Throughout our lives we are repeatedly exposed to different types of stress, from life events and experiences in our relationships, to school, work and home. Over time, adverse experiences and stress can add up, even to the point of having toxic consequences on our overall health and well-being. This buildup of adverse experiences and stress is known as cumulative adversity. Although humans have an innate ability to adapt and be resilient to stressful events and situations, chronic high stress and adversity can be extremely harmful to our physical and mental health.
High chronic stress is associated with problems such as:
- Damage to the branch-like extensions of cells (i.e., dendrites) in the medial prefrontal cortex (PFC), a brain region that is important for regulating emotions, decision-making, memory and stress
- Reduced gamma-aminobutyric acid (GABA)-stimulated chloride uptake in the amygdala, an area of the brain that plays an important role in emotional processing and fear responses and pleasure
- Altered structure of synapses (i.e., connection between two cells) in the hippocampus
- An increase in the number of receptors on the surface of target cells (upregulation) in the striatum, which is important for balance, pleasure, cognitive function and voluntary movements
Consequently, high cumulative stress can increase our risk for physical health problems, including neuroendocrine, inflammatory and cardiovascular problems, and mental health problems, including anxiety and depressive disorders.
Rajita Sinha, Ph.D., professor in the department of psychiatry at Yale University, and her colleagues, have conducted a number of studies on the consequences of stress on human behavior, brain function and structure. In a 2014 study, Sinha and colleagues examined the effects of cumulative adversity on a person’s sensitivity to stress and the risk of adverse health outcomes. The researchers compared the brain activity of 75 participants during stress and different levels of cumulative adversity, and their association with adverse health outcomes. The main findings of this study indicated that cumulative adversity significantly impacted the participants’ ability to respond to acute stress and contributed to increased adverse health symptoms.
Brain circuits that help people cope with stress
A recent study published in the journal Molecular Psychiatry examined the effects of chronic stress on mice and the ability of the brain to undergo structural plasticity within the amygdala in response to chronic stress. The researchers exposed mice to chronic stress for 21 days and then examined the changes that occurred in response to chronic stress in three areas of the amygdala.
Although one area showed no changes, the second area of the amygdala of the chronically stressed mice had longer and more complex dendrites. The researchers noted that these changes are similar to those in people with mental illnesses such as anxiety and depression. In addition, there was shrinkage of the dendrites that connected with other areas of the brain in the third area of the amygdala, which indicated that the mice would be less able to adapt to new experiences.
This study found that chronic stress can negatively affect the brain, impacting our ability to adapt to stress and new experiences and increasing our risk for mental health conditions such as anxiety and depressive disorders. The ability to undergo structural plasticity to provide greater resilience to stress allows the adult brain to adapt effectively to internal and external stress.
Unfortunately, this means that when structural plasticity fails, the normal structure and function of the brain are not preserved and resilience does not occur. As a result, chronic stress can increase the development of anxiety and depressive disorders.
Sovereign Health of California provides evidence-based, individualized behavioral health treatment services to patients with mental illness, substance use disorders and co-occurring disorders. To find out more about our treatment programs at Sovereign Health, please contact our 24/7 helpline to speak to a member of our team.
About the author
Amanda Habermann is a writer for Sovereign Health. A graduate of California Lutheran University, she received her M.S. in clinical psychology with an emphasis in psychiatric rehabilitation. She brings to the team her background in research, testing and assessment, and recovery techniques. For more information and other inquiries about this article, contact the author at firstname.lastname@example.org.