characterize the racial and gender differences in the presentation of pruritus for itch-related patient visits both within a single institution and nationally. Methods: Cross sectional study of patients ≥ 18 years old seen at Johns Hopkins Health System between 1/1/12 and 1/1/18. Results were compared to data from 2005–2011 from the National Ambulatory Medical Care Survey (NAMCS) and the National Health Ambulatory Medical Care Survey (NHAMCS). Results: Our findings indicate that itch patients at JHHS (n = 18,753) were more likely to be black compared to white patients (37% vs. 19%, p < 0.01) when compared to patients without itch—a trend also noted nationally based on data from NAMCS/NHAMCS (26% vs. 21%, p = 0.05). Black itch patients are also more likely to be diagnosed with prurigo nodularis (OR 2.37, p < 0.0001), lichen planus (OR 1.22, p < 0.0001), and atopic dermatitis OR 1.51, p < 0.0001). Female itch patients are more likely to be diagnosed with autoimmune (OR 1.66, p < 0.0001) and psychiatric comorbidities (OR 1.2–1.8, p < 0.0001) than male itch patients. When compared to black itch patients nationally, white itch patients were more likely to visit a dermatologist (29% vs. 18%, p = 0.028). Our data can identify associated conditions and demographic differences but are unable to support a causal relationship. Conclusions: Black and female patients are more likely to present with pruritus, a symptom associated with comorbidities such as prurigo nodularis, lichen planus, atopic dermatitis, and psychiatric conditions.

Characterization of cowhage-induced pruritus in inflamed and non-inflamed skin

BACKGROUND AND OBJECTIVE

Pruritus is a major symptom of many inflammatory diseases and impacts greatly the quality of life in patients. We aimed to specify the characteristics of experimentally induced pruritus in normal skin and in experimentally induced inflammatory dermatitis in healthy volunteers.

METHODS

Skin inflammation was induced by the repeated application of sodium lauryl sulphate (SLS 2%) on the volar forearms of 30 healthy volunteers. Inflammatory dermatitis intensity was assessed using the eczema score adapted from Frosch and Kligman. Non-histaminergic pruritus was induced by cowhage spicules rubbed on the volar forearms and recorded for 30 min on a 10-cm visual analogue scale (VAS) in both non-inflamed and inflamed skin.

RESULTS

Induction of inflammatory dermatitis by SLS resulted in a mild inflammatory dermatitis with an inflammation score of 2.3 ± 0.1 within 7 days of treatment. Cowhage-induced pruritus was of markedly higher intensity (P < 0.001), and all but two individuals had higher maximum pruritus intensity in inflamed skin as compared to non-inflamed skin, whereas the kinetics of the pruritus response were similar. The quality of cowhage-induced pruritus was significantly different with more 'burning' and 'painful sensations' in inflamed skin (P < 0.01). Maximum pruritus intensity in inflamed skin strongly correlated with maximum pruritus intensity in non-inflamed skin (r = 0.51, P = 0.004). Skin hydration, skin barrier integrity and dermatitis severity did not correlate with pruritus intensity.

CONCLUSION

Taken together, pruritus in inflamed skin is perceived as more intense, painful and burning. This may explain, in part, why pruritus is a major driver of quality-of-life impairment in patients with chronic inflammatory skin conditions such as atopic dermatitis.

Sex differences in the pharmacology of itch therapies-a narrative review

BACKGROUND

Chronic itch is the most common skin-related condition, associated with a high psychosocial and economic burden. In recent years, increasing evidence of sex differences in the perception, clinical presentation and treatment requirements of itch points towards potential benefits when using sex-adapted therapies. It is well-known that body composition, absorption, metabolism, elimination and adverse drug reactions (ADRs) differ between sexes, but only little is known about the impact of sex in the pharmacology of itch treatments, which could help to rationalise sex-adapted treatment strategies.

AIM

To evaluate and review sex effects in the pharmacokinetics and /-dynamics of drugs used to treat itch.

