Orthodox vs. Alternative Theories of Disease

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What do we mean by 'cause' in disease?

A conventional doctor who talks about the causes of disease may have several things in mind. Sometimes the matter may be fairly straightforward. The cause of tuberculosis is the tubercle bacillus. The cause of malaria is the malaria parasite. These are easy causes to identify; the discovery that many diseases are due to infections was probably the main medical advance made in the nineteenth century. Even in such cases, however, it may be that individual susceptibility and other factors are involved in addition to the bacterium or virus.

Sometimes it is rather harder to be precise about the cause, even when a good deal is known about the matter. If a patient who smokes acquires lung cancer his doctor will think of smoking as the cause; but we know that there are many people who smoke for years yet do not suffer from lung cancer. In this respect smoking is a different sort of cause from, say, the measles virus. We think that pretty well everyone who comes into contact with the measles virus for the first time, and who has not been immunised, will develop measles, whereas only some people who smoke, even heavily, will develop lung cancer. In the case of lung cancer, therefore, there must be other predisposing factors operating in addition to smoking.

For other diseases the concept of causation is even more complicated. In one sense the cause of a heart attack can often be identified as a blood clot that has formed in a coronary artery narrowed by the deposition of cholesterol and other substances, but that is only the proximate cause. All sorts of other predisposing causes may have operated in the past: high blood pressure and raised blood cholesterol levels for example. Still more remote causes may include lack of exercise, perhaps emotional stress, and -- once again -- smoking.

Another type of cause, one that is receiving much more attention today with the advent of "genetic engineering", is heredity. Some diseases are transmitted directly from one generation to the next -- for example, haemophilia. More often, what is transmitted is a liability to disease, which may then be triggered by things in the environment. It is difficult to read the newspapers, listen to the radio, or watch television without hearing something almost daily about genetics as a cause of disease. Often, our new understanding of genetics is represented as a scientific blessing; we are promised that there will soon be technological cures for all kinds of diseases. The converse of this happy thought is the idea that insurance companies will soon require a genetic profile from customers seeking life assurance.

Different levels of causation

In general, we can think of causation as having different levels. The lowest level is that of the mechanism that is giving rise to the patient's symptoms: blockage, pressure, impaired blood flow or whatever. But there is also a secondary level: that of the factors that have given rise to the disease. These may include all kinds of life-style factors and also the patient's heredity, and their influence may originate from many years in the past, perhaps even before the patient's birth. The one thing that unites all this analysis of causation is the concept of pathology, which is the scientific study of disease.

The science of pathology

Suppose a patient complains of a "pain in the stomach". The doctor has to decide, first, which organ is responsible; this is often both the most difficult and the most important question to answer. Next, what sort of process is causing the pain? Perhaps there is an obstruction of some kind. If so, what is causing the obstruction: a stone, a tumour, pressure from outside, spasm? Diagnosis is a matter of following clues and drawing inferences, narrowing down the possibilities as far as possible. The skills of a doctor thus have something in common with those of a detective.

Pathology is of various kinds. Anatomical pathology describes the changes in organs that are visible to the naked eye. Microscopic pathology describes the changes that are visible with the microscope. Chemical pathology describes the changes that are measured by laboratory tests. Molecular pathology, still quite a new branch of the subject, describes the changes in the structure of the molecules within the cells, including the genes.

The body as machine

Since the middle of the nineteenth century, if not longer, the trend towards thinking of the body as a very complicated machine, but a machine nonetheless, has been becoming ever stronger in medicine. Even psychiatry, for long the one exception to this, is today almost wholly mechanistic; modern psychiatry is pretty much a branch of neurology, and psychiatric disorders are thought of as brain diseases. And this trend has received a huge impetus from recent discoveries in genetics, which have shown that there is a mechanistic explanation for the most basic processes of life.

