What Causes Heart Disease? Malcolm Kendrick’s Views

In this video Malcolm Kendrick, a Scottish doctor, points out the lack of cross-country correlation between cholesterol levels and heart disease rates.

In this video Kendrick explains why he believes that extreme stress — often caused by emigration — is a big reason for high rates of heart disease.

This view is supported by research by Michael Marmot and others on the social gradient: People higher in occupational level have better health than those below them. This seems to be because lower jobs are more stressful. The lower your job, the less control you have. Lack of control is the problem.

Kendrick’s view calls into question the usual interpretation of migrant studies. When persons emigrate across countries — from Japan to America, from India to England — they usually have higher heart disease rates in the new country This is often attributed to differences in diet — the old-country diet is presumed healthier than the new-country diet. Kendrick lays the blame elsewhere. He also makes an interesting point about Finland. Finland used to have a very high rate of heart disease. Kendrick points out that in the early 1950s, about 700,000 persons of Finnish descent were pushed by the Soviet government out of the Soviet Union and into Finland. Kendrick also mentions Roseto, Pennsylvania, a town created by emigration en masse from Roseto Italy. The old customs and social networks survived the move intact and the people of Roseto Pennsylvania were for many years remarkably healthy.

Previous posts on heart disease: Omega-3 and heart attacks (also here). The Framingham Study.

Thanks to Dave Lull.

Addendum: Kendrick on “The Great Cholesterol Myth.”

6 Replies to “What Causes Heart Disease? Malcolm Kendrick’s Views”

  1. Seth: Finland still has high rates of CHD. Causes, according to this: http://www.springerlink.com/content/b011711g64k05142/ , include high serum cholesterol levels, smoking, and hypertension. As per the first video, Australian aboriginals also have high rates of obesity, alcoholism, and diabetes, leading to high CHD rates.

    As for the “social gradient” theory of CHD, I think that has been definitively put to rest be Deary and Gottfredson: Childhood IQ is moderately strongly correlated with adult socioeconomic position. Lower IQ is also associated with increased rates of all-cause mortality (1, 2), cardiovascular
    disease (2–4), hypertension (5), contact with psychiatric services (6), and other negative health outcomes (7). These associations
    remain after controlling for socioeconomic position in early life. http://www.udel.edu/educ/gottfredson/reprints/2005scienceletter.pdf See also Gottfredson’s “Intelligence: Is it the epidemiologists’ elusive ‘fundamental cause’ of social class inequalities in health?” http://www.udel.edu/educ/gottfredson/reprints/2004fundamentalcause.pdf

    Further, as to “stress”, heart disease rates in German-occupied Europe during WW2, in The Netherlands and Norway for example, went down, exactly the opposite of what one would expect if stress were a cause.

  2. One has to wonder after all the failed nutrition research to what degree nutrition is a factor in heart disease. How does one go about making estimates in the first place if you don’t know what other factors are in play? It’s all guess in the dark.

    Robert Levenson’ and other emotion researchers find that if you have subjects watch a disturbing video of an arm amputation and are told to keep a poker face and show zero emotion in response to it, they have 2x the cardiovascular stress in heart rate and blood pressure as subjects who watch it and respond naturally. And generally, suppressing any emotion, positive or negative, causes much added cardio stress.

    Perhaps immigrants, especially from radically different cultures, must suppress a lot of emotion, or feel cognitively overwhelmed, and that causes heart disease. The depression research is showing great increases in heart disease among depressives, based on correlational studies — again more guessing, but interesting. Stress hormones like cortisol are tied to depression and heart disease.

    When you don’t know what you don’t know, you have to be very careful about making causal claims — it should be written on wind and running water!

  3. Dennis, the drop in heart disease during WW2 has been attributed to a dietary shift from meat to fish, which makes sense. Although Kendrick doesn’t believe in the value of omega-3, I do.

    “The social gradient” is an observation, not a theory — it can’t be “put to rest” unless the data turns out to be false. As for its explanation, sure, IQ could be important, especially in controlling what job you end up getting. Whether IQ remains important after degree of control over one’s job has been accounted for remains to be seen.

    A study that equates IQ across the groups being compared is the famous study of London transit workers in the 1950s that found that drivers of double-decker buses had a higher rate of heart attacks than the ticket takers on those buses. The first explanation was that the ticket takers got more exercise (presumably up & down the stairs); I have suggested they got more sunlight and stood much more so they slept better; others have suggested that driving in London traffic is stressful. No one has proposed that the crucial difference is IQ.

  4. Seth: Good points except, I think, for the last one: the London bus drivers vs. ticket takers doesn’t involve a social gradient. Or if there is one, it ought to be the drivers who are higher on the scale. The studies I’ve seen involving social gradients were workers with bureaucratic functions who had precisely defined positions and pay, but all doing sedentary work.

    As for the possibility of decreased CHD resulting from a switch to fish from meat, I really wonder whether those in the occupied countries had much access to fish. However, I haven’t seen any data on this. I haven’t heard that those in unoccupied countries like Britain had lower CHD rates.

  5. I would argue that the social gradient speaks against a stress-heart disease connection, not for it: Who works longer hours – the CEO or the blokes at the assembly line and in accounting? Who has a higher responsibility and thus more to worry about?

    I will admit that this is somewhat compensated by lower-level workers having to worry more about making ends meet, but I don’t think this comes close to making up for work-related stress – at least not in first-world countries where low-level workers are relatively well-off.

  6. Perhaps “stress” is the wrong word. People lower in the hierarchy have less control of their work and their working conditions. Working on an assembly line is the ultimate in terms of lack of control. Being the CEO is the opposite of that.

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