April 10, 2019

expert reaction to study looking at stress related disorders and risk of cardiovascular disease

Research published in the BMJ demonstrates that stress related disorders are associated with multiple types of cardiovascular disease.

Dr Katja Gehmlich, Associate Professor of Cardiovascular Science, Radcliffe Department of Medicine, University of Oxford, said:

“This elegant study highlights the importance of psychosociological factors for cardiovascular disease, especially for heart failure, a condition that puts a massive burden on health care systems.  Developing the idea of the study further, stress reduction may have promising long term benefits for cardiovascular disease.

“Comparing siblings as a key of the study design makes it more powerful: siblings often share similar genetic setups, lifestyle and other socioeconomic factors, such as education or exposure to environmental stressors, hence an association of a parameter – here, stress – with cardiovascular disease is easier to identify.  However, one of the limitations is that it is an association study – it does not provide direct proof that stress causes cardiovascular disease.

“Therefore it is necessary to research the underlying molecular mechanisms in future mechanistic studies, with the aim to prevent cardiovascular disease even in individuals exposed to stress.  Further research should also test the direct causal relationship and whether intervention, i.e. stress reduction, has indeed a measurable beneficial outcome on cardiovascular disease.”

Prof Sir Richard Peto, Professor of Medical Statistics and Epidemiology, University of Oxford, said:

“This new Swedish study doesn’t mean that stress causes heart attacks, because it couldn’t allow for any systematic differences in smoking, drinking or obesity.  A large UK study has shown that, after allowing properly for such things, there is no material difference in mortality between people who were stressed and people who weren’t¹.

“Smoking causes many different illnesses, and people who smoke are more likely to need to attend hospital than those who don’t.  Perhaps because of this, this new Swedish study has found more heart attacks in people who had previously attended hospital, maybe for some other medical reason, and whose hospital records had noted that they were stressed, than in the general population who hadn’t necessarily attended hospital at all.  But, people who have attended hospital for other reasons may well be at above-average risk of heart disease and lung cancer.

“So, this new result doesn’t tell us whether stress is independently associated with vascular disease, and it doesn’t even tell us whether stress is associated with any of the major risk factors for vascular disease.”

1 Lancet 2016; 387: 874-881.

Dr James Thompson, former Senior Lecturer in Psychology, UCL, said:

“Although both the authors and the Editor have rightly been cautious, this is a strong indication, based on a sibling control study, that stressful events probably have an adverse impact on cardiovascular health.  The absolute levels are low, even in the first year after exposure, and once over that first year, there is not too much to worry about.  However, the supposedly ‘exposed’ group (10.5 cardiovascular events per 1000 person years) simply got a stress diagnosis, which might mean that they are anxiety prone, a fact bolstered by finding that their ‘unaffected’ siblings also have higher cardio-vascular problem rates (8.4 cardiovascular events per 1000 person years) than the matched ‘unexposed’ population (6.9 cardiovascular events per 1000 person years).  Perhaps all this study shows us is that anxiety-proneness is correlated with cardiac problems.”

Prof Sian Harding, Professor of Cardiac Pharmacology, Imperial College London, said:

“This is a powerful and well-designed study, with the advantages of large numbers; matching to both sibling and population controls; and detailed psychiatric and cardiovascular history.  It confirms a large body of previous evidence linking acute stress to cardiovascular outcomes in specific situations such as sudden arrhythmic cardiac death and Takotusbo cardiomyopathy.  The time-dependent effects of acute events, with risk initially high but declining over a year, have also been noted previously.  However, it demonstrates in addition the range of cardiac conditions which show the association with stress, such as thrombosis and heart failure, as well as the extension to cerebrovascular disease.  It is particularly interesting that this is in a relatively young cohort, where incidence is generally lower, and risk is independent of sex and family history (and by implication genetic background).

“One confounder is that some of the risk factors for psychiatric disease here are overlapping with those for cardiovascular events: low family income; divorced or widowed; other somatic illness.  They note that there is no information about lifestyle indicators (e.g. alcohol intake or smoking) which can be intertwined with either condition.  Overall, this is an important addition to the knowledge linking stress to cardiovascular events.”

‘Stress related disorders and risk of cardiovascular disease: population based, sibling controlled cohort study’ by Huan Song et al. was published in the BMJ at 23:30 UK time on Wednesday 10 April 2019.

Declared interests

Dr Katja Gehmlich: “No conflicts of interest.”

Prof Richard Peto: “I have no relevant interests to declare.”

Dr James Thompson: “No conflicts that I know of.”

Prof Sian Harding: “I work on a specific stress-related cardiac condition called Takotsubo cardiomyopathy, but I don’t think this is a conflict.”