Everyone needs some stress in their lives to function. However, long term stress can have long-term detrimental effects.

Chronic Stress and Chronic Disease

Stress has been linked to inflammation and chronic disease.  A recent study conducted by Carnegie Mellon University found that prolonged stress can lead to a wide range of diseases.  They tested the impact of chronic stress on the glucocorticoid receptor resistance. The glucocorticoid receptor functions in almost every cell in the body and controls the immune response. The study found that chronic stress resulted in glucocorticoid receptor’s failure to down-regulate the inflammatory response. The study concluded:

“These data provide support for a model suggesting that prolonged stressors result in (glucocorticoid receptor resistance) GCR, which, in turn, interferes with appropriate regulation of inflammation. Because inflammation plays an important role in the onset and progression of a wide range of diseases, this model may have broad implications for understanding the role of stress in health.”

276 healthy adults were exposed to the common cold virus and quarantined and monitored five days. Signs of infection were measured.

In a second group, 79 participants were assessed for their ability to regulate the inflammatory response and then exposed to a cold virus (rhinovirus) and monitored for the production of pro-inflammatory cytokines. Cytokines are the chemical messengers that trigger inflammation. The findings indicated that those who were less able to regulate the inflammatory response as assessed before being exposed to the virus produced more of these inflammation-inducing chemical messengers when they were infected.

Researcher Dr Cohn stated in an interview with  Science Daily

“The immune system’s ability to regulate inflammation predicts who will develop a cold, but more importantly it provides an explanation of how stress can promote disease,” Cohen said. “When under stress, cells of the immune system are unable to respond to hormonal control, and consequently, produce levels of inflammation that promote disease. Because inflammation plays a role in many diseases such as cardiovascular, asthma and autoimmune disorders, this model suggests why stress impacts them as well.”

He added, “Knowing this is important for identifying which diseases may be influenced by stress and for preventing disease in chronically stressed people.”

Stress and Breast Cancer

Until recently, the jury is out regarding a link between stress and breast cancer.  The results are not conclusive. A review conducted in Romania included a total of 52 studies from 1966 to 2016, investigating the relationship between stress and the occurrence of breast cancer. These studies involved over 29,000 patients and the results were divided into three categories:

• 26 positive articles linking personal traits, stressful events and breast cancer,
• 18 negative articles that did not confirm their hypothesis and
• 8 articles that could not be classified.

The review concluded:

there is “a possible association between stress and cancer, especially regarding stressful life events. In the absence of a meta-analysis and taking into account the methodological heterogeneity of the studies, the results are difficult to interpret and the role of chance is difficult to exclude”

In layman’s terms, there is a possible link between breast cancer and stress, however, the results are difficult to interpret once you include the element of chance into the analysis.

However, although conducted on mice, a more recent study may yield more conclusive information.

The study published in March 2019, conducted by the Basel University and Hospital in Switzerland, found concentrations of stress hormones cortisol and corticosterone were higher in mice with breast metastasis than those without. Leading to the conclusion that stress is linked to breast cancer metastasising.

In addition, they found that “glucocorticoid receptors” were very active in these metastatic tumours. These glucocorticoid receptors bind to stress hormones, including some chemicals prescribed for chemotherapy side effects.

Stress and Memory

Stress has also been shown to impact the ability to learn in a study conducted by Yale University, it was found that long-term stress damaged the hippocampus, a brain area involved in learning and memory and found it had reduced in size. Patients with posttraumatic stress disorder (PTSD) from Vietnam combat and childhood abuse showed a reduction in the volume of the hippocampus when checked with MRI.

However, not all stress affects memory loss, A review on the impact of stress on body function found that some stress can improve the function of the brain and therefore memory. These conditions include non-familiarity, non-predictability, and life-threatening aspects of imposed stimulation.