Alternative medicine has different ideas

A lot of the appeal of alternative medicine is based on its claim to have a different, more "holistic" vision, and alternative practitoners frequently single out mechanistic thinking as the huge blind spot that afflicts orthodox medicine. However, they cannot plausibly deny that the mechanistic approach has yielded enormous benefits. (They often do try to deny it, however.) The uncomfortable fact is that in many cases the mechanistic approach has triumphantly worked. Just to take one example among many possible: in how many Victorian novels do we read of some luckless child suffering the dreaded scarlet fever and hovering for days between life and death at the whim of the author? This was a literary cliché at the time, but one based in fact; many children died of scarlet fever. Penicillin now offers a cure.

The fact undeniably remains that there are still many common diseases and disorders, such as migraine, asthma, and various kinds of arthritis, whose causes are imperfectly understood and for which present treatment offers some degree of control but not a radical cure. If you develop asthma in middle age you've almost certainly got it for life. Then there are those nebulous disorders that are perhaps not diseases at all in the sense that cancer, say, is a disease; here I am thinking of "modern" plagues such as irritable bowel syndrome, premenstrual tension, and the chronic fatigue syndrome ("ME").

No doubt these were always with us. "ME" may be a recent diagnosis, but "neurasthenia", which was a common diagnosis in the 1920s and 1930s, had similar symptoms, while Victorian ladies frequently "went into a decline", again with quite similar symptoms. In the case of some of these disorders, not only do modern doctors not agree about the causes; they do not agree about the basic mechanisms -- what is happening inside the body of sufferers -- or even whether the disorders in question actually exist at all.

Make way for alternative medicine, whose practitioners do believe in these disorders and do know what causes them. Moreover, they promise to cure them. They also promise to cure many of those diseases, such as arthritis and asthma, that conventional medicine lacks a full and satisfactory answer for. They claim they can do all this because they know the real causes of disease.

The important thing to understand about the way alternative medical practitioners who are not medically qualified think about disease causation is that, unlike conventional doctors, they don't think pathologically. They are not concerned with the mechanisms of disease, which they regard as comparatively uninteresting. These mechanisms may exist, they say, but we need not get caught up in them. If we live correctly, eat correctly, and think correctly, we will not get ill. The natural state of humankind is health. It is an underlying presupposition -- an article of faith, if you will -- in alternative medicine that diseases cannot take hold unless something predisposes the person towards them. The catch-phrase here is "seed and soil".

Disease causation in alternative medicine

So what are the things that predispose us to disease? The main causes of disease according to alternative medicine are:

  1. Diet

  2. Stress

  3. Faulty ways of thinking and feeling

  4. Allergy

  5. Orthodox treament (allopathy)

  6. Miasms (in homeopathy)

  7. Environment

Quite a number of these things are of course also recognized as causes of disease within conventional medicine. What alternative medicine does is usually not so much to posit an entirely new type of cause, although this does happen, as to reinterpret the conventional idea or take it considerably further than orthodox medicine would allow.

I shall now discuss these ideas in more detail.

1. THE ROLE OF DIET

Diet is a central cause of disease for nearly all alternative practitioners, and this idea has taken firm root in the population as a whole; about half the patients who come to see me raise the question at some stage, and nearly all are interested in discussing what they eat. This is hardly surprising, for orthodox medicine, too, attaches a lot of importance to a healthy diet, especially in the prevention of coronary heart disease, and makes recommendations that are endorsed by Government. Alternative and orthodox medicine agree on the desirability of reducing animal fats, sugar, and salt, and increasing the intake of vitamins and minerals to prevent coronary artery disease, but for alternative medicine this is just the beginning.

Many other diseases are alleged to be treatable by diet. Diets exist to help control eczema, sinusitis, arthritis, colitis, multiple sclerosis -- almost any disease or symptom you like to think of, in fact. Hardly any of these diets is based on proper scientific assessments, and many seem to have been composed at the whim of the author; few have any discernible scientific basis. But this does not deter people from following them, often with extraordinary tenacity in spite of the unpalatability of some diets, their practical inconvenience, and even their manifest nutritional inadequacy. It is difficult to understand why this should be so, but possibly it is partly because we feel that changing our diet is something that lies wholly within our own control; it is something we can do.

Other things play a part in our enthusiasm for diets as well. Food and cooking customs have stronger emotional and cultural roots than almost any other human activity, perhaps stronger even than sex. The anthropologist Claude Levi-Strauss sees the cooking of food as a central theme in the development of human culture.

