Increased vagal modulation in atopic dermatitis

Summary

Background

Atopic dermatitis has been shown to be associated with neurogenic and psychosocial factors. In related atopic diseases such as rhinitis or asthma, a shift in autonomic balance towards a parasympathetic modulation has been described. On the other hand, the psychiatric symptoms known for atopic dermatitis are often associated with decreased vagal modulation. Furthermore, an increased parasympathetic activity has been shown to exhibit anti-inflammatory effects, thus rather alleviating dermatitis symptoms.

Objective

In order to address these intriguing discrepancies, we aimed to assess the autonomic state in patients suffering from atopic dermatitis.

Methods

Heart rate variability assessment was performed in 30 patients and data were compared to those obtained from matched controls. Furthermore, questionnaires for disease activity and psychosocial stressors were employed.

Results

Patients showed higher values for parasympathetic modulation than controls. This was mainly reflected by an increase in the root mean square of successive differences (RMSSD). This parameter further correlated with dermatological symptoms and the time since the last severe exacerbation of the disease. In addition, subgroups of patients with dyshidrosis or photophobia showed significant differences in autonomic modulation under deep respiration. Moreover, cardiac autonomic modulation was hardly altered upon postural change, indicating that autonomic reactivity is only mildly influenced in these patients.

Conclusion

Patients with atopic dermatitis showed an autonomic dysbalance which is comparable to other diseases related to atopy or allergy. Our findings point to the question whether these alterations are disease-inherent or counter-regulatory, which should be addressed in future studies.

Introduction

Neurogenic and psychoemotional factors have been recognized to exacerbate symptoms and to trigger episodes in diseases belonging to the field of atopy and allergy [1]. One of these diseases that are characterized by chronic relapse and significant discomfort is atopic dermatitis. Dermatitis severity is associated with stress perception, anxiety or depression [2], [3], [4], [5]. In recent years, several pathways via which stress might influence atopic or allergic disease have been identified [6]. First, an abnormal activation of the hypothalamic-pituitary-adrenocortical axis might account for neuro-immune interaction [1], [7], [8]. Second, stress-induced local inflammation can be caused by nerve fiber–mast cell interactions, possibly mediated by neuropeptides such as substance P (SP) [9], and third, increased sympathetic activity has been described [1]. The latter might directly or indirectly affect the inflammatory response with increased numbers of eosinophils, increased levels of IgE and interferon-γ, or decreased concentrations of the anti-inflammatory cytokine interleukin-4 [10]. However, an autonomic dysbalance leading to changes in vagal modulation might play an important role, since anti-inflammatory effects have been described for efferent vagal activity [11], [12].

To date, the cardiac autonomic system has not been examined in atopic dermatitis in detail. In distantly related diseases such as bronchial asthma or allergic rhinitis, however, autonomic alterations have been reported, predominately showing parasympathetic predominance [13], [14].

Interestingly, in the psychiatric diseases that are associated with atopic dermatitis, i.e. depression or anxiety, an autonomic dysbalance with decreased parasympathetic modulation has been described. For instance, both short and long-term complexity measures of heart rate modulation indicating parasympathetic activity have been shown to be reduced in major depression [15], [16] or during treatment [17]. Furthermore, a relative decrease of vagal activity has repeatedly been described for anxiety [18], [19].

Here, we tested the hypothesis that an autonomic dysbalance can be determined for patients suffering from atopic dermatitis by means of heart rate variability (HRV) measures. Furthermore, we aimed to assess whether autonomic alterations mirror those seen in other atopic diseases or those known for the described psychiatric symptoms, i.e. increased or decreased parasympathetic modulation, respectively. For this purpose, we investigated 30 dermatitis patients and 30 controls matched with respect to age, gender and smoking behaviour. In addition to the electrophysiological recordings, scores for disease activity and psychosocial stressors were obtained and correlated with cardiac autonomic parameters.