What is new in the psychology of chronic itch?

Annexin 1 Reduces Dermatitis-Induced Itch and Cholestatic Itch through Inhibiting Neuroinflammation and Iron Overload in the Spinal Dorsal Horn of Mice

The unclear pathogenesis of chronic itch originating from several systemic disorders poses challenges to clinical intervention. Recent studies recapitulate the spinal neurocircuits associated with neuroinflammation and synaptic plasticity responsible for pruriceptive sensations. The resolution of nociception and inflammation by Annexin 1 (ANXA1) has been identified. Given that pain and itch share many neural mechanisms, we employed two mice models of chronic itch to study the underlying targets and therapeutic potential of ANXA1, comprising allergic contact dermatitis-induced itch and cholestatic itch. Herein, we report that spinal expression of ANXA1 is down-regulated in mice with dermatitis-induced itch and cholestatic itch. Repetitive injections of ANXA1-derived peptide Ac2-26 (intrathecal, 10 μg) reduce itch-like scratching behaviors following dermatitis and cholestasis. Single exposure to Ac2-26 (intrathecal, 10 μg) alleviates the established itch phenotypes. Moreover, systemic delivery of Ac2-26 (intravenous, 100 μg) is effective against chronic dermatitis-induced itch and cholestatic itch. Strikingly, Ac2-26 therapy inhibits transferrin receptor 1 over-expression, iron accumulation, cytokine IL-17 release and the production of its receptor IL-17R, as well as astrocyte activation in the dorsal horn of spinal cord in mouse with dermatitis and cholestasis. Pharmacological intervention with iron chelator deferoxamine impairs chronic itch behaviors and spinal iron accumulation after dermatitis and cholestasis. Also, spinal IL-17/IL-17R neutralization attenuates chronic itch. Taken together, this current research indicates that ANXA1 protects against the beginning and maintenance of long-term dermatitis-induced itch and cholestatic itch, which may occur via the spinal suppression of IL-17-mediated neuroinflammation, astrocyte activation and iron overload.

Mind and skin: Exploring the links between inflammation, sleep disturbance and neurocognitive function in patients with atopic dermatitis

Atopic dermatitis (AD) is a chronic, pruritic and inflammatory, dry skin condition with many known comorbidities. These include airway disease, food allergies, atopic eye disease and autoimmune conditions. Furthermore, there is often significant sleep disturbance as well as increased psychological distress and mental health problems. Severe AD therefore often has a significant impact on the quality of life of both patients and their families. In this review we discuss recent findings on the putative links between AD, its association with itch, sleep disturbance and neuropsychiatric morbidity, including the role of inflammation in these conditions. Itch was thought to predominantly drive sleep disruption in AD. We now understand changes in sleep influence immune cell distribution and the associated inflammatory cytokines, which suggests a bidirectional relationship between AD and sleep. We also increasingly recognize inflammation as a key driver in psychological symptoms and disorders. The link between cutaneous, systemic and possible brain inflammation could at least in part be driven by the sleep deprivation and itch-driven neuronal proliferation seen in AD.

Subliminal attentional bias modification training for itch

Introduction

Itch is unpleasant and induces the urge to scratch. This is adaptive to remove the itch-inducing stimulus from the skin. Accordingly, itch draws attention to protect our bodily integrity. Recent studies investigated whether attention is preferentially drawn towards its location, i.e., attentional bias (AB), and also whether this bias could be changed in healthy individuals. So far, results are mixed concerning the existance of an attentional bias towards itch stimuli in healthy individuals as well as the impact of modifications. However, available studies have typically focused on conscious processing and might miss preconscious aspects of attention and potential biases at these stages.

Methods

This study included 117 healthy individuals who underwent a subliminal Attentional Bias Modification (ABM)- training for itch based on a dot-probe paradigm with itch- related pictures. Participants were randomly assigned to a training towards itch group, a training away from itch group and a control group. This was done by manipulating the itch-target congruency of the dot-probe task during a training block. Pre- and post-training assessments were regular dot-probe tasks. Exploratorily, also attentional inhibition, cognitive flexibility and itch-related cognitions were assessed. Lastly, participants received an itchy stimulus on the inner forearm before and after the ABM-training to assess potential effects on itch sensitivity.

Results

Results showed no AB towards itch across groups at baseline, i.e., pre-training, but an AB away from itch, hence, avoidance of itch, post-training. Further analyses showed that this effect was driven by an attentional bias away from itch in the control group, while there were no significant effects in the experimental groups. There was no effect on itch sensitivity.

