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Have you ever heard a person in poor health being told “Well, you’ve got to stay positive, that will help”? This seemingly common idea is currently under significant scientific investigation. Indeed, the debate about the degree to which psychological processes can directly influence physical health has received special attention recently. A special supplement of the Annals of Behavioural Medicine directly addressed this topic in February this year and a recent article in the Lancet explored this issue, cautioning us that the relationship between a positive psychological orientation and cancer survival remains unclear .
Linking the nervous system to the immune system
In a previous article, I discussed the direct and indirect links between beliefs about illness and physical health for people with heart disorders. What we did not consider however was how this direct influence may be happening. Enter “Psychoneuroimmunology” — the field of study exploring the direct link between the nervous system and immune system, including the endocrine system, covering hormones. The brain controls these systems. Part of psychoneuroimmunology is the study of degree to which the action of these systems is impacted on by mental health and the way we think and process information around us. This is of particular interest when we exam the relationship between psychological experience, nervous/immune/endocrine systems and health conditions.
One health condition much researched in relation to psychoneuroimmunology is cancer, not only because of the enormously high mortality and morbidity rates associated with cancer globally, but also the psychosocial context of cancer. Cancer was historically highly stigmatised with the idea that a cancer-prone personality existed . The concept that one’s personal characteristics were related to the illness lead to the idea that adopting a positive, active personality would be protective. Within modern terms, scientists now investigate the degree to which psychology may directly influence cancer pathology.
Stress and cancer
Let us first look at the biological aspects of stress and cancer. In an opinion article based on a systematic review of the literature, Ondicova and Mravec (2010) explore how the nervous system affects cancer “etiopathogenesis”, or, in plain English, the biomedical cause and development of a disease or health condition . Cortisol is released in response to physical and psychological stress, and appears to reduce immune cell function, which may influence tumour growth. Norepinephrine (also known as noradrenaline) is also released in response to stress when epinephrine (also known as adrenaline) is released. Norepinephrine is implicated in the psychobiology of depression. Norepinephrine has been shown to induce cancerous cell growth in mouse animal model studies , but reduce the migratory activity of human ovarian carcinoma cells . However, other elements of the nervous system exist to protect us from stress. For example, prostaglandins, which are thought of as messenger molecules throughout the body, act on a huge variety of cells and processes, including muscle cells, blood cells and hormone regulation. These prostaglandins can actually decrease the number of malignant cells in animals . Ondicova and Mravec state that “cancer can be thought of as a process that overcomes not only the protective mechanisms of the immune system but also the protective influences of the nervous system” . Nevertheless, overall the studies of how biological responses to stress might influence tumour growth provide an unclear picture and there is a clear requirement for further studies to properly understand this issue.
The connection between cancer and psychology
So, then, what has this to do with psychology? Well, the link that has been hotly debated is that of positive psychology and cancer. Positive psychology researches happiness, quality of life and strengths, exploring how to ensure a sense of wellbeing. Research on optimism and benefit finding has suggested that having a positive outlook can influence illness progression and management. Specifically, a recent review article in a special issue exploring positive psychology and cancer considers how positive psychology might influence cancer pathology .
The review examines studies that show cortisol could be reduced by benefit-finding among breast cancer patients. Indeed, people who engaged in positive thinking (here self-enhancement and self-affirmation) had lower cardiovascular responses to stress. As such, the potential link between your conscious psychological experience and physical health is outlined. The argument then states that psychological responses to stress affect neuroendocrine and immune functioning, which in turn influence tumour growth. The authors of the review highlight the seemingly large and obvious link between mental health and cancer. Being able to adequately deal with stress should, according to this pathway, help protect us from cancer. However, other authors point to the lack of specific pathway and high quality evidence to support this link [3, 8].
Cognitions leading to stress affect biology
There is clearly a complex relationship between life experiences, cognitions, stress and illness, including cancer. Psychological experiences have a basis in brain chemistry and biology, and it appears that cognitions leading to stress then have an affect on biology. A basic example is that when stressed, we experience muscle tension and increased heart rate. The strength of the relationship between thoughts and pathologies such as cancer cannot yet be determined and as such, results should be viewed with a healthy scepticism. Psychological interventions to improve psychological health, reduce negative thinking, stress and anxiety may be beneficial not only for mental health and quality of life, but also potentially for physical health.
- Ondicova K and Mravec B. Role of nervous system in cancer aetiopathogenesis. Lancet Oncol. 2010 Jun;11(6):596-601.
- Sontag, S. Illness as Metaphor. New York: Farrar, Straus & Giroux. 1978. ISBN 0-394-72844-0
- Coyne JC and Tennen H. Positive psychology in cancer care: bad science, exaggerated claims, and unproven medicine. Ann Behav Med. 2010 Feb;39(1):16-26.
- Sood et al. Adrenergic modulation of focal adhesion kinase protects human ovarian cancer cells from anoikis. J Clin Invest. 2010 May 3;120(5):1515-23. doi: 10.1172/JCI40802. Epub 2010 Apr 12.
- Bastian et al. The inhibitory effect of norepinephrine on the migration of ES-2 ovarian carcinoma cells involves a Rap1-dependent pathway. Cancer Lett. 2009 Feb 18;274(2):218-24. Epub 2008 Oct 11.
- Wang D and Dubois RN. Prostaglandins and cancer. Gut. 2006 Jan;55(1):115-22. Epub 2005 Aug 23.
- Aspinwall LG and Tedeschi RG. The value of positive psychology for health psychology: progress and pitfalls in examining the relation of positive phenomena to health. Ann Behav Med. 2010 Feb;39(1):4-15.
- Coyne et al. Positive psychology in cancer care: A story line resistant to evidence. Ann Behav Med. 2010 Feb;39(1):35-42.