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What causes heart disease part 43

29th December 2017

What is stress?

I have talked about stress quite a lot, but as many people have pointed out, the word itself is meaningless. Or perhaps it would be more accurate to say that is has too many meanings, or that it means different things to different people.

Paul Rosch, a very brilliant man1, told me that when he was first looking at stress soon after the Second World War, he was working with Hans Sayle, a Hungarian. Sayle often commented that, had he understood English better, he would have used the word strain, not stress. He fully understood that ‘stress’ is the thing that creates ‘strain’ on the body. It is strain that matters, not the stress.

This, I think, is absolutely critical. You can look at some people’s lives and they may seem highly ‘stressful’, whereas others appear to be relaxed, and avoiding stresses wherever possible. However, you have no idea at all who is under the greater strain.

I remember a cardiologist, many years ago, pointing to an elderly woman who had just had a heart attack. ‘She lives in an idyllic cottage in the middle of the country, married, with loving children. No stress at all. So, don’t tell me stress causes heart disease.’ I merely shrugged. How could the cardiologist possibly know what was going on under the surface?

Perhaps her husband came home and beat the living daylights out of her every Saturday night. I remember seeing another lady, a few years earlier, who was deeply upset because she had been in hospital for an operation, and whilst there her husband had her two, very large, dogs put down.

Yes, she loved the dogs, but her main anxiety was that she had bought them for protection. When her husband went out for an evening and drank, he would come home and beat her mercilessly. She had bought the dogs for to keep her safe, now they were gone.

This couple were upstanding members of the community. They were regarded as having a perfect marriage and a perfect life. He was a magistrate and a local businessman, she ran a couple of charities. Having heard her story, I later watched them together, smiling and a laughing at local events. This was after I knew what actually went on in the home. Superficially, I could not tell anything was amiss between them.

On the other hand, some people can appear to lead lives that are full of stressors, yet can cope very well. Probably because have good physical and psychological resources, and are highly resilient. They usually have many other supportive factors in their lives. A loving partner, friends, family, and suchlike.

I think we are all also guilty of deciding that what causes us strain, will also cause someone else strain, and vice-versa. In fact, identical stressors can create very different effects. I give a few lectures every year. I quite enjoy it, I feel in control, and confident that I am good at giving talks and I find the process positive and enjoyable. However, I know of people who find the idea of standing up in front of other people absolutely terrifying. To them, giving a lecture would create massive negative strain.

In short, we cannot know the strain that someone else is under by looking at what they do, or how they act. Even massive events, such as having a partner die, will not have the same impact. For most of us this would be shocking and terrible. However, if your partner has been an abusive bully for thirty years, their death may come as a relief. Yes, it is all complex stuff indeed.

The reality is that, if you want to know if someone has suffered a level of negative stress, sufficient to have damaged them, you have to measure it. Yes, the dreaded objective medical science. Of course, before measuring things you have to have a hypothesis to test.

The hypothesis here is reasonably straightforward. It is as follows. Long term negative stressors (or one overwhelming acute event) can create damage to the neuro-hormonal system that coordinates the physiological reaction to strain. This, in turn, has negative physiological effects that can lead to serious disease e.g. CVD, or diabetes, or both.

If a tiger walked in the room, we would all react in pretty much the same way. Sudden terror. This would activate a vast array of different responses, and this reaction starts in the hypothalamus – deep within the brain. When stimulated, the hypothalamus releases hormones that, in turn, activate the pituitary gland to release further hormones. These hormones travel to the adrenal glands where the stress hormones are synthesized. Cortisol, adrenaline (epinephrine) and suchlike. This is called the Hypothalamic-Pituitary-Adrenal axis (HPA-axis).

The stress hormones that are released, speed up the heart rate, release glucose into the bloodstream, dilate the pupils, shunt blood supply from the guts to the muscles, and suchlike. At the same time the unconscious nervous system, which is tightly interwoven with the HPA-axis, lights up, and this puts every other system in the body onto ‘fight or flight’ mode. The blood pressure goes up, sweat glands are activated, blood clotting factors are released, and so on and so forth.

