The study found that not only major stressful experiences such as bereavement but chronic challenges like financial strain were also detrimental to the healthy interaction of the immune, nervous, and endocrine systems. Communication between these systems is required to maintain optimal health, disruption is linked to a wide range of both mental and physical illnesses from depression and schizophrenia to cardiovascular diseases.
When threats such as stress occur, signals between these systems are activated and spur physiological and behavioral changes. This study analyzes blood concentrations of four biomarkers among 4,934 participants over the age of 50 years to investigate this process. Two of the biomarkers were proteins involved in the innate immune response to inflammation, and two were hormones involved in the physiology of the stress response (C-reactive protein and fibrinogen, and cortisol and IGF-1, respectively).
Three groups of participants were created and labeled as being low risk to health, moderate risk, and high risk after using a sophisticated statistical technique profile analysis to identify clusters of biomarker activity. Then the researchers investigated how earlier exposure to stressful situations may affect the likelihood of participants falling in the high-risk group.
According to the researchers, exposure to stressful circumstances overall, ranging from being an unpaid/informal caregiver to experiencing a bereavement or divorce in the last two years was linked to a shocking 61% increase in the likelihood of being in the high-risk group four years later. Looked at separately the effect was cumulative, with the likelihood of belonging to the high-risk group increased by 19% for each stressor experienced for those who experienced more than one stress-inducing situation. Finally, those who only reported experiencing financial strain (the perception that they may not have the financial resources required to meet their future needs), were found to be 59% more likely to belong to the high-risk group four years later.
“When the immune and neuroendocrine systems function well together, homeostasis is maintained and health is preserved. But chronic stress can disrupt this biological exchange and lead to disease,” said lead author, PhD candidate Odessa S. Hamilton (UCL Institute of Epidemiology & Health Care). “We found that financial stress was most detrimental to biological health, although more research is needed to establish this for certain. This may be because this form of stress can invade many aspects of our lives, leading to family conflict, social exclusion, and even hunger or homelessness.”
Additionally, further investigations looking at genetic variants found to influence the body’s immune-neuroendocrine responses revealed that the association between stressful circumstances and belonging to the high-risk group four years later remained true irrespective of genetic predisposition. Experiencing chronic stress over a long period of time can disturb/disrupt communication between the neuroendocrine and immune systems. This is because our body’s response to stress is very similar to the response to sickness in activating some of the same pathways, for example, both trigger the production of pro-inflammatory cytokines.
