Chapter 22: Psychodermatology

INTRODUCTION

Psychodermatology is a field that encompasses disorders in which both the psyche of the patient and the dermatological aspects are essential components. It has been reported that 30% to 40% of patients seeking treatment for skin disorders have an underlying psychiatric or psychological component that either causes or exacerbates their skin problem.

PATHOPHYSIOLOGY–THE ENDOCRINE-NEURO-IMMUNO-CUTANEOUS MODEL

The brain, nervous system, and skin are all embryologically derived from the neuroectoderm. These organs are linked by a complex network of hormones, neuropeptides, cytokines, and other effector molecules. For example, psychological stress results in the release of stress hormones (such as corticotrophin-releasing hormone, adrenocorticotropin-releasing hormone, cortisol, and prolactin) from the hypothalamic pituitary axis. Sympathetic nervous system activation leads to the release of neuropeptides (substance P and calcitonin gene-related peptide). Mast cells in the skin are important targets of these stress hormones/mediators, and their activation leads to immune dysregulation and contributes to the pathogenesis of the skin disease.

Epigenetics is another likely explanation for the interplay of disease states between mind and skin. Psychological factors can lead to altered regulation of gene expression via various molecular mechanisms (DNA methylation, histone modification, and micro-RNA dysregulation) and eventually result in various skin diseases.

Classification

Psychodermatological disorders can be broadly classified into three categories:

1. Psycho-physiological disorders

2. Secondary psychiatric disorders

3. Primary psychiatric disorders

Psycho-physiological Disorders

Psycho-physiological disorders are skin diseases which are affected by the psychological state of the patient. These diseases are often triggered or exacerbated by emotional stress, anxiety, and/or depression. Typical diseases in this group include acne vulgaris, atopic dermatitis, psoriasis, chronic urticaria, herpes simplex infection, hyperhidrosis, and telogen effluvium. Generally, patients have an insight into their diseases but are unable to manage the psychological factors aggravating their skin disease.

Secondary Psychiatric Disorders

In secondary psychiatric disorders, psychiatric conditions arise as a result of skin diseases. Skin diseases, especially those which are chronic, affecting exposed parts of the body, and are cosmetically unappealing, often lead to embarrassment, poor self-image, and low self-esteem. These may in turn, result in anxiety, depression, and suicidal ideation.

PRIMARY PSYCHIATRIC DISORDERS

In primary psychiatric disorders, the primary pathology is in the psyche, and skin complaints are self-induced and secondary. The main diseases in this group are delineated in Table 22.1. There is often an underlying psychiatric problem, such as delusion, anxiety, depression, obsessive-compulsive disorder, impulse-control disorder, and personality disorder.