Role of personality and expectations for itch and scratching induced by audiovisual itch stimuli

Psychodermatology of Chronic Pruritus: An Overview of the Link Between Itch and Distress

Chronic pruritus (CP) is defined as an unpleasant sensation causing a desire to scratch and lasting > 6 weeks. It has a multifactorial etiology but is more frequently associated with chronic inflammatory dermatoses and systemic disorders. Psychogenic pruritus and neurological disorders are other less common etiologies, while, in some patients, it is idiopathic. CP appears to be processed by non-histaminergic pathway, contributing to its complexity and therapeutic challenge. Moreover, regardless of the etiology, it is multidimensional, including cognitive, motivational and affective components. There is a close link between psychological distress and pruritus, with particular clinical expression in chronic inflammatory dermatoses, involving the activation of the hypothalamic-pituitary-adrenal axis (and its cutaneous equivalent), the sympathetic nervous system, the release of hormones and peptides, the role of immune cells (T and B cells, macrophages) and immune-related cells in the skin (mast cells, dendritic cells and keratinocytes). Moreover, there is strong evidence that psychological factors influence the experience of pruritus. CP can also cause psychiatric disorders, including but not limited to anxiety and depression, and also lead to significant quality of life (QoL) impairment. Thereby, although a psychodermatological assessment should ideally be carried out in the context of a specific psychodermatology consultation, a brief mental health assessment could be part of the general dermatological approach to these patients. Considering that mental health, QoL and pruritus are closely linked, psychotherapeutic interventions and/or psychotropic drugs should thus be considered in some patients as an adjunct to the pharmacological treatment of CP.

Study protocol: Neuro-inflammatory parameters as mediators of the relationship between social anxiety and itch intensity: A cross-sectional, controlled laboratory study in patients with psoriasis and healthy skin controls

INTRODUCTION

Psoriasis (PSO) is a disease that in the majority of patients is accompanied by itch, which imposes a great burden and positively relates to anxiety. Social anxiety, a facet of anxiety associated with social withdrawal, may be a predictor of itch intensity in this patient group. Moreover, anxiety is linked to the secretion of neuroendocrine and inflammatory parameters such as substance P (SP), interleukin (IL)-6 and IL-17, which are also related to itch. In this research project, we investigate first, whether there is a direct relationship between social anxiety and itch intensity in patients with PSO and second whether the secretion of SP, IL-6 and IL-17 in the skin mediates this relationship. Additionally, PSO-patients are compared to healthy skin controls regarding their level of social anxiety, itch intensity and the secretion of SP, IL-6 and IL-17.

METHODS AND ANALYSES

For study 1, we aim to recruit 250 psoriasis patients and 250 healthy skin controls who complete questionnaires to assess social anxiety, itch intensity and control variables (e.g. sociodemographic variables and severity of PSO). A linear hierarchic regression will be used to determine whether social anxiety significantly contributes to itch intensity. In study 2, we plan to apply the suction blister method to 128 patients and healthy skin controls recruited from study 1 to determine SP, IL-6 and IL-17 in tissue fluid extracted from the skin. A mediation analysis will be conducted using the SPSS-macro PROCESS to test whether the relationship between social anxiety and itch is mediated by SP, IL-6 and IL-17.

TRIAL REGISTRATION NUMBERS

DRKS00023621 (study 1) and DRKS00023622 (study 2).

Can contagious itch be affected by positive and negative suggestions?

Contagious itch can be evoked by observing people scratching. Verbal suggestions about to-be-received itch can influence itch intensity, as shown by placebo research, but it is unknown whether this extends to contagious itch. The current study aimed to replicate prior findings that listening to scratching and rubbing sounds elicits contagious itch, and to investigate whether suggestions can modulate this process. Healthy participants (n = 140) received positive or negative suggestions about itch in response to the sounds (aimed to decrease or increase expected itch, respectively), or no specific suggestions as a control. Participants listened to a number of audio fragments with scratching and rubbing sounds. The amount of expected itch as well as itch sensation after each audio fragment were measured by self-report. Suggestions had no effect on the expected itch. Both rubbing and scratching sounds significantly elicited itch in all groups. Scratching sounds induced more itch than rubbing sounds exclusively in the control group. These findings indicate that short suggestions might be not effective enough to modify the expectations of people regarding contagious itch. Furthermore, suggestions modulate contagious itch to some degree, but not in the hypothesized direction. Potential similarities and differences in the neurobiological mechanisms of contagious itch and nocebo effects are discussed.

