Stress and life expectancy
Chronic stress shortens life by a quarter – at least in baboons
Baboons – primates from the monkey family – are now considered as one of the "animal models" of human aging. And recently, American scientists have found out how the stress level, determined by the level of adrenal hormones, affects the life expectancy of these animals.
Article by Campos et al. Glucocorticoid exposure predicts survival in female baboons is published in the journal Science Advances.
The life of female primates such as baboons is extremely complicated. There is a place for a lack of food and water, a threat from parasites and predators, but they still have to raise children and take care of their social status!
It is not surprising that all this leads to the development of stress – scientists use this word to denote a non-specific reaction of the body to a variety of unfavorable external conditions. In vertebrates, this reaction primarily involves activation of the hypothalamus-pituitary-adrenal system. And the high level of steroid hormones glucocorticoids secreted by the adrenal cortex is widely used as a stress marker.
According to the "hypothesis of chronic stress", the chronic activation of the hypothalamus-pituitary-adrenal axis in response to too frequent or prolonged exposure to stress factors leads to a violation of hormonal regulation, deterioration of health and a decrease in life expectancy. This assumption is supported by the results of experiments on laboratory animals.
There is evidence that in humans, the constant effect of adverse circumstances, including social isolation and low socio-economic status, is associated with increased secretion of glucocorticoids. And their chronic increase, in turn, leads to the development of cardiovascular diseases, type 2 diabetes mellitus and immune disorders.
Nevertheless, laboratory animal models of chronic psychosocial stress may not be completely adequate in relation to humans, and in ongoing human studies it has not yet been possible to identify a direct link between an increase in glucocorticoid levels against the background of social adversity and life expectancy. Thus, the question of the influence of individual differences in the stress response on the life expectancy of humans or animals in natural conditions remains open.
The answer to this question is given by a study within the framework of the project for the study of yellow baboons Papio cynocephalus from Amboseli National Park in Kenya, which has been conducted since 1971. For more than 20 years, scientists have taken almost daily samples of female feces, in which the level of glucocorticoids was measured, and also collected related environmental, demographic and behavioral data. In this way, the researchers avoided contact with animals and their additional stress. A total of 242 females were involved in the work.
It turned out that females with chronically high levels of glucocorticoids, as a rule, died at a younger age. According to the constructed model, a female who had a very high level of glucocorticoids during her lifetime should die about 5.5 years earlier than a female with a very low one. And this is neither more nor less, but more than a quarter of the monkey's life, which is an average of 19 years. At the same time, the cause of such hormonal differences are both the stressors themselves and an excessive individual reaction to them.
In any case, adaptation, which initially developed as a saving one, can steadily provoke excessive secretion of glucocorticoids during life in society. And this may well shorten the life not only of the baboon, but also of you and me.
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