Psychological distress and death from cardiovascular diseaseBMJ 2012; 345 doi: http://dx.doi.org/10.1136/bmj.e5177 (Published 31 July 2012) Cite this as: BMJ 2012;345:e5177
The association between psychiatric disorders and cardiovascular disease is often reported in observational studies, but the question of reverse causation has always loomed large. In a linked research study (doi:10.1136/bmj.e4933), Russ and colleagues investigated the association between psychological distress and death from cardiovascular disease (recorded on death certificates) by examining data on more than 60 000 people from 10 large cohort studies based on the Health Surveys for England.1 The authors excluded early deaths (in the first five years of follow-up) and therefore the likelihood of reverse causation. Although the possibility of confounding can never be completely excluded, after adjusting for several “lifestyle” factors and cardiovascular disease risk factors, the authors still found a dose-response association between psychological distress and death from cardiovascular disease. These findings add to evidence that suggests a causal association between psychological distress and cardiovascular disease.
In the English health surveys used by Russ and colleagues, psychological distress was measured using the General Health Questionnaire (GHQ).2 This assessment of mental health status is widely used and shows good agreement with more detailed assessments of depression and anxiety, conditions that are best represented along a continuum of severity in population studies.3 No obvious point separates people who report symptoms of depression or anxiety that meet diagnostic criteria from those who report similar symptoms below the diagnostic threshold. The current study found that an increased risk of cardiovascular disease exists along the whole of this continuum in a dose-response manner. Forty per cent of the sample scored at least 1 on the GHQ, and an association with subsequent death from cardiovascular disease was seen even at these low scores. The prevalence of depression and anxiety disorders is about 7.5% in the United Kingdom.4 It is now clear that an association between psychological distress and cardiovascular disease exists well below the threshold that would lead to a diagnosis of depression or anxiety or require specific treatment.
Several plausible mechanisms might explain how psychological stress can lead to cardiovascular events.5 6 The stress response involves the hypothalamus-pituitary-adrenal axis and the autonomic system; changes in inflammatory cytokines might also be implicated. What is the difference, if any, between stress and psychological distress? Stress is usually defined as the response of an organism to external stressors. One idea that has gained popularity is that the physiological and psychological responses to psychological stressors are designed to protect the organism but that the body’s response can also have harmful effects on health.7 It seems reasonable to hypothesise that not “coping” with psychological stressors will lead to symptoms of depression and anxiety; in other words, psychological distress and psychological stress are the same thing. Using the GHQ or other similar measures to assess sub-threshold symptoms at a given time point may be one way of assessing stress levels. It is also important to distinguish between acute and more chronic forms of stress.5 6 Watching the English football team lose a penalty shootout, which has also been associated with cardiovascular events,8 may be acutely stressful. The stress measured by the GHQ is more likely to be chronic.
It is difficult to make the leap from the current observational evidence to suggesting that reducing stressors in the environment or changing the psychological interpretation of stressors will help to prevent cardiovascular disease. But, if psychological stress and distress are causes of cardiovascular disease, what implications does this have for prevention and treatment? For those people who meet diagnostic criteria for depression and anxiety, several effective psychological and drug treatments are available. However, what should be done about the much larger numbers of people who report symptoms on the depression-anxiety continuum but do not meet diagnostic criteria?
Obvious sources of stress such as workplace stress could be modified.6 It is also worth considering how societal stresses related to inequalities and socioeconomic status might contribute to the incidence of cardiovascular disease.9 However, an attempt to produce a stress-free existence seems utopian and ignores the idea of “good stress.”7 People vary greatly in their response to stressors, and some people even seek out stressors to provide a challenge and a sense of achievement. Avoiding stressors might also lead to more anxiety in the long run.10
A more useful approach could be to change the psychological interpretation of stressors, because this might reduce their biological impact. Cognitive behavioural therapy is, in part, designed to help people change the way they interpret stressors and thereby reduce the impact of stress.11 Individual and group cognitive behavioural therapy has been shown to be an effective treatment for depression and anxiety, but not, sadly, for preserving the health of the English football team’s supporters. Even if we could improve our understanding and use of cognitive theories in the population to increase resilience to stressors, there is currently no evidence that these methods can be disseminated to the population at large to help people reduce perceived stress.
Cite this as: BMJ 2012;345:e5177
Competing interests: The author has completed the ICMJE uniform disclosure form at www.icmje.org/coi_disclosure.pdf (available on request from the corresponding author) and declares: no support from any organisation for the submitted work; no financial relationships with any organisations that might have an interest in the submitted work in the previous three years; no other relationships or activities that could appear to have influenced the submitted work.
Provenance and peer review: Commissioned; not externally peer reviewed.