Background & Aims

Chronic itch is a symptom of several pathological conditions and affects almost 20% of the population, interfering with vital functions. The biomedical model of itch focuses on the biological processes of the phenomenon but cannot fully account for the perception of itch; for this reason, a biopsychosocial model has been developed and it postulates that personality characteristics and cognitive factors are involved in itch perception 1. Studies have been conducted to investigate the relation between itch and psychological factors on patients with different forms of skin conditions. It has been found that helplessness 2, worrying 3, depression 4, anxiety 5, and stress 6 are associated with itch intensity.
Since it has been speculated that all these aspects are a consequence of chronic itch conditions, rather than a cause 1, this study aims to investigate if different psychological factors affect itch perception in healthy volunteers during histaminergic and non-histaminergic itch model

Methods

18 healthy subjects were recruited for this study. The experiment was conducted in 2 sessions 3 days apart. During the first session, participants were asked to fill out the following questionnaires: Reinforcement Sensitivity Theory – Personality Questionnaire (RST-PQ), Pittsburg Sleep Quality Index (PSQI), Depression, Anxiety, Stress Scale (DASS-21). After that, cowhage (non-histaminergic itch model) was applied on one forearm and subjects rated itch and pain intensity for 9 minutes using an eVAS. After the removal, subjects filled in the Learned Helplessness Scale (LHS). During the second session, only DASS-21 was administered before the application of histamine (histaminergic itch model) on the other forearm. After 9 minutes of itch and pain intensity rating on the eVAS, LHS was filled in by the subjects. The order of histamine and cowhage was randomized between the two sessions. Peak itch/pain intensity and AUC (area under the curve) of itch/pain were extracted from VAS recording.

Results

Cowhage itch: Results from linear regression analyses showed that stress (?=0.58 p=0.011) and anxiety (?=0.47 p=0.049) predict peak itch intensity. Correlation analyses showed that higher peak itch intensity was associated with higher stress and anxiety scores (p<0.05). Cowhage pain: Anxiety (peak ?=0.50 p=0.034; AUC ?=0.47 p=0.05), depression (AUC: ?=0.50 p=0.033) and sleep disturbance (peak ?=0.52 p=0.026; AUC ?=0.48 p=0.045) predict pain from linear regression analyses. Higher pain intensity was correlated with higher anxiety (peak p<0.05; AUC p<0.05), depression (AUC p<0.05), and sleep disturbance (peak p<0.05; AUC p<0.05) scores. Histamine itch: From linear regression analyses histaminergic itch is predicted by tendency to fear (FFFS; peak ?=0.54 p=0.021; AUC ?=0.47 p=0.046), stress (peak ?=0.51 p=0.032), and helplessness (peak ?=0.51 p=0.029). Higher itch intensity is correlated with higher FFFS (peak p<0.05; AUC p<0.05), stress (peak p<0.05) and helplessness (peak p<0.05) scores.

Conclusions

Anxiety, depression, and sleep disturbance showed an increased modulatory effect on itch and pain intensity induced by cowhage, but not on histaminergic itch. Stress levels are associated with both histaminergic and non-histaminergic itch, while tendency to fear and helplessness are associated only to itch intensity induced by histamine.
These preliminary data indicate that psychological factors are not only a consequence of chronic itch, but they can also influence the itch and pain perception. This study is not complete and data collection is still ongoing.

References

1.Verhoeven EWM, Klerk S de, Kraaimaat FW, Van de Kerkhof PCM, De Jong EMGJ, Evers AWM. Biopsychosocial mechanisms of chronic itch in patients with skin diseases: a review. Published online 2008.
2.Evers AWM, Lu Y, Duller P, Van Der Valk PGM, Kraaimaat FW, Van De Kerkhof PCM. Common burden of chronic skin diseases? Contributors to psychological distress in adults with psoriasis and atopic dermatitis. British Journal of Dermatology. 2005;152(6):1275-1281.
3.Fortune DG, Richards HL, Main CJ, Griffiths CEM. Pathological worrying, illness perceptions and disease severity in patients with psoriasis. Br J Health Psychol. 2000;5(1):71-82.
4.Gupta MA, Gupta AK, Kirkby S, et al. Pruritus in psoriasis: a prospective study of some psychiatric and dermatologic correlates. Arch Dermatol. 1988;124(7):1052-1057.
5.Evers AWM, Duller P, Van De Kerkhof PCM, et al. The Impact of Chronic Skin Disease on Daily Life (ISDL): a generic and dermatology?specific health instrument. British Journal of Dermatology. 2008;158(1):101-108.
6.Dalgard F, Svensson Å, Sundby J, Dalgard OS. Self?reported skin morbidity and mental health. A population survey among adults in a Norwegian city. British Journal of Dermatology. 2005;153(1):145-149.

Presenting Author

Giulia Erica Aliotta

Poster Authors

Giulia Erica Aliotta

PhD

Aalborg University

Lead Author

E-mail

Awaz Ahmad

Lead Author

E-mail

Emma Gynther Larsen

Lead Author

E-mail

Julie Rønnov Nielsen

Lead Author

E-mail

Silvia Lo Vecchio

Aalborg University

Lead Author

E-mail

Jesper Elberling

Lead Author

E-mail

Lars Arendt-Nielsen

PhD

Aalborg University

Lead Author

E-mail

Laura Petrini

Aalborg University

Lead Author

E-mail

Topics

  • Mechanisms: Psychosocial and Biopsychosocial