[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.

Do individual psychological characteristics predict induction and generalization of nocebo and placebo effects on pain and itch?

BACKGROUND

Nocebo and placebo effects, i.e., adverse or beneficial treatment effects, respectively, putatively due to expectancies can modulate pain and itch. These effects can generalize within the pain or itch modality. Predicting the induction and generalization of these effects can be helpful in clinical practice. This study aims to investigate whether psychological characteristics related to the fear-avoidance model predict the induction and generalization of nocebo and placebo effects on pain and itch in young healthy participants.

METHODS

Data from two previous experiments were analyzed. In Experiment 1, we induced nocebo and placebo effects on heat pain and tested generalization to pressure pain and to cowhage-evoked itch (n = 33 in a nocebo group, n = 32 in a placebo group). In Experiment 2, we induced nocebo effects on cowhage-evoked itch and tested generalization to mechanical itch and to mechanical touch (n = 44). Potential predictors were anxiety- and stress symptoms, attention to pain/itch, and pain/itch catastrophizing. Multiple regression analyses were performed.

RESULTS

For nocebo effects, none of the individual psychological characteristics significantly predicted induction of nocebo effects nor their generalization. For placebo effects, only less stress symptoms, lower attention to pain, and higher pain catastrophizing weakly predicted a stronger generalization of placebo effects from heat pain to pressure pain.

CONCLUSION

The tested psychological characteristics may not play an important role in the induction and generalization of nocebo and placebo effects in healthy individuals. However, firm conclusions cannot be drawn with the current sample. Future studies should validate findings in larger and more diverse samples.

Mindfulness as Predictor of Itch Catastrophizing in Patients With Atopic Dermatitis: Results of a Cross-Sectional Questionnaire Study

Itch and worry about itch are predominant symptoms in atopic dermatitis (AD). Mindfulness refers to paying attention in a certain way, non-judgementally and on purpose. In patients with chronic pain, which shares several similarities with chronic itch, a significant relationship between pain intensity, mindfulness and pain catastrophizing has been found. The aim of this study was to investigate whether itch intensity and mindfulness are related to itch catastrophizing in AD patients. Participants receiving treatment for AD (n = 155; 58 male; mean age: 46.5 ± 12 years) completed measures of itch-related catastrophizing (Itch Cognitions Questionnaire; ICQ) and mindfulness (Comprehensive Inventory of Mindfulness; CHIME) during their stay at a rehabilitation center in Borkum, Germany. In addition to other variables, their average itch intensity during the last 2 weeks was assessed by means of a visual analog scale. A positive relationship between itch intensity and itch catastrophizing was found (r = 0.409; p < 0.01). Moreover, the mindfulness scales “acting with awareness,” “accepting and non-judgemental orientation,” and “non-reactive orientation” were negatively related to itch catastrophizing. A linear regression analysis revealed that itch intensity in combination with “acting with awareness” was able to explain more than 27 % (corrected R² = 0.274; p < 0.001) of the variance of itch catastrophizing. Thus, itch intensity and certain facets of mindfulness were associated with itch catastrophizing in AD patients. Psychological interventions aiming to increase acting with awareness might have a buffering effect on itch catastrophizing, which in turn could lead to lower itch intensity in patients with AD. Future RCTs should test this hypothesis.

Skin and Psychosomatics - Psychodermatology today

Modern psychodermatology relies on the bio-psycho-social disease model in psychosomatics, according to which biological, psychological and social factors (on various levels, from molecules to the biosphere) play a major role in the disease pathogenesis through complex, non-linear interactions over the entire disease course. It is nowadays experimentally proven that "emotions get into the skin". Recent research shows close anatomical, physiological and functional connections between skin and nervous system, already known to be ontogenetically related. These connections are reflected in many skin diseases where psychological and somatic etiological factors are closely intertwined. A holistic approach by the physician should do justice to this interdependence; biological, psychological and social factors should be adequately taken into account when taking anamnesis, making a diagnosis and choosing a therapy. The "visibility" of the skin organ bestows dermatology a special position among the various other clinical subjects, and renders a holistic, psychosomatic approach to the patient that is particularly important. The life course belongs also to modern psychodermatological approaches. Based on the modern psychodermatology concept, other corresponding sub-areas such as psychogastroenterology, psychocardiology etc. have emerged. After the theoretical part of this article, some selected skin diseases are discussed in more detail from the psychosomatic point of view.

