Allostasis and Disease Biomarkers
Allostasis (AL) and Allostatic Overload (AOL) are states in which the system enters a dysregulated stress response. Non-communicable diseases have been shown to be associated with AL. For instance, the following disorders are linked to AOL:
Cardiovascular diseases, such as coronary or ischemic heart disease and peripheral arterial disease
Type II diabetes
Muscoloskeletal disorders, such as chronic fatigue syndrome and fibromyalgia
Cancers, such as breast and ovarian cancer
Depression, anxiety and PTSD
Non-communicable diseases are diagnosed using either physiological biomarkers (eg. glucose levels, blood pressure etc) of the stress response or through clinical assessment questionnaires that are aimed at quantitatively estimating levels of psychosocial stress. The latter offers a more personalised assessment of an individual’s experience of stress and their resilience, and how these affect risk of developing disease.
It is in this framework that the allostatic load index has been developed. It includes ten different biological parameters ranging from physiological to hormonal parameters, such as body mass index and cholesterol levels, that help in assessing the level of chronic stress of an individual. The parameters included in the allostatic load index are divided into three scales: primary, secondary and tertiary. Primary parameters are physiological ones that modulate the basic stress response; secondary are the ones that develop as a cumulative effect of the primary biomarkers; tertiary are the disease biomarkers resulting from a chronic presence of secondary parameters.
Overall, the allostatic load index seems to predict mortality and physical decline better than traditional methods using individual biomarkers of disease. Although advances in our understanding of AL and the development of the allostatic load index have improved our prediction of disease risks, some issues still persist. Indeed, western medicine is founded on the principle of curing or alleviating symptoms of disease rather than aiming to prevent their onset.
Future studies on AL and AOL should design methods to help early diagnosis and prevention of non-communicable diseases. The nature of AL and AOL, particularly their ability to permanently modify the baseline physiological parameters (HM) of an individual, raises questions regarding the mechanisms behind developmental disorders such as autism.
If dysregulated stress response biomarkers were demonstrated to be transmitted from parent to offspring, this would shed new light on the origins of complex developmental disorders.
Resources
McEwen, B., Nasveld, P., Palmer, M. & Anderson, R. Allostatic Load A Review of the Literature. (2012).
McEwen, B. S. Biomarkers for assessing population and individual health and disease related to stress and adaptation. Metabolism 64, S2–S10 (2015).
Guidi, J., Lucente, M., Sonino, N. & Fava, G. A. Allostatic Load and Its Impact on Health: A Systematic Review. Psychother. Psychosom. 1–17 (2020).
Fava, G. A. et al. Clinical characterization of allostatic overload. Psychoneuroendocrinology 108, 94–101 (2019).
Seeman, T. E., Singer, B. H., Rowe, J. W., Horwitz, R. I. & McEwen, B. S. Price of Adaptation—Allostatic Load and Its Health Consequences: MacArthur Studies of Successful Aging. Arch. Intern. Med. 157, 2259–2268 (1997).