This is all normal, and natural and, assuming you survive, after about twenty minutes, or so, all systems start to wind back down to ‘normal.’ If the fight or flight system switches on ‘accidentally’ due to a perceived threat, that is not a real threat, this is usually called a panic attack. Which is why some people go nuts on aeroplanes and try to open the doors at 35,000 feet. In the midst of a panic attack the conscious mind is over-ridden, as the persons ‘inner chimp’ desperately tries to flee the situation. [The ‘Inner chimp’ is the part of the brain fuelled on impulsive emotion and gut instinct].

Some people who suffer from post-traumatic stress disorder (PTSD) are far more likely to see threatening situations all around them, and trigger panic attack mode far more often than others. Their fight or flight system has been set to super-sensitive mode. A child shouting may trigger the memory of a battlefield attack. Ditto a plane passing overhead, or a car changing direction rapidly. Not easy to live in a state of hair-trigger fight or flight.

Children who have been physically, or sexually abused have much the same hair-trigger systems in place. They live life on high alert, and are ready for fight or flight at any time. Billy Connolly, a Scottish comedian, who was abused when he was a young boy, always said he did not like being touched. It brought back memories that setoff deep, negative reactions.

All this is well known, and widely accepted. What is less widely accepted is that repeated activation of fight or flight can, in time, lead to a breakdown/burn-out/dysfunction of the HPA-axis and the unconscious nervous system – usually called the autonomic nervous system. In part, this is because people have steadfastly measured the wrong things, at the wrong times.

Perhaps the single greatest ‘measurement’ problem is to look at cortisol levels only n the morning. Cortisol is a key ‘stress’ hormone that is released in response to stressful situations. It also naturally fluctuates during the day. It rises to its highest level in the morning, just before you wake up, then it drops. Then rises and falls during the day.

Researchers, looking to link ‘strain’ to heart disease, and diabetes, and suchlike, have made the mistake of only measuring early morning cortisol in those with CVD, and found it to be lower than normal. They have then stated that HPA-axis dysfunction cannot be an underlying cause of CVD and/or diabetes – or any other serious medical condition.

This, of course, is exactly the wrong interpretation. If the HPA-axis is damaged, the normal rise and fall of cortisol, will break down. Or, to put it another way. A burnt-out HPA-axis leads to ‘flat-line’ cortisol production. It gets pumped out at the same rate – no matter what is going on Therefore, if you measure the cortisol level in the morning, in those with HPA-dysfunction, it can appear to be low, not high.

The correct way to diagnose HPA-axis damage, is to take regular cortisol measurements over a twenty four hour period. This was known by a Swedish researcher called Per Bjorntorp, who used hourly measurements of cortisol, to see what the flexibility of the HPA-axis was in people suffering from ‘cardio-metabolic disease.’ That is, people who have the ‘metabolic syndrome.’

The metabolic syndrome is a group of abnormalities that are often found clustered together. Abdominal obesity, high blood pressure, raised blood sugar levels (sometimes high enough to be called type II diabetes), raised clotting factors, high triglycerides/low HDL, higher LDL levels, high insulin levels.

This syndrome is also (has also been) called: insulin resistance syndrome, pre-diabetes, syndrome X and Reaven’s syndrome. Whatever you call it, it is the same thing. It is associated with a greatly raised risk of CVD. Around six-fold in some studies a.k.a. 600%.

Per Bjorntorp did a series of studies looking at HPA-axis dysfunction, and the metabolic syndrome, and he concluded that the underlying cause of the metabolic syndrome was indeed HPA-axis dysfunction. Here, I quote from his paper. ‘The metabolic syndrome – a neuroendocrine disorder?’