Because cooking can be thought of as a form of technological processing, the back-to-nature movement prefers to eat raw food as much as possible -- vegetarian, naturally, because vegetarianism, though not obligatory for a healthy diet, is said to be preferable for a number of reasons, moral, aesthetic, and nutritional. If people must eat meat, they should eat white meat such as chicken rather than red meat, and fish is better than chicken. Partly, no doubt, this is because even orthodox medical authorities say that too much red meat is undesirable, but Coward may be right ['The Whole Truth', pp. 141-143] in believing that red meat, because it contains blood, is thought of as 'too strong'.

Vitamins and other food substances

Another aspect of diet is the use of food supplements. Many people believe it is necessary to take vitamins, minerals, and other substances to make up perceived deficiencies in their diet. There is also a belief in what Coward calls "magical foods". These are substances, such as ginseng and "royal jelly", that are supposed to have the ability to confer health in a general, non-specific way.

Most alternative practitioners regard incorrect diet as at least a contributory factor in the majority of diseases. They may well be right about this, but the problem is that the dietary advice they give often has little basis in fact. Few alternative practitioners have any idea of the amount of research that is needed to back up advice of this kind. For example, there has been a lot of interest recently in the fact that people who eat a lot of vegetables and fruit are less likely to suffer cancer and heart disease.

Many surveys have shown this to be true, but what is it about the diet that is beneficial? A popular idea, among doctors as well as the general public, is that anti-oxidant vitamins are responsible. The theory is that these vitamins help to reduce the damage caused by free radicals. Beta carotene is supposed to be particularly valuable for this purpose and there has been a huge increase in sales of this substance as a result. Alas, it doesn't work.

Some food supplements can he harmful

A study has been carried out on doctors in the USA. They were followed up for an average of 12 years. During this time they took either 50 mg of beta carotene or a placebo. There was no benefit from it at all. In another study, more than 18000 people who smoked or had been exposed to asbestos dust, and were therefore at increased risk of lung cancer, were treated daily with beta carotene and retinyl palmitate (another anti- oxidant) or placebo for an average of four years. Here the results were even worse: the risk of lung cancer was found to be higher in those who were receiving the supplements, so the trial was brought to a premature close. The New England Journal of Medicine, which published these reports, remarks that there was little solid scientific reason to expect that beta carotene would have the beneficial effects claimed for it. The two trials "should send a clear message to the public, and the tens of millions of dollars spent annually on beta carotene supplements should now be diverted to more useful purposes."

The same issue of the Journal has another report which does partially support the idea that vitamin E in food protects against heart disease. Among more than 34,000 post-menopausal women, coronary heart disease occurred less frequently among those whose diet contained a lot of vitamin E; nuts are a particularly good source of vitamin E. However, taking vitamin E supplements did not decrease the risk of heart disease, and the present state of knowledge "gives no clear guidance to the public about the value of antioxidant-vitamin supplements." But this does not mean that diet has no relation to chronic disease.

Eating a lot of fruit, vegetables and grains lowers the death rate from heart disease and cancer considerably, but we don't know why. It may have nothing to do with antioxidant vitamins at all. Until we do know, it is futile and misleading to give people detailed instructions about what they should and should not be eating, yet this is frequently done by naturopaths.

2. STRESS

The original concept of "stress", as described by its originator Walter Cannon, was mainly concerned with environmental influences. Exposure to cold, for example, is a stress; so is exposure to heat or danger of various kinds. These things cause adaptive changes in animals and people and it is thought that these changes can eventually lead to disease.

For example, the stress theory of how high blood pressure is caused goes as follows. Repeated exposure to challenging situations stimulates us to produce a primitive 'fight or flight' reaction. Our blood pressure rises, our heart rate increases, the blood flow to our muscles increases while that to our intestines decreases: in short, we are prepared for action. But as a rule, in a modern urban society, no physical action is needed.

If we are cut up by another driver while in our car, or if we are reprimanded by our boss at work, we can't resort to physical violence, much though we might like to. The result is that the aggression is internalized; our blood pressure remains up for a long time, we may develop a gastric or duodenal ulcer, and so on, and if this sequence is repeated often enough the result may be permanent.

