06/2019 – 12/2019
For a variety of diseases in human beings, ranging from depression to adverse reactions on the metabolism, it is assumed that acute psychological stress causes – or at least promotes – the development of such . Anxiety and stress disorders count to the most often occurring chronic diseases. In addition, stress is a complex construct that is affected by a wide range of factors, such as the economic and political situation or one’s descent [1, 2]. Moreover, psychological and physiological comorbidities commonly accompany stress-related diseases. For that reason, the need for methods to intervene with stress is increasing, especially since stress is reported to increase in our modern-day society .
As a response to stress, the human body increases the activity of the sympathetic nervous system (SNS) and the hypothalamus-pituitary-adrenal (HPA) axis. The latter results in a mechanism that induces the secretion of cortisol in the adrenal cortex, whereas the activation of the SNS causes the secretion of adrenaline/noradrenaline. Moreover, the SNS and its antagonist, the parasympathetic nervous system (PSNS), interfere with the cardiovascular system . Hence, the activity of the autonomic nervous system during stress can be indexed by observing the cardiovascular system . These alterations are quantitively reflected in increased cortisol secretion and decreased heart rate variability, amongst others .
The Cold Face Test (CFT), which is carried out by applying a cold stimulus to the face, mimics the diving reflex, a strategy to conserve oxygen by inducing bradycardia. Hence, the CFT interacts with the trigeminal nerve of the PSNS, creating a trigeminal-vagal stimulation. As a consequence, the interplay between PSNS and SNS shifts towards a higher contribution of the PSNS. Thus, the CFT intervenes with the pathway of stress reaction by inhibiting the contribution of the SNS. Whereas previous work has already shown a relationship between a fast CFT and reduced cortisol increases as well as enhanced mood during a stress task, it has not yet been investigated whether the effects of the CFT can actively reduce the physiological response to acute stress .
The first goal of this bachelor’s thesis is therefore to implement relevant features to assess the autonomic reaction to the CFT. Furthermore, the stress reduction will be evaluated, which is assumed to go in hand with the CFT stimulus. Thus, the analysis of the CFT-induced vagal stimulation and the suitability for inhibiting the SNS and HPA reaction are a further goal of this thesis. To realize this, a stress study will be performed by conducting the Montreal Imaging Stress Task (MIST) with and without application of the CFT . Last, the correlation between CFT reactivity and stress response will be investigated.
- Paul Foley and Clemens Kirschbaum. “Human hypothalamus–pituitary–adrenal axis responses to acute psychosocial stress in laboratory settings.” Neuroscience & Biobehavioral Reviews 35.1 (2010): 91-96.
- American Psychological Association. “Stress in America: The state of our nation.” Stress in America Survey (2017).
- Evangelia Charmandari, Constantine Tsigos, and George Chrousos. “Endocrinology of the stress response.” Annu. Rev. Physiol. 67 (2005): 259-284.
- Roberto La Marca, et al. “Association between Cold Face Test‐induced vagal inhibition and cortisol response to acute stress.” Psychophysiology 48.3 (2011): 420-429.
- Katarina Dedovic, et al. “The Montreal Imaging Stress Task: using functional imaging to investigate the effects of perceiving and processing psychosocial stress in the human brain.” Journal of Psychiatry and Neuroscience 30.5 (2005): 319.