METHODS

In this narrative review we performed a PubMed and MEDLINE (Ovid) search using the terms (itch OR pruritus) AND (gender OR sex) AND (drug OR medication OR pharmacokinetics OR pharmacodynamics). Additional searches were performed for the topical and systemic drugs recommended by the European Guideline on Chronic Pruritus.

RESULTS

We found numerous reports with variable levels of evidence of sex effects with respect to the pharmacokinetics and/or pharmacodynamics of 14 drug classes used for the treatment of itch, including a total of 19 systemic and 3 topical drugs. Women seem to present higher plasma levels of several drugs used in itch treatment, including tri- and tetracyclic antidepressants (e.g. doxepin, amitriptyline, mirtazapine), serotonin reuptake inhibitors (e.g. paroxetine, sertraline, fluoxetine), immunosuppressive drugs (e.g. cyclosporine, mycophenolate mofetil), serotonin receptor antagonists (e.g. ondansetron) and betablockers (e.g. propranolol). Adverse drug reactions (ADRs) were generally more common in women. Being female was reported to be an independent risk factor for QTc-prolongation associated with antihistamines and tetracyclic antidepressants. Additionally, women seem to be more prone to sedative effects of antihistamines, and to suffer from a higher frequency as well as severity of side effects with systemic calcineurin inhibitors, opioid agonists, and opioid antagonists. Women were also sensitised more often to topically applied drugs. Of note, apart from only one experimental study with capsaicin, none of these reports were designed specifically to assess the effect of sex (and gender) in the treatment of itch.

DISCUSSION/CONCLUSION

Our review supports previous reports that sex is of importance in the pharmacokinetics and /-dynamics of several drugs used to treat itch although those drugs were mostly evaluated for non-itch indications. However, the results are limited by methodological limitations evident in most studies such as underrepresentation of women in clinical trials. This emphasises the need to study the impact of sex (and gender) in future itch trials to yield better outcomes and prevent ADRs in both sexes.

Multidimensional pruritus assessment in hemodialysis patients

Background

Pruritus is a distressing, life-limiting symptom in chronic renal failure, affecting 40% of patients. This study aimed to determine uremic pruritus prevalence and investigate the multidimensional impact on hemodialysis patients.

Methods

This descriptive study was performed between March and June 2016. The study included 181 patients undergoing hemodialysis session, who reported pruritus in the prior month. Data were collected using the 5-D Itch Scale, which assesses pruritus based on 5 dimensions, i.e., degree, duration, direction, disability, and distribution, with a total score ranging from 5 (no itching) to 25 (maximum severity).

Results

Pruritus prevalence was 49.3%. Patients had a mean score of 13.97 ± 4.11 (moderate severity). The daily duration was 6–12 h (40.3%), with direction “a little bit better but still present” (38.7%) and distribution on the “back, upper arms, chest, and abdomen.” Patients sleep, social life/leisure time, housework and errand were impacted “occasionally”. The score was higher in patients aged ≥65 years, those on hemodialysis for ≥15 or more years, and those undergoing afternoon hemodialysis. The duration of itching was significantly shorter in employed patients.

Conclusion

Assessment and management of itching symptoms in chronic renal failure are a clinical priority both for patients and for health care professionals. The results of this study highlight the importance of multidimensional assessment and support the need for development of standardized and patient-specific symptom management.

Humanistic burden of chronic pruritus in patients with inflammatory dermatoses: Results of the European Academy of Dermatology and Venereology Network on Assessment of Severity and Burden of Pruritus (PruNet) cross-sectional trial

BACKGROUND

Chronic pruritus is a multifactorial, challenging symptom of global relevance.

OBJECTIVE

The European Academy of Dermatology and Venereology Network on Assessment of Severity and Burden of Pruritus (PruNet) investigation aimed to analyze the severity and humanistic burden of chronic pruritus in patients suffering from inflammatory dermatoses across Europe.

METHODS

Prospectively collected routine data on 552 patients (with atopic dermatitis, contact dermatitis, prurigo nodularis, psoriasis vulgaris, lichen planus, or mycosis fungoides [pruritus numeric rating scale score ≥3]) from 9 European centers (in Austria, France, Germany, Italy, Poland, Russia, Spain, Switzerland, and Turkey) were analyzed by univariate and multivariate variance analyses of various itch characteristics and quality of life (as measured by the Dermatology Life Quality Index and the ItchyQoL).