Matrix stimulation in chronic pruritus: A randomized controlled study

Chronic pruritus is one of the main symptoms in dermatology. We investigated a new intervention for chronic pruritus by neurostimulation through matrix electrodes. In this randomized controlled trial, 29 patients with chronic pruritus caused by a variety of dermatological diseases were allocated to an experimental group (EG; n = 14, 4-Hz neurostimulation of the itching area through matrix electrodes) or the control group (CG; n = 15, placement of matrix electrodes without neurostimulation). Outcome measures were the itching sensation as measured by a Numerical Rating Scale immediately after the intervention and the intermediate effect measured by the average itching sensation on the day before the intervention compared with the average itching sensation on day 1, 2 and 3 after the intervention. Regarding the short-term effect on itching, the anova showed a significant interaction effect for the 5-min stimulation with a larger reduction in the EG with a large effect size of d = 1.10. The average reduction in itching intensity was 78.2% for the EG compared with 34.3% for the CG. For the intermediate effect, no significant interaction was found (F = 1.721, P = 0.199). Comparing the itching sensation at day 0 with day 3, the interaction effect showed a statistical trend toward a greater reduction in the EG (F = 3.178, P = 0.086; statistical trend, d = 0.69). This study proved that neurostimulation through matrix electrodes is effective in the short-term reduction of itching in patients with chronic pruritus caused by dermatological diseases. Additional studies are needed with larger patient pools and covering longer study periods.

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.

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.

Placebo and Nocebo Effects Across Symptoms: From Pain to Fatigue, Dyspnea, Nausea, and Itch

Placebo and nocebo effects are, respectively, the helpful and harmful treatment effects that do not arise from active treatment components. These effects have thus far been researched most often in pain. It is not yet clear to what extent these findings from pain can be generalized to other somatic symptoms. This review investigates placebo and nocebo effects in four other highly prevalent symptoms: dyspnea, fatigue, nausea, and itch. The role of learning mechanisms (verbal suggestions, conditioning) in placebo and nocebo effects on various outcomes (self-reported, behavioral, and physiological) of these different somatic symptoms is explored. A search of experimental studies indicated that, as in pain, the combination of verbal suggestion and conditioning is generally more effective than suggestion alone for evoking placebo and nocebo effects. However, conditioning appears more and verbal suggestions less relevant in symptoms other than pain, with the exception of placebo effects on fatigue and nocebo effects on itch. Physiological measures, such as heart rate, lung function, or gastric activity, are rarely affected even when self-reported symptoms are. Neurobiological correlates are rarely investigated, and few commonalities appear across symptoms. Expectations generally predict placebo and nocebo effects for dyspnea and itch but seem less involved in fatigue and nausea. Individual characteristics do not consistently predict placebo or nocebo effects across symptoms or studies. In sum, many conclusions deriving from placebo and nocebo pain studies do appear to apply to other somatic symptoms, but a number of important differences exist. Understanding what type of learning mechanisms for which symptom are most likely to trigger placebo and nocebo effects is crucial for generalizing knowledge for research and therapies across symptoms and can help clinicians to optimize placebo effects in practice.