Conclusion

These findings are in line with recent studies on conscious ABM-training for itch and pain that also did not find significant training effects. Therefore, it is suggested that the field of AB might need to reconsider the current assessment of AB. Moreover, AB is probably a dynamic process that is highly dependent on current itch-related goals and relevance of itch in a specific situation. This suggests that processes probably differ in patients with chronic itch and that also ABM-training might work differently in these populations.

Clinical trial registration

https://trialsearch.who.int/Trial2.aspx?TrialID=NTR7561, identifier NTR7561.

Learned Nocebo Effects on Cutaneous Sensations of Pain and Itch: A Systematic Review and Meta-analysis of Experimental Behavioral Studies on Healthy Humans

OBJECTIVE

In past decades, the field of nocebo research has focused on studying how sensory perception can be shaped by learning. Nocebo effects refer to aggravated sensory experiences or increased sensitivity to sensations such as pain and itch resulting from treatment-related negative experiences. Behavioral conditioning and verbal suggestions of a negative treatment outcome may aggravate pain and itch perception. Gaining a comprehensive view of the magnitude of nocebo effects and contributing factors will help steer nocebo research toward fruitful directions for understanding complex sensory phenomena.

METHODS

We conducted a systematic review and meta-analysis of a total of 37 distinct experimental nocebo studies on healthy participants (all published in English between 2008 and 2021), with four separate meta-analyses for nocebo effects on pain or itch. We conducted subgroup analyses and meta-regression on factors such as type and intensity of sensory stimuli, and length of conditioning paradigms.

RESULTS

This meta-analysis showed that, on average, effect sizes of nocebo effects were moderate to large (Hedges g between 0.26 and 0.71 for the four primary outcomes). The combination of conditioning and verbal suggestions yielded stronger nocebo responses on pain in particular. Subgroup analyses, including factors such as the type of sensory stimulation, did not explain the moderate heterogeneity in nocebo magnitudes between different studies. Risk of bias was generally low and was not related to nocebo magnitudes either.

CONCLUSIONS

We discuss these results in relation to the role of conditioning and aversive learning, and we recommend more consistency in designing and reporting nocebo experiments.

[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.

Induction and generalization of nocebo effects on itch

Nocebo effects, that is, negative treatment outcomes due to negative expectancies, can increase itch. Moreover, indirect evidence has shown that nocebo hyperknesis can generalize to another itch modality. Knowledge on response generalization can help to prevent and decrease negative effects. The aims of this study were to investigate (1) the efficacy of inducing nocebo effects on cowhage‐evoked itch via verbal suggestions and (2) whether these effects can generalize to (2a) mechanically evoked touch and (2b) mechanically evoked itch. Forty‐four healthy participants watched a video suggesting that a nocebo solution increases cowhage‐evoked itch and that a control solution does not affect itch. Subsequently, cowhage, mechanical itch, and mechanical touch stimuli were applied. Nocebo effects were measured as the difference in both mean and peak of the outcomes itch and urge to scratch between nocebo and control trials. Main analyses revealed significant nocebo effects on mean and peak itch for all stimuli. For urge to scratch, a significant nocebo effect was only observed for mechanical touch (peak). As mechanical stimuli did not induce pure sensations as planned, posthoc sensitivity analyses were run for mechanical stimuli that individually induced either touch or itch at baseline. These analyses showed similar results for generalization to mechanical itch, but generalization to mechanical touch was non‐significant. This study showed that merely verbal suggestion can induce nocebo effects on cowhage‐evoked itch and that these effects can generalize to another itch modality. Future studies may examine how to prevent negative experiences from generalizing to subsequent encounters.

Epidemiological factors in patients with dermatologic conditions referring to the clinic of traditional Persian Medicine: A cross-sectional study

INTRODUCTION

Many patients with chronic diseases often use traditional medicine, as well as conventional medicine. The aim of this study was to evaluate the epidemiological factors of patients with dermatological conditions referring to traditional Persian Medicine (TPM) clinic.

MATERIALS AND METHODS

In this cross-sectional study, we reviewed all the patients' medical documents, from March 2018 to March 2019, with dermatological conditions referred to the TPM clinic at Shiraz, Southern Iran. Then, the epidemiological factors of the patients were recorded in a researcher-made data collection form. SPSS software version 22 was used to analyse the data.

RESULTS

Overall, 631 patients consisting of 151 (23.9%) males and 580 (76.1%) females were enrolled in the study. Most of the patients were aged from 31 to 40 years, 347 (55%) patients were married, and most of them were housewives. The frequency of patients in the spring was higher than in other seasons. Furthermore, most of the patients were university educated. Acne, eczema and hair loss were the three most complaints of the patients who were referred to the traditional medicine clinic. 301(47.7%) patients reported gastrointestinal problems as another complaint concomitant with their skin problems.

