The body’s response to stress is partly regulated by a system known as the hypothalamic-pituitary-adrenal (HPA) axis. The HPA axis is a network of connections which allows the brain to communicate with the endocrine system (a system which controls the levels of different hormones in the body). It encompasses the hypothalamus and pituitary glands, located at the base of the brain, and the adrenal glands, located above the kidneys. The HPA-axis regulates a range of important bodily processes, including immune responses and digestion. One of the ways it does this is by producing a hormone called cortisol. Previous work has found that abnormal patterns of cortisol release can occur in response to stress.
Whilst cortisol levels can be measured in numerous ways, including through saliva and urine, one of the most reliable and newest methods is through the hair (hair cortisol concentration). Though it is well-established that cortisol production can be altered by stress, previous attempts to examine how cortisol levels change in response to life stressors has led to contradictory findings. This is partly due to studies measuring stress in different ways and using small sample sizes.
CoMorMent researchers, therefore, sought to examine the relationship between life stressors and levels of cortisol in a large sample of women. Women attending routine cancer screening in Iceland were asked if they would like to participate in the study. Those who did were asked to provide a hair sample (for measuring cortisol) and to fill in the Life Stressor Checklist-Revised, a 30-item questionnaire in which participants indicate whether or not they have experienced specific stressful life events. The questionnaire covers multiple stressful events including the death of a loved one and natural disasters and contains seven items referring to personal experiences of physical or sexual violence.
Although the women were recruited from the general population, 42% had experienced physical and/or sexual violence. For 70% of these women, the first instance of violence occurred in childhood. The researchers found that the more stressful life events the women experienced, the higher the concentration of cortisol in their hair. They also found that physically and sexually violent stressful life events were more closely related to cortisol levels than non-violent stressful life events. For each violent event, levels of hair cortisol rose by 10%.
These findings show that experiences of violence may increase the amount of cortisol secreted by the HPA-axis, which in turn could disrupt the normal functioning of the body. This is particularly important given how many women experience violence – 42% in this study and at least one in three worldwide.
