Salivary alpha-amylase, secretory IgA and free cortisol as neurobiological components of the stress response in the acute phase of anorexia nervosa

Abstract

Objectives One novel hypothesis of the pathogenesis of anorexia nervosa (AN) is the possible role of mental stress in hyperactivity of the autonomic nervous system (ANS) and of the hypothalamic–pituitary–adrenal (HPA) axis. Two components of stress response – salivary alpha-amylase (sAA) and free cortisol – have been proposed. They can be determined in saliva, which closely reflects their concentrations in plasma. The purpose of this study was to measure salivary free cortisol, sAA and their correlation to secretory IgA (sIgA) of patients with AN in comparison to the average population. Methods A controlled clinical trial was designed for a matched group of 47 AN patients and 54 healthy individuals. After clinical examination, unstimulated salivary samples were taken during the acute stage of AN (BMI < 15 kg/m²) in the first week of hospitalisation. An enzyme-linked immunosorbent assay (ELISA) suitable for measuring sAA, sIgA and free cortisol were used. Results Anorexic patients exhibited disturbances in sAA secretion, and significantly increased cortisol and sIgA levels with a distinct correlation between these two parameters. Conclusions The behaviour of cortisol, sAA and sIgA levels can be assessed as an effect of stress reaction among AN patients with hyperactivity of the HPA axis and ANS dysregulation. The effect of stress response can be assessed reliably in saliva.

Keywords:

• Anorexia nervosa
• cortisol
• saliva
• alpha-amylase
• sIgA

Acknowledgements

The authors would like to thank all those who participated in this study for their enthusiastic involvement and hard work. We would like to thank Mrs Ewa Banach for her work in the laboratory and gratefully acknowledge the assistance of Prof. Geoffrey Shaw for his helpful guidance and advice concerning English language editing. The authors would like to thank the Poznan University of Medical Sciences for supporting the study. The funders had no role in study design, data collection and analysis, the decision to publish, or the preparation of this manuscript.

Statement of interest

None to declare.