Section: Science Life
An ETH study investigates the connection between stress and health|
When work causes stress...
In Switzerland 4.2 billion Swiss francs is lost every year owing to stress-related illnesses. Although much basic research has been done in many laboratories on the biological reactions to stress, experiments exploring the interdependency between everyday pressures and health under real-life conditions are still a rare. A research group at ETH is now carrying out a long-term study to investigate the connection. A few hundred members of ETH staff are included in the study.
By Jakob Lindenmeyer
"Everyone talks about stress, we measure" is what is written on a small box looking like one containing ampoules. Inside there are eight small plastic tubes, together with a detailed instruction on how to collect saliva samples. The content of these tubes, collected during the course of a day by the test subjects themselves, are then analysed to determine the levels of the stress hormone cortisol. The analyses are part of an ETH research project on the connection between psychosocial stress in the workplace and its biological consequences.
The research team around the physicians Joachim Fischer and Roland von Känel from the ETH Institute of Behavioral Sciences is carrying out a long-term, comprehensive study with 2,500 participants to determine under what conditions and how initially purely psychological stressors can precipitate measurable physiological changes. The aim of the study is to find out which factors can contribute to people staying healthy and fit and how chronic stress accelerates the ageing process.
Members of ETH staff as test subjects
In summer 2003 the researchers extended the numbers of test subjects to include all permanent staff members of ETH Zurich over 35 years of age. 355 returned the initial questionnaire that the team sent out and 280 of these took advantage of the free medical check-up. First results of this examination will be presented next week, on the 10th February at 6.15 p.m. in the Audimax of ETH Zurich.
Protection from the consequences of stress
So far, 145 members of staff volunteered to be included in an additional study, which is supported by the Swiss National Science Foundation. For this project the behavioural scientists have focused on two of the main systems involved in the development of arteriosclerosis, namely coagulation and a sub-class of the white blood cells called monozytes. In a first experiment, the team examines the effect of a repeated experimental psychological stressor on the activation of this subclass of white blood cells and on the coagulating process. In the second experiment, they investigated whether drugs known to be effective in secondary prevention of myocardial infarction, such as aspirin or beta-blockers, inhibit the influence of acute psychological stress on these systems. At this stage of the study, 25 members of ETH staff have already subjected themselves to “stress” in the laboratory, three times with a week apart between sessions. (1)
Such research on humans also serves to verify results from animal experiments. While the latter contribute to an understanding of and an explanation for biological mechanisms, they are unable to quantify the effects of human work-related stress, such as anxiety about the possibility of losing one’s job, low levels of decision latitude, anger or frustration about a “dictatorial” boss, on the risk of cardiovascular disease. “Such data can only be gained by long-term studies with a large enough sample of individuals,” justifies the leader of the research group, Fischer, the time and cost consuming methodology employed for the study. This study is differs from others in the field in two aspects: firstly because it includes a more comprehensive assessment psychosocial and work-related factors, but above all because it includes a more profound examination of possible biological mechanisms underlying the interaction between psychosocial stressors and adverse health outcomes.
Three-fold reaction to stress
“We know a considerable number of single factors that change under the influence of acute or chronic psychological stress,” explains Fischer. "These variables range from the pulse rate to the secretion of the stress hormone cortisol and to proteins involved in coagulation.” However, Fischer concedes that “very little is understood about the interdependence of the main systems responsible for biological reaction to stress”.
Under normal conditions, the first system, the parasympathetic nervous system, downregulates the heart rate and the activation of inflammatory processes within tissues. If an individual perceives danger or if a strong physical effort is required, the organism loosens this “stress brake”. This is when the effect of the second system kicks in, the sympathetic nervous system. The noticeable consequences: a rapid increase in heart rate. When the situation poses a high level of threat, the third system is activated. Hormones from the pituitary gland cause the adrenal gland to secrete large quantities of the stress hormone cortisol. As soon as the danger passes, this stress reaction abides and the three system return to the original condition.
Fit to fight
In the past, this delicately regulated reaction to stress provided evolutionary advantages because the organism was rapidly prepared to fight or flee when necessary. These reactive mechanisms raise the heart rate and the contractility of the cardiac muscles, expand the bronchi, and prepare the body for possible injuries.
