FormalPara Key Summary Points

Chronic pruritus is defined as pruritus lasting for at least 6 weeks and can be idiopathic, psychogenic, neuropathic or, more frequently, linked with primary dermatoses or systemic disorders

Itch is processed by two main neuronal pathways: acute itch involves the histaminergic pathway, while chronic itch is processed by the nonhistaminergic pathway

The mechanisms which explain chronic pruritus include the concepts of peripheral and central sensitization

Mast cells have a key role in the understanding of the link between distress and pruritus through the activation of the central and the peripheral hypothalamic-pituitary-adrenal axes, with relevance in psychodermatological diseases

The experience of chronic pruritus can be modulated by psychological factors and can be associated with psychiatric comorbidities and significant impact on quality of life, which should be addressed in clinical practice

Introduction

Pruritus is the most common cutaneous symptom and is defined as an unpleasant sensation that causes a desire to scratch [7]. Pruritus can also be a marker of drug response [8]. Pruritus has complex etiopathogenesis that can involve histaminergic and non-histaminergic pathways [39, 40].

Finally, another relevant psychological feature of pruritus is its modulation by verbal suggestion. For example, increased intensity of pruritus was observed upon catastrophizing instructions. In another study, when patients with AD believed they had a pruritus-inducing solution on the skin, they experienced an increase in the severity of pruritus. This study also showed that this clinical finding was associated with brain activity changes. Thus, the expectations influence how mental pruritus stimuli are actually experienced, a finding that may have therapeutic relevance [15, 41].

Pruritus as a Cause of Psychological Distress and Psychopathology

Many studies have demonstrated the significant negative impact that CP has on the quality of life (QoL), including but not limited to anxiety, sleep disturbances, depression and sexual dysfunction [10, 42]. This negative impact on patients' QoL has highlighted the importance of examining the relationship between CP and secondary psychiatric disorders. The following section will explore the multifaceted connection between CP and psychiatric comorbidities, with a focus on common specific skin disorders, namely, AD, psoriasis and acne. This perspective will additionally highlight the potential benefits of psychotherapeutic interventions in the treatment of CP, thereby lessening the burden of disease in these patients.

In AD, individuals not only face the social burden of visible disease but also the debilitating effects of CP, contributing to the increased prevalence of anxiety and depression induced by the discomfort of CP [43].

Psoriasis has also been reported to produce severe CP in > 70% of patients [11]. For many patients, the distress caused by CP extends beyond physical discomfort to significant social implications, including embarrassment from visible skin flaking and blood-stained clothes, contributing to the development of anxiety and depression. This distress is not only prevalent for patients themselves but extends to impact the lives of those whom they live with. Moreover, sexual function and desire were also demonstrated to be negatively impacted by the consequences of itchiness, further highlighting the profound effect on overall well-being in patients with CP. Irrespective of this demonstrated profound effect on the QoL, a study by Taliercio et al. revealed that the severity of itching is not always strongly correlated with disease progression or severity [44]. As a result, despite the prevalence of itch in patients with psoriasis, patients may feel that their itchiness is not adequately addressed by physicians, who primarily focus on assessing the severity of psoriatic lesions during their clinic visits. Moreover, many patients struggle to find a cure for their CP, resorting to inappropriate methods such as using extreme water temperatures to drown out their need to itch. Thus, an emphasis on exploring pruritus severity and exploring alleviating treatment options should be made during clinic visits to lessen the burden of disease and provide resources and safe treatment options for patients with psoriasis experiencing CP.

According to the American Academy of Dermatology, acne is the most commonly experienced skin condition in the US [45]. Despite acne affecting a large proportion of the adolescent and adult population, few studies have assessed the psychological burden of itching in patients with acne. In a study aimed to investigate the prevalence, intensity and psychological burden of acne in patients, Szepietowska et al. [46] demonstrated that acne itching, regardless of acne severity, was shown to have a significant negative impact on patient QoL. In that study, the authors highlighted that similar to patients with psoriasis, patients with acne also regard itching as one of the most debilitating symptoms of their skin condition, contributing to the increased risk of anxiety and depression among patients with these diseases.

Although the prevalence of CP in various inflammatory skin conditions has been well documented in the literature, there is limited discussion regarding psychological management for CP. However, clinical evidence has demonstrated that interventions aimed at reducing distress levels in patients have proven effective in breaking the distress-itch cycle. These interventions include habit reversal training (HRT), relaxation therapy, cognitive behavioral therapy (CBT), contextual cognitive behavioral therapy (CCBT), meditation and hypnosis [47, 48]. In addition to non-pharmacological interventions, psychotropic treatment should be considered. This can include antidepressants, antipsychotics and anticonvulsants, which have been reported to simultaneously alleviate the urge to itch, depending on the associated psychopathology, to address psychological consequences, such as anxiety and depression [49].

Pruritus is one of the main determinants of QoL in dermatological disease [50]. A brief mental state examination can be performed in clinical practice to identify the most important aspects of mental health linked with the psychodermatological disorder associated with CP [51]. Useful questionnaires and scales are available to assess mental health, co** and QoL in psychodermatology, as illustrated in Fig. 2 [52,53,54,55,56,57,58,59,60,61,62]. They can be used as an adjunct to the clinical interview. Although a psychodermatological assessment should ideally be carried out in the context of a specific psychodermatology consultation, with the simultaneous participation of a dermatologist and a mental health specialist (psychologist or psychiatrist), there are some common and key psychosocial issues that should be part of the general dermatological approach, namely, the general assessment of symptoms of anxiety and depression and the impact of skin disorders on QoL.

Fig. 2
figure 2

Examples of specific questionnaires and scales to assess mental health, co** and quality of life in psychodermatology

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Conclusion

Pruritus is multifactorial, and psychological distress can contribute as a trigger for certain chronic dermatoses that are associated with CP, such as AD or psoriasis, leading to an increase in the severity of pruritus as well. In addition, CP associated with chronic dermatoses and systemic diseases is associated with a higher prevalence of secondary psychopathological symptoms such as depressive symptoms, with a significant impact on the QoL of these patients. Moreover, some personality characteristics, such as alexithymia, can impact the co** strategies used by these patients.

Therefore, the overall management of patients with CP must consider the weight of underlying psychological and psychiatric aspects. Although it is still an underdiagnosed, undervalued and undertreated topic in general clinical practice in dermatology, addressing psychopathology, the patient’s psychosocial context and the importance of certain personality traits (such as alexithymia) is also the mainstay of the treatment, along with specific therapeutic approach of the underlying dermatosis or systemic disorder, if present. A psychodermatological approach to CP could have an impact on decreasing the severity of pruritus and improving the patient’s QoL, by reducing psychological distress as a potential trigger (in several chronic dermatoses), exploring psychosocial factors closely linked with CP (particularly, in psychogenic pruritus) and improving co** strategies used by these patients to deal with the underlying etiology and the burden of having CP.