CONCLUSION

It seems that women with skin problems, including acne, eczema, and hair loss, were more likely to refer to the TPM clinic. Therefore, the development of TPM clinics in the dermatology field as a scientific and academic approach can be effective in the treatment of patients with dermatological conditions accompanied by traditional medicine.

Attentional Bias Modification Training for Itch: A Proof-of-Principle Study in Healthy Individuals

Itch draws our attention to allow imposing action against bodily harm (e.g., remove insects). At the same time, itch is found to interfere with ongoing tasks and daily life goals. Despite the key role of attention in itch processing, interventions that train individuals to automatically disengage attention from itch cues are lacking. The present proof-of-principle attention bias modification (ABM) training study was aimed at investigating whether attention to itch as well as sensitivity to mild itch can be changed. Healthy volunteers were randomized over three ABM-training conditions. Training was done via a modified pictorial dot-probe task. In particular, participants were trained to look away from itch stimuli (n = 38), toward itch stimuli (n = 40) or not trained toward or away from itch at all (sham training, n = 38). The effects of the ABM-training were tested primarily on attention to itch pictures. Secondarily, it was investigated whether training effects generalized to alterations in attention to itch words and mechanical itch sensitivity. The ABM-training did not alter attention toward the itch pictures, and there was no moderation by baseline levels of attention bias for itch. Also, attention bias to the itch words and itch sensitivity were not affected by the ABM-training. This study was a first step toward trainings to change attention toward itch. Further research is warranted to optimize ABM-training methodology, for example increasing motivation of participants. Eventually, an optimized training could be used in patient populations who suffer most from distraction by their symptoms of itch.

Clinical Trial Registration: Identifier: NL6134 (NTR6273). The website URL is: https://www.trialregister.nl/

Development and psychometrics of the English version of the Itch Cognitions Questionnaire

Background

The aim of this study was to validate the English version of the Itch Cognition Questionnaire in a sample of patients with chronic itch due to psoriasis or atopic dermatitis. An English-language version of an instrument assessing itch-related cognitions is needed since cognitions can contribute to a worsening of itch, and chronic itch is prevalent in English-speaking counties and internationally.

Methods

The German Itch Cognitions Questionnaire was translated into English, and cognitive interviewing was conducted to finalize item wording. Internal and test-retest reliability, item discrimination, responsiveness to change, and construct, convergent, and discriminant validity were assessed in a national sample of 137 individuals with chronic itch due to atopic dermatitis or psoriasis recruited online.

Results

Internal reliability was high with Cronbach’s alphas of 0.93 for the Catastrophizing subscale and 0.88–0.90 for Coping. The Pearson’s correlation assessing 1-month test-retest reliability for the Catastrophizing subscale was r = 0.62 and for the Coping subscale was r = 0.61. The corrected item-total correlation revealed that items were relatively consistent with the scores for the subscales (with correlations ranging from 0.58 to 0.79), indicating very good item discrimination. Results of factor analysis, convergent and discriminant, and responsiveness to change analyses provided evidence for validity.

Conclusions

This study showed good psychometric characteristics of the English version of the Itch Cognitions Questionnaire. We suggest that future studies investigate the use of the measure in clinical practice to assist with treatment planning and outcome assessment related to itch as well as address study limitations such as sampling and replication.

What is new in the psychology of chronic itch?

Itch is often regarded as unpleasant or bothersome and is accompanied by symptoms of distress and impairments in daily life. The biopsychosocial model of chronic itch describes how psychological factors can contribute to the improvement or exacerbation of chronic itch and related scratching behaviour. Recent research underlines the important role of cognitive-affective information processing, such as attention, affect and expectancies. This may not only play a role for acute itch states, but may particularly apply to the process of itch chronification, for example, due to the vicious cycle in which these factors shape the experience of itch. The present paper focuses on new insights into the relation between itch and the cognitive-affective factors of attention, affect and expectancies. These factors are thought to play a possible aggravating role in itch in the long term and have received increasing attention in the recent empirical literature on maintaining and exacerbating factors for chronic physical symptoms. Possible psychophysiological and neurobiological pathways regarding these factors are discussed, as well as possible intervention methods.

Optimizing audiovisual itch induction: the role of attention and expectancy

Linked Article: Marzell et al. Br J Dermatol 2020; 182:1253–1261.