Itch and psyche: psychiatric aspects of pruritus

Itch, also referred to as pruritus, is an unpleasant cutaneous sensation provoking the desire to scratch. It is often an uncomfortable, subjective sensation responsible for decreased quality of life in a variety of psychodermatological conditions. Comorbid psychiatric conditions, including depression and anxiety, are frequently associated with itch and scratch cycle. The reciprocal and intricate relationship between the psyche and itch has been widely studied. The neurobiology of itch involves the complexity of specific mediators, itch-related neuronal pathways, and central processing of itch. The connection between itch and the psyche can be grouped under three headings: pruritic diseases with psychosocial sequelae, pruritic diseases aggravated by psychosocial factors, and psychiatric disorders causing pruritus. Itch and pain modulation go together in most circumstances and involve various substances including histamine, interleukins, protease-activated receptors, transient receptor potential receptors, opioids, and cannabinoids. The close interaction between keratinocytes and nerve endings modulating pain and itch also play a major role. Management of itch associated with its psychosomatic components is directed at an underlying cause and adopting a holistic approach to address not only dermatologic and somatosensory aspects, but also the cognitive, emotional, and psychosocial components. An integrated multidisciplinary team consisting of a dermatologist, psychiatrist, psychologist, and social worker is vital in addressing the multifaceted aspects of pruritus.

Brain Processing of Contagious Itch in Patients with Atopic Dermatitis

Several studies show that itch and scratching cannot only be induced by pruritogens like histamine or cowhage, but also by the presentation of certain (audio-) visual stimuli like pictures on crawling insects or videos showing other people scratching. This phenomenon is coined "Contagious itch" (CI). Due to the fact that CI is more profound in patients with the chronic itchy skin disease atopic dermatitis (AD), we believe that it is highly relevant to study brain processing of CI in this group. Knowledge on brain areas involved in CI in AD-patients can provide us with useful hints regarding non-invasive treatments that AD-patients could profit from when they are confronted with itch-inducing situations in daily life. Therefore, this study investigated the brain processing of CI in AD-patients. 11 AD-patients underwent fMRI scans during the presentation of an itch inducing experimental video (EV) and a non-itch inducing control video (CV). Perfusion based brain activity was measured using arterial spin labeling functional MRI. As expected, the EV compared to the CV led to an increase in itch and scratching (p < 0.05). CI led to a significant increase in brain activity in the supplementary motor area, left ventral striatum and right orbitofrontal cortex (threshold: p < 0.001; cluster size k > 50). Moreover, itch induced by watching the EV was by trend correlated with activity in memory-related regions including the temporal cortex and the (pre-) cuneus as well as the posterior operculum, a brain region involved in itch processing (threshold: p < 0.005; cluster size k > 50). These findings suggest that the fronto-striatal circuit, which is associated with the desire to scratch, might be a target region for non-invasive treatments in AD patients.

[Placebo response - Mechanisms and clinical applications]

Research on placebo responses has made major progress in recent years. Placebo responses are psychobiological events, which are created by the entire therapeutic context. They can appear at any time, not only in experimental and clinical settings. Several studies on analgesia-related placebo research showed that patients have higher placebo responses in comparison to healthy participants, which may also last longer. Expectations play a key role in placebo analgesia. They can be induced via three central psychological mechanisms: 1) expectation induced via instructions, 2) expectation induced via classical conditioning and 3) expectation induced via social learning. These mechanisms are controlled by neurobiological structures and modulate pain perception resulting in pain relief by positive expectations and increased pain by negative expectations, the so-called nocebo effect. There is an ongoing discussion that these psychological mechanisms may also play a central role in inducing and maintaining itch-reducing placebo responses. The current state of research suggests that placebo responses could be used in clinical contexts and should not be viewed as being in competition with medications but as an additive increase in efficacy of a pharmacological substance through specifically induced placebo responses. This targeted use is also possible within ethical guidelines. Important prerequisites are that the research results can be transferred from healthy participants to patients and that the placebo responses are reproducible.

[Psychological aspects of pruritus and therapy options]

BACKGROUND

Besides biological factors, which cause or influence chronic pruritus, more and more attention has recently also been paid to psychological and psychoneuroimmunological factors which uphold the symptom.

OBJECTIVES

This review article gives an overview of the state of research regarding psychological and psychoneuroimmunological factors and the resulting therapeutic options.

MATERIALS AND METHODS

The article is based on a literature search in the PubMed database.

RESULTS

Under experimental conditions, pruritus can be induced by verbal instructions and modulated by placebo and nocebo effects. Stressful life events can also induce pruritus or its exacerbation. This can also be demonstrated on a cellular level.

CONCLUSION

The knowledge that pruritus intensity is modulated by cognitions, behavioral factors, and stress is important for the development and application of psychological interventions. More research should be done regarding psychological interventions in the treatment of chronic itch and they should be applied clinically more often.