The biology of burnout: Causes and consequences.

Objectives: Burnout is a state of exhaustion resulting from prolonged and excessive workplace stress. We sought to examine biological underpinnings of burnout, focussing on mechanisms and physical consequences.
Methods: We searched the literature on burnout and evaluated studies examining biological parameters in patient populations (i.e. 'clinical' burnout) as well as in individuals from the general population judged as having some degree of burnout evaluated using a dimensional approach.
Results: Findings suggest that burnout is associated with sustained activation of the autonomic nervous system and dysfunction of the sympathetic adrenal medullary axis, with alterations in cortisol levels. Limited studies have also shown altered immune function and changes in other endocrine systems. Consequences of burnout include increased allostatic load, structural and functional brain changes, excito-toxicity, systemic inflammation, immunosuppression, metabolic syndrome, cardiovascular disease and premature death. Limitations of studies include variability in study populations, low specificity of burnout measures, and mostly cross-sectional studies precluding examination of changes across the course of burnout.
Conclusions: Further examination of biological mechanisms of burnout would benefit from more homogeneous clinical samples, challenge tests and prospective studies. This would assist in differentiation from conditions such as depression and aid with development of specific treatment targets for burnout.