RESULTS

Duration, frequency, and intensity of pruritus (according to a numeric rating scale and visual analog scale) and related impairment of quality of life differed between European centers and dermatologic diagnoses (P < .05). The country in which the center was located had a greater impact on how patients evaluated pruritus intensity and quality of life than diagnosis did (P < .001).

LIMITATIONS

One center per country was included.

CONCLUSION

The humanistic burden of chronic pruritus in patients with inflammatory dermatoses is high. European cross-cultural factors may have a stronger influence than a specific dermatologic diagnosis on how patients rate intensity of pruritus and quality of life.

Cross-European validation of the ItchyQoL in pruritic dermatoses

BACKGROUND

Chronic pruritus (CP) is a frequently occurring symptom in inflammatory dermatoses, causing a high burden and limitations to health-related quality of life (HRQoL).

OBJECTIVE

The ItchyQoL was developed to assess the impairment to HRQoL in patients with CP. However, it has only been validated in English and German. Here, we report the validation in several languages across Europe.

METHODS

After professional translation, the versions of ItchyQoL were digitized for use as a tablet application. Validation was performed in clinics for dermatology in Austria, France, Germany, Italy, Poland, Russia, Spain, Switzerland and Turkey.

RESULTS

Five hundred and thirty-five patients with either contact dermatitis, chronic prurigo - nodular type, psoriasis vulgaris, lichen planus or mycosis fungoides/Sézary syndrome and with CP ≥ 3 on the numerical rating scale were included. ItchyQoL showed a high level of consistency (Cronbach's-α, all: 0.95) and test-retest reliability (intraclass correlation: 0.91). It strongly correlated with the Dermatology Life Quality Index (r = 0.72, P < 0.001) and moderately correlated with itch intensity scales in the study population (visual analogue scale r = 0.46; numerical rating scale r = 0.51; verbal rating scale r = 0.51, for all: P < 0.001).

CONCLUSION

ItchyQoL is now also validated in French, Italian, Polish, Russian, Spanish and Turkish and can be used in clinical trials in countries speaking these languages.

A systematic review of evidence-based treatments for prurigo nodularis

Prurigo nodularis is a chronic dermatologic condition involving the development of multiple cutaneous nodules in the setting of intractable pruritus. Given emerging treatment options for this difficult-to-treat condition, a current review of therapeutics is needed. A systematic review was performed for clinical studies investigating prurigo nodularis treatment published from 1990 to present including ≥5 subjects. A total of 35 articles were assigned a level of evidence according to the Oxford Center for Evidence-based Medicine. All 5 studies investigating topical agents, including corticosteroids, calcineurin inhibitors, calcipotriol, and capsaicin, conveyed some beneficial effect with level of evidence 2b or higher. Six of 8 reports investigating photo- and photochemotherapy achieved levels of evidence 2b or greater and showed good partial response rates. Thalidomide was studied by 6 reports providing evidence of good symptom response, only 2 of which were rated level 2b or greater. Cyclosporine and methotrexate have demonstrated benefit in 4 combined studies, albeit with level 4 evidence. Pregabalin, amitriptyline, paroxetine, fluvoxamine, and neurokinin-1 receptor antagonists have demonstrated promising evidence in 5 level 2b studies. Higher-powered studies and additional randomized controlled trials are needed for the evaluation of safe and efficacious systemic treatment options for prurigo nodularis.

Xerosis cutis and associated co-factors in women with prurigo nodularis

BACKGROUND

Current data regarding the associated factors of prurigo nodularis are still uncertain, except for atopic predisposition.

OBJECTIVES

The purposes of this study were to (1) determine the frequencies of xerosis and other accompanying diseases of female patients with prurigo nodularis; (2) compare the demographic, clinical and accompanying disease characteristics by grouping these patients according to whether they have associated xerosis (who were subsequently subgrouped as atopic or non-atopic) or not.