These mechanisms make perfectly biological sense when, for instance, a mouse just manages to save itself from a cat attack by disappearing into its hole. Further up on the evolutionary ladder this biological reaction to stress can be released in mammals with the mere mental anticipation of danger, as when two primates face one another in a fight for hierarchy, for example, or when the pilot of a fighter jet has to make a night time landing on the deck of an aircraft carrier. But what is the use of preparatory reactions to stress if the boss keeps on handing out unsolvable tasks? One of the open questions is to what extent these systems are activated in response to the everyday life of an employee at work?
Vexation may damage the heart
Swedish researchers have shown that mini-stressors can in fact have quite deleterious consequences under certain conditions. Their studies in patients recovering from heart attacks revealed that after periods of excessive anger the risk of an attack was three-fold higher. Those patients who happened to be on Aspirin had a markedly reduced risk of a heart attack after periods of anger. British researchers found that people who carry out mundane tasks and have little room to participate in decision-making are four times more likely to eventually have a heart attack than employees in higher positions with more decision latitude. An earlier ETH study of the personnel of an intensive care unit (2) revealed a further peculiarity: Subjective perception of a given situation as highly stressful does not automatically trigger a danger biological reaction to the stress – and vice versa. In about two-thirds of the events where salivary cortisol levels revealed a sudden peak or a profound biological stress response, the individuals did subjectively not perceive themselves to be particularly stressed.
Biological wear and tear
Someone pursuing a hectic driving style in traffic, alternating between pushing down the accelerator and ramming on the breaks, is not surprised that this increases the wear and tear to the car. What happens, though, if everyday conditions release inappropriate and relentless biological reactions to stress, sometimes over a many years? Bruce McEwen, a US neuroscientist, coined the phrase “Allostatic Load” to describe the biological consequences of chronic and repetitive activation of the organism’s biological responses to external stressors. These are not confined to psychological stressors. For example, some individuals may respond to social stress by increasing smoking, which in turn adds the burden of a strong chemical stressor. Looking at chronic stress he found measurable functional changes very early on – long before irreversible damages became manifest. A long-term US study shows that 70 year-olds with high scores on Allostatic Load will die earlier or have a more profound decline in mental and physical capacity a decade earlier than their otherwise equally healthy 70 year-old counterparts with a low Allostatic Load.
The ETH research team extended the concept of McEwen's Allostatic Load to include possible dependencies between factors characterising the work-place and health. (3) In summer 2003 the team analysed 650 employees of a plane construction company during an entire day parallel to the activity of all three systems involved in the stress reaction mechanism. It was the first such comprehensive study anywhere in the world. Over a period of four days participants made notes of the subjective stress they felt, collected saliva samples to measure the levels of cortisol and were fitted, on the last day, with an instrument that measured heart rate and physical activity.
Research requiring patience
“Whether the dependencies that we were able to identify are clinically relevant won’t become clear for another 10 or 15 years, until we have completed the follow up on our over 2,500 participants from ETH, the Airbus and the Eurofighter industry,” says Fischer, “we have to be patient”. However, even long-term research positions are few and far between nowadays. Due to upcoming retirement of professor Karl Frey at the ETH Institute of Behavioral Sciences the long-term study would have had to be broken off at the half-way mark in 2007. Thus, the two heads of the research group looked around for other ways to continue their work. Roland von Känel is Professor for Psychosomatics since the beginning of this year at the University of Berne. (4) The head of the team, Joachim Fischer, has been offered a position at the US National Institute for Ageing (5) at the end of this year, an institution that was involved in the first phase of the project. One of the future research projects of the National Institute for Ageing will be to investigate the influence of office building architecture on the heart rate variability. The latter allows to estimate the activity of the parasympathetic nervous system, probably one of the key players in mediating between psychosocial factors and biological reactions.
Further research into health-relevant factors in workplaces that are characterised by time-pressure and uncertainty about the continuation of one’s job is highly relevant to our times. If, owing to demographic shifts and changes in retirement pension schemes, future populations of workers have to continue to work until the age of 70, there is a great need for a working culture that keeps them healthier for longer.
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