‘Central obesity is a powerful predictor for disease. By utilizing salivary cortisol measurements throughout the day, it has now been possible to show on a population basis that perceived stress related cortisol secretion frequently is elevated in this condition. This is followed by insulin resistance, central accumulation of body fat, dyslipidaemia and hypertension (the metabolic syndrome). Socio-economic and psychosocial handicaps are probably central inducers of hyperactivity of the hypothalamic–pituitary adrenal (HPA) axis. Alcohol, smoking and traits of psychiatric disease are also involved. In a minor part of the population a dysregulated, depressed function of the HPA axis is present, associated with low secretion of sex steroid and growth hormones, and increased activity of the sympathetic nervous system. This condition is followed by consistent abnormalities indicating the metabolic syndrome. Such ‘burned-out’ function of the HPA axis has previously been seen in subjects exposed to environmental stress of long duration.’ 2

It shouldn’t really be a great surprise that if you damage the HPA-axis/autonomic nervous system that you will end up with the metabolic syndrome. The short-term effects of activating the flight or fight system are to: raise blood pressure, raise blood clotting factors, raise blood sugar levels, raise LDL, and direct energy stores out of subcutaneous fat.

If this becomes a chronic state, you will end up with chronically: raised blood pressure, raised blood clotting factors, insulin resistance/type II diabetes and increased abdominal fat/central obesity, as fat stores are moved from the subcutaneous to the central fat stores.

We have a perfect model confirming this sequence with Cushing’s disease. This is a condition where excess cortisol is produced in the adrenal glands (usually due to a small cortisol secreting tumour). The long-term effects of Cushing’s disease are:

  • Raised blood pressure
  • Raised blood clotting factors
  • Insulin resistance/type II diabetes
  • Raised VLDL, low HDL (dyslipidaemia)
  • Central obesity
  • Greatly increased risk of CVD, around 600%

In short, long term increased cortisol production, creates a severe form of the metabolic syndrome, and a very high rate of CVD.

I suppose the final link in the chain is to look at what happens if we prescribe people cortisol. In truth, we do not do this, not exactly. Instead, we prescribe them corticosteroids. These are often just called ‘steroids’. They are used to treat inflammatory conditions, such as asthma, Crohn’s disease, Rheumatoid arthritis and suchlike.

All the prescribed corticosteroids are synthesized from the basic cortisol template. Cortisol is also called a corticosteroid, because it is a steroid hormone manufactured in the ‘cortex’ of the adrenal gland. One commonly prescribed corticosteroid is prednisolone, and the chemical structure of cortisol and prednisolone can be seen in the two diagrams.

 

If you prescribe steroids long-term, they too cause insulin resistance, then the metabolic syndrome, then type II diabetes, and much higher risk of CVD. The risk of CVD is increased by, up to, 600%. 3

Personally, I see this whole issue as a bit of a ‘slam dunk,’ where all the evidence fits together in an almost perfect causal chain:

Bjorntorp, in a series of well controlled studies, demonstrated that environmental ‘stressors’ can lead to HPA-axis dysfunction/physiological strain. This, in turn, leads to the metabolic syndrome. The metabolic syndrome, in turn, leads to a vastly increased risk of CVD.

PTSD is also a condition where the HPA-axis is dysfunctional4, and the rate of CVD is vastly increased5. Equally those who are victims of childhood abuse demonstrate HPA-axis dysfunction6 and a greatly increased risk of CVD7. Severe depression is also associated with HPA-axis dysfunction8 and a greatly increased risk of CVD9.

The key hormone in this process appears to be cortisol, because a high level of cortisol, independently of HPA-axis dysfunction, also leads to the metabolic syndrome, and a very high rate of CVD. In addition, if you prescribe corticosteroids they, too, lead to the metabolic syndrome and a very high rate of CVD.

Which of the elements of the resultant metabolic syndrome are most important? This is not entirely clear. Is it the raised blood pressure, the clotting factors, the high insulin or sugar? To an extent it does not matter that much. If you can get rid of the underlying cause, they will all disappear.

Next blog. How to get rid of the underlying cause?

 

1: https://www.stress.org/about/chairmans-blog/

2: https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0007114500000957

3: http://www.bmj.com/content/345/bmj.e4928

4: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3182008/

5: https://www.ncbi.nlm.nih.gov/pubmed/27566327

6: https://www.ncbi.nlm.nih.gov/pubmed/15471614

7: https://www.ncbi.nlm.nih.gov/pubmed/24923258

8: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC181180/

9: https://academic.oup.com/eurheartj/article/35/21/1365/582931

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