Does autonomic dysfunction play a role in atopic dermatitis?

Abstract

Atopic dermatitis (AD) is a chronic dermatitis characterized by intense itching and excessive skin dryness. The factor most commonly blamed for the pathogenesis of skin dryness in the disease is impaired barrier function of the stratum corneum. However, there are findings indicating that the autonomic nervous system, and the sympathetic nervous system in particular, is affected negatively in AD, and thus, autonomic dysfunction can be an important factor leading to skin dryness. In this study we aimed to evaluate the functioning of the autonomic nervous system electrophysiologically using R-R interval variation (RRIV) and the sympathetic skin response (SSR) in patients with AD, and to examine whether there is an underlying autonomic nervous system dysfunction. The study registered a total of 38 (12 males and 26 females) patients with AD, of whom 24 had active and 14 inactive disease, and 20 (10 males and 10 females) healthy control subjects. RRIV was used in our study as the electrophysiological test to evaluate the parasympathetic system. The SSR method, which is a noninvasive electrophysiological test with a significant role in evaluating the sudomotor activity of skin, as well as that of the unmyelinated fibres that take a part in this activity, was employed to assess the sympathetic nervous system. Our study revealed a significantly prolonged SSR latency and amplitude of the upper extremity in the patient group, relative to the control group (P < 0.05). When the group with active skin lesions was compared with the control group, the former was found to have prolonged SSR latency and amplitude in the upper extremity. The prolongation in SSR latency of the upper extremity was statistically significant (P < 0.05), while the prolongation in amplitude was not (P = 0.5). An evaluation of RRIV results did not show a significant difference between the patient and control groups. These findings demonstrate that the sudomotor activity controlled by the sympathetic nervous system, as well as unmyelinated fibres that play a role in this activity are affected in patients with AD. We think that the involvement of sudomotor activity may be one of the causes that leads to dysfunction in sweat glands and skin dryness.