Abnormal diurnal patterns of salivary α-amylase and cortisol secretion in acute patients with anorexia nervosa

Objectives. The evidence that the activity of the sympathetic nervous system (SNS) is decreased in acute anorexia nervosa (AN) is not consistent. Therefore, we aimed to assess the SNS basal activity in malnourished AN patients through the measurement of diurnal salivary levels of alpha-amylase, whose secretion is regulated by the SNS. As secondary aim, we measured also salivary cortisol. Methods. Eight symptomatic female patients with restrictive AN and eight age-matched healthy women underwent saliva sample collection at awakening and over the day. alpha-amylase and cortisol were assayed by ELISA method. Results. In both patients and controls, saliva alpha-amylase levels significantly decreased during 60 min after awakening and then progressively rose towards the afternoon/evening. AN patients exhibited significantly reduced levels of the salivary enzyme with a significant decrease in its overall diurnal secretion and a dysregulated secretory pattern. As compared to control women, AN patients exhibited significantly enhanced levels of salivary cortisol at awakening, an enhanced and advanced cortisol secretion after awakening but no significant change in the overall diurnal secretion of the salivary hormone. Conclusions. These results suggest that the activity of the SNS, evaluated through the assessment of the diurnal secretion of salivary alpha-amylase, is impaired in the acute phase of AN whereas the cortisol awakening response is enhanced.