Beating the cardiovascular consequences of stress
Emotional stress can have a major negative impact on cardiovascular function - an effect which must originate in the forebrain. Research in neurocardiology is busy working out the organisation and functions of the brain that are responsible for these effects but what do we do in the meantime. Let's start with the bad news.
Since ancient times, physicians have hinted at the damaging effects of stress on cardiovascular health. The Persian physician Avicenna used wolves to generate mental stress in lambs and often observed how this could lead to the death of the lambs.
Numerous studies have demonstrated the link between acute mental stress and cardiovascular disturbances. Physicians no longer hint at the connection between stress and heart health; the evidence for the connection is considerable.
Stress, anger and anxiety influence the development of atherosclerosis, hypertension, myocardial schema and infarction, and cardiac arrhythmia formation - and if that were not enough - sudden cardiac death.
Epidemiological studies suggest that cardiovascular problems in a population frequently follow natural disasters in a region. Life stress effects such as the death of a relative or an accident can be contributing factors in the pathogenesis of cardiovascular disturbances in the individual.
The evidence points to the involved integration between the emotional and autonomic centres in the brain. Coordination between the activities of neurons in autonomic control sites of the cerebral cortex and the limbic system are implicated. The insular and infra limbic cortices as well as a brain structure called the amygdala play major integrative roles in the control of the cardiovascular system.
This sort of sounds like bad news - so what does it mean for us in simpler terms. What can we do about it?
The relationship between stress and cardiovascular disturbance may be well documented but the nature of the individual's response is not. One of my mentors taught me that often the difference between fear and excitement is often as simple as how you breathe. There is some truth in this - but maybe not the whole truth.
It might start with symptoms of fatigue and pain - or maybe sleeplessness that leads to a GP appointment, maybe a hospital referral and then when no medical explanation can be found a label - "stress related problems". A psychologist might look at behaviour, personality and cognition and with luck a therapy can be found that deals with the symptoms. Often the problems remain and especially when the client is challenged to experiment with a new bahaviour which causes extra stress. Giving advice to "just relax more" or "learn to breath slowly" may not be sound advice.
Using a biofeedback system such as a NeXus unit with appropriate sensors can provide a more inciteful perspective on what is happening with the client.
Stress can be introduced to a client with something like the Stroop Test, mental arithmetic, simulated public speaking or something similar. The use of wolves tends to be frowned upon.
Research looking at the individual’s response to a Stroop Test have been interesting.
Some researchers have shown significant increases in both blood pressure and heart rate in response to mental stress. Some results demonstrate a link between so called type-A personality and clinical cardiovascular disturbances. Interestingly some studies indicate either a negative relationship between these factors or no relationship at all. These conflicting results suggest that it is not the nature of the stress that is the determinant of damaging consequences but something to do with how each individual reacts to and then processes the stress.
Using biofeedback or so-called psychophysiological approaches we can “introduce a little stress into someone’s life” and observe how they respond. Furthermore we can show them specifically how they respond to stress events and teach better strategies.
In stress profiling we would normally have a baseline period when the client is maybe sitting quietly and reading a newspaper for example. We could then then have a number of phases of introduced stress followed by a period of relaxation and recovery. This would be repeated a number of times.
With the NeXus biofeedback system we might use what is called a psychophysiological stress profile (see sample data below). Rather than just focusing on measuring one physiological signal we would use multiple sensors and observe how each of these signals responds during the following typical sequence of events.
- Baseline - for 6 minutes the client simply reads a magazine in silence
- Stress test one - a few minutes of mental stress
- Repeat the stress and relaxation events twice more
- Breathing exercise.
Total time for the stress profile - around 20 minutes. The sensors typically applied would be
- skin conductance
- hand temperature
- Respiration rate
- heart rate either via ECG or BVP measurement
- Muscle tension (eg EMG from the trapezius muscles of the left and right sides)
By using this approach we can see more clearly how the individual’s body reacts during relaxation and during stress. We can see whether the client is actually able to relax when the stress is no longer present. The BioTrace+ software automatically marks the baseline, stress and relaxation segments (shown in the coloured bands in the stress profile)
If we are in a relaxed state, respiration tests to be slow and deep, heart rate is normal, the muscles around the neck are relaxed and the skin of the hands is warm and dry. When we are in an alert state a change in these signals can be observed. An important fact is that the nature of this change varies from person to person. When a person is challenged with a mental task some people start to sweat, others tense their neck and shoulder muscles and others start to breath more rapidly or in a shallow way. It is important not to assume how a person will react to stress and how the person reacts to a simple mental task is a good starting point for how they are likely to respond to other stressful situations in life.
In the latest version of the BioTrace+ software, NeXus biofeedback system users have a psychophysiological stress profile available as part of the software. This can be used exactly as it is presented or modified to suit personal preferences. By following this protocol you have a very powerful tool and easy to use tool to measure and feedback to the client how they are responding to stress events. A fruitful discussion and strategy for change can more easily evolve from this. This technology eliminates guesswork and gives us some practical tools for dealing with the damaging effects of chronic stress.
For more about Neurocardiology see "Basic and Clinical Neurocardiology" Edited by Armour, AJ and Ardell, JL; Oxford University Press 2004