The Adverse Effects of Stress

    People experience stress in many different situations. Things like the pandemic, work, school and family life can all induce stress in human beings. The internal changes that the body goes through during stress can cause many adverse effects in a person’s life. It can lead to a number of mental illnesses and it can even change human behavior. One of the possible effects of stress is weight gain as a result of the hypothalamic-pituitary-adrenal axis response. Many people turn to stress eating, or overeating, in order to cope with their emotions.  

    Researchers Anna Weinberg, et. al., investigated the neural responses that people have to reward under acute stress in their study, “Risk and Resilience in an Acute Stress Paradigm: Evidence From Salivary Cortisol and Time-Frequency Analysis of the Reward Positivity.” They studied one hundred male individuals and divided them into a control group and a stress group. They chose to study males because menstrual phases and hormonal changes in women have been found to, “significantly influence physiological responses to stress” (Weinberg, et. al., 12). Both groups were to complete a Doors task, a Flanker task and MIST on a computer while EEG and salivary cortisol levels were recorded. A supervisor was used to increase stress in the stress condition. They found that the participants in the stress condition displayed higher cortisol levels than those in the control group. Over time, the cortisol levels of the control group decreased while the cortisol levels of the stress group increased. The higher levels of cortisol are released by the hypothalamic-pituitary-adrenal axis (HPA axis) in response to acute stress (Weinberg, et. al., 2). In addition, EEG recordings showed the association between neural responses and the reward processing system. The stress condition displayed a reduction in neural responses in the second Doors task. It’s important to note that, “neural responses to gains and losses were blunted after the stressor” (Weinberg, et. al., 11). Overall, this study provides evidence for increased levels of cortisol and blunted neural responses in the reward processing system in acute stress conditions. 

    In addition to desensitizing the neural responses to gains and losses, the HPA axis response to stress also causes adverse effects in relation to eating. The article, “Stress, cortisol, and other appetite-related hormones: Prospective prediction of 6-month changes in food cravings and weight” by Ariana M. Chao, et. al., discusses the specific effects of stress on eating and weight gain. In this study, three hundred and thirty nine adults completed baseline assessments and a follow up after six months. It is known that the increase in cortisol from the HPA axis response leads to a greater intake of calories and highly palatable foods. Thus, the researchers measured the levels of chronic stress, food cravings and insulin resistance in participants for their baseline assessment. After six months they found that, “increased cortisol and self-reported stress [promotes] weight gain” (Chao, et. al., 7). This is due to the effects of cortisol on insulin resistance. Specifically, the stimulation of gluconeogenesis from high cortisol levels causes a resistance to insulin in the body. The increase of cortisol from stress also modulates, “brain extrahypothalamic reward and motivation regions to influence future weight gain” (Chao, et. al., 8). This ties in with another study that demonstrates the relationship between the reward processing system and stress eating. Highly palatable food can activate the reward system and promote dependence much like drugs do. Specifically, palatable food can create opioid dependence which produces behavioral reinforcement. Since the release of opioids in the body stems from the activation of the HPA axis, it increases the intake of palatable food and in turn, palatable food sustains opioid release (Adam, et. al., 455). This is what causes stress eating to become addictive when trying to cope with chronic stress. 

    These studies display different ways the body responds to stress in relation to the HPA axis, neural responses and the reward processing system. As shown in Dr. Weinberg’s study, acute stress causes desensitized neural responses to rewards. In addition, the HPA axis releases high levels of cortisol in the body. The high cortisol levels can directly cause a need for more calorie dense foods and highly palatable foods. This increase in intake can then result in dependence, weight gain and many other adverse effects. Stress is a common problem in society and can be induced in many situations. Thus, it’s important to find healthy coping mechanisms in order to reduce and prevent the negative effects of stress on the body. 

Citations:

Adam, Tanja C, and Elissa S Epel. “Stress, eating and the reward system.” Physiology & behavior vol. 91,4 (2007): 449-58. doi:10.1016/j.physbeh.2007.04.011

Chao, Ariana M et al. “Stress, cortisol, and other appetite-related hormones: Prospective prediction of 6-month changes in food cravings and weight.” Obesity (Silver Spring, Md.) vol. 25,4 (2017): 713-720. doi:10.1002/oby.21790

Ethridge, P., Ali, N., Racine, S. E., Pruessner, J. C., & Weinberg, A. (2020). Risk and Resilience in an Acute Stress Paradigm: Evidence From Salivary Cortisol and Time-Frequency Analysis of the Reward Positivity. Clinical Psychological Science, 8(5), 872–889. https://doi.org/10.1177/2167702620917463