Are patients with chronic pruritus more susceptible to social stress than healthy controls? An experimental case-control study

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.

Effects of Stress on Itch

PURPOSE

Psychological stress and ensuing modulation of the immune and nervous systems can have a significant impact on itch. Stress can exacerbate itch and vice versa, resulting in a vicious cycle that can greatly impair a patient's quality of life. This review summarizes the association between stress and itch, elucidates the mechanism by which these two phenomena influence one another, and explores treatment modalities that aim to reduce stress-induced itch.

METHODS

A complete search of the PubMed and Google Scholar databases was completed and literature pertinent to this review was compiled.

FINDINGS

Both acute and chronic stress can significantly affect itch in healthy individuals and in those diagnosed with itchy skin diseases as well as systemic diseases, thus resulting in a vicious cycle in which stress exacerbates itch and vice versa. The mechanisms by which stress induces or aggravates itch include both central and peripheral activation of the hypothalamic-pituitary-adrenal axis and sympathetic nervous system. Activation of these systems, in turn, affects the mast cells, keratinocytes, and nerves that secrete neuropeptides, such as substance P, nerve growth factor, acetylcholine, histamine, and itchy cytokines. A dysfunctional parasympathetic response is thought to be involved in the chronic stress/itch response. Brain structures associated with emotion, such as the limbic system and periaqueductal gray, which work on the descending facilitation of itch, play a significant role in stress-induced itch.

IMPLICATIONS

As specific brain structures are associated with stress, drug treatments targeting these areas (ie, γ-aminobutyric acid-ergic drugs, serotonin and norepinephrine reuptake inhibitors) may help to modulate itch. Stress can also be combatted using nonpharmacologic treatments such as cognitive-behavioral therapies and stress-relieving holistic approaches (eg, yoga, acupuncture).

Real-World, Non-Interventional, Observational Study of Hydroxyzine Hydrochloride in Chronic Pruritus: a Prospective, Non-Comparative Study

INTRODUCTION

Although hydroxyzine is widely used for symptom relief in pruritus, its clinical safety and efficacy data in the Indian setting are scarce. We conducted a study to assess the effectiveness and tolerability of hydroxyzine in the management of Indian patients with chronic pruritus in a real-world setting.

METHODS

This was a prospective, observational, patient-reported outcomes (PRO) study in patients with chronic pruritus due to dermatological causes treated with hydroxyzine as per the clinician's discretion for a period of up to 12 weeks. The primary outcome was improvement in quality of life from baseline, assessed using the 10-point Dermatology Quality of Life Index (DLQI) at week 12 of the study period. Secondary outcomes were improvement in the pruritus scores (5-D itch scale) at 12 weeks, improvements in the DLQI and 5-D itch scores at 2, 4 and 8 weeks and safety.

RESULTS

The study included 400 patients (179 males, 221 females) from 7 dermatology centres across India. Of the 400 patients recruited, 391 patients completed at least 2 weeks of treatment. There was significant (p < 0.0001) improvement from baseline in the DLQI scores and 5-D itch scores at 2, 4, 8 and 12 weeks; 189/391 (48.34%) patients had symptom relief leading to early termination. Overall, the treatment was well tolerated with a total of 11 mild-to-moderate adverse events reported during the study, which included dizziness, constipation, drowsiness, dry mouth and sedation. All events resolved without any intervention. There were no serious adverse events.

CONCLUSION

This real-world, observational, PRO study demonstrates that hydroxyzine significantly improves symptoms of pruritus and quality of life in patients with chronic pruritus due to dermatological causes over 12 weeks. Despite the sedating potential of the drug, hydroxyzine is well tolerated in real-world settings.

TRIAL REGISTRATION

CTRI/2017/06/008847.

FUNDING

Dr. Reddy's Laboratories.

Why does stress aggravate itch? A possible role of the amygdala

Stress is the exacerbating factor of itch across patients with chronic itch due to different origins. However, the precise mechanisms behind stress-induced exacerbation of itch remain unknown. Chronic stress induces hyperexcitability of the amygdala, the centre of emotional processing. Recent findings on the itch neuronal pathways support a pivotal role of the amygdala for itch processing. We hypothesized that itch is enhanced by stress through hyperexcitation of the amygdala. Modulation of amygdala activity, therefore, may have therapeutic potential in the treatment of chronic itch.