METHODS

In this retrospective descriptive study, 80 females with PN were categorized according to the accompanying diseases (dermatological, systemic, neurological, psychogenic, mixed, or undetermined origin).

RESULTS

A total of 45 associated co-factors including dermatological in 63 (78.8%), systemic in 57 (71.3%), psychological in 33 (41.3%) and neurological co-factors in 14 (17.5%) of all patients with prurigo nodularis were detected. Xerosis was observed in 48 (60%) patients (non-atopic co-factors in 66.7% of them). The ratio of patients with mixed co-factors, dermatological+systemic co-factors and dermatological+systemic+psychological co-factors were found to be significantly higher in patients with xerosis compared to those without xerosis.

STUDY LIMITATIONS

Our study has certain limitations such as the absence of an age-matched control group, absence of follow-up data and the fact that the diagnosis of xerosis has not been based on objective methods.

CONCLUSIONS

Xerosis has been identified in more than half of the patients with PN and it has been determined that in most patients xerosis is associated especially with diabetes mellitus and other conditions related to prurigo nodularis.

Different perception levels of histamine-induced itch sensation in young adult mice

Itch is an unpleasant sensation that evokes behavioral responses such as scratching the skin. Interestingly, it is conceived that the perception of itch sensation is influenced by age. Indeed, accumulating evidence supports the idea that even children or younger adults show distinctive itch sensation depending on age. This evidence implies the presence of a mechanism that regulates the perception of itch sensation in an age-dependent fashion. Therefore, the purpose of the present study was to investigate a putative mechanism for the age-dependent perception of itch sensation by comparing histamine-induced scratching behaviors in 45-day old (D45) and 75-day old male "young adult" mice. The results indicated that, following histamine administration, the D75 mice spent a longer time scratching than D45 mice. However, the intensity of the calcium influx induced by histamine in primary culture of dorsal root ganglia (DRG) neurons was not different between D45 and D75 mice. Moreover, no apparent difference was observed in mRNA levels of a characteristic His-related receptor and ion channel. In contrast, the mRNA levels of Toll-Like Receptor 4 (TLR4) were increased approximately by two-fold in D75 DRG compared with D45 DRG. Additionally, D75-derived DRG neurons exhibited enhanced intracellular calcium increase by lipopolysaccharide (LPS, a TLR4 agonist) than those of D45 mice. Furthermore, intensities of calcium influx induced by histamine were significantly potentiated when co-treated with LPS in D75 DRG neurons, but not in those of D45 mice. Thus, it appears that D75 mice showed enhanced histamine-induced scratching behaviors not by increased expression levels of histamine-related genes, but probably due to augmented TLR4 expression in DRG neurons. Consequently, the current study found that different perception levels of histamine-induced itch sensation are present in different age groups of young adult mice.

Differences Between Men and Women in Chronic Scratching: A Psychodermatologic Study in Lichen Simplex Chronicus

INTRODUCTION

Chronic scratching is common to many skin disorders. Being a female and presenting a high level of psychopathology are risk factors for chronic scratching. Yet, it is unclear why. Certain personality characteristics that are more prevalent in women are also known to influence emotional states (i.e. emotional tension).

OBJECTIVE

The present study aims to explore whether these personality styles might help understand why gender and emotional distress are associated with scratching.

MATERIAL AND METHODS

We compared the personality patterns of 103 patients (69.9% women) diagnosed with Lichen Simplex Chronicus, against a sample of healthy individuals.

RESULTS

Significant differences were found in the personality styles of men and women with LSC. Women were more pessimistic, oriented to fulfil the needs of others, traditional, insecure, submissive, and reserved, with moderate (d=.43) to strong (d=.96) size effects ranges. Some of these differences, such as in traditionalism, dutifulness, other-orientation, and pessimism, were also observed when compared with healthy men and women, with small (d=.03) to moderate (d=.47) size effects ranges.

CONCLUSIONS

These psychological factors may help explain the mechanisms underlying gender differences in chronic scratching, at least in Lichen Simplex Chronicus. The findings might open new avenues for research and treatment.