It is a persuasive theory, and may even be true. But it is difficult to prove, and possibly is misleading. The medical writer Richard Asher once played a trick on his readers to illustrate this point. He quoted a description from a medical text written in 1871, in which the eminent author explained how the stress of modern life was causing people to suffer from duodenal ulcers.

It all sounds rather convincing, and, reading it, one is mildly amused, and rather impressed, to find that someone was saying this kind of thing as early as that. If that's what life was like in 1871, you think, how much worse must things be today. Then Asher pulls the carpet from under our feet. He admits to having practised a deception; the article he was quoting wasn't really about duodenal ulcer at all, it was about general paresis -- syphilitic dementia, the true cause of which was unknown when the article was written. So much for the stress theory in this case.

(In fact, even the hitherto accepted wisdom that duodenal ulcers are due to stress must be revised. Modern research shows that most ulcers are caused by infection with a bacterium called Helicobacter pylori.)

In most people's minds, and in the minds of many alternative practitioners, stress is thought of in a very general way, to include pretty much any experience we don't wish to have. There has been an interesting shift in the way patients react to the idea that "stress" may cause their symptoms. Fifteen or twenty years ago they were often quite resistant to the idea, believing that they were being told, politely, that their symptoms were "all in their minds". Today, in contrast, they usually accept the suggestion at once and indeed often make it themselves. This change in attitude may in part stem from the increased acceptance of alternative medicine, in which stress is thought to be a very important cause of disease, including serious disease such as cancer.

3. FAULTY HABITS OF THINKING AND FEELING

Even within orthodox medicine, attempts have been made to link personality patterns with susceptibility to cancer and heart disease. These apparently show that the chances of surviving cancer are better for some kinds of people than for others; patients who simply accept the diagnosis fatalistically seem to do worse than those who 'fight' the disease energetically, and also (which is perhaps more surprising) worse than those who deny that they are ill at all. The validity of these conclusions has been questioned, however, and even if they are correct one could still interpret them differently. It is possible that patients who simply accept the diagnosis without resistance do so because they already know, at some subconscious level, that they won't recover.

Personality and cancer

It has also been claimed that it is possible to detect which kinds of people are most at risk of cancer many years before they actually acquire the disease. Cancer patients are supposed to be self-sacrificing individuals who for much of their lives have done what other people wanted rather than what they themselves wanted. They are therefore repressed and suppressed, full of unacknowledged anger. Heart disease, similarly, has been linked with personality.

Personality and heart disease

The "Type A" personality (impatient, time-conscious, obsessed with work) is thought to be particularly liable to heart attacks. Quite a lot of research seems to support these ideas, though what is not clear is whether modifying people's thinking (if it can be done) will reduce the liability. Perhaps having such a personality is rather like having red hair; red hair makes you liable to get skin cancer from sunlight, but dyeing your hair black would not diminish your liability.

The studies I refer to have been made by orthodox researchers, some of whom are eminent, so it is not surprising that they have been welcomed by many alternative practitioners, who have adopted them unquestioningly, even though they are by no means full accepted as valid within orthodox medicine. Rather similar pen portraits have been drawn of the kinds of people most liable to suffer from other serious chronic diseases such as rheumatoid arthritis and multiple sclerosis.

Susan Sontag's criticism

I must admit to finding this linking of personality with disease one of the least attractive ideas in alternative medicine. First, it may not be true; the evidence is still unclear, and if the history of medicine in general, and psychiatry in particular, is anything to go by it is likely to remain so for some time. Second, as Susan Sontag writes in 'Illness as Metaphor', although these portraits are presented sympathetically the kind of personality depicted is not the one most valued in the twentieth century. We may pity such people but we regard them as social failures. And, because they are different, we are enabled to feel comfortably superior to them. We are not repressed and frustrated, so we are not at risk of getting cancer.

It is bad enough to know you have got cancer (or cancer has got you) without having to feel that it has happened because you are psychologically and emotionally inadequate. Even if it is true, but especially if it is not true.

What is perhaps even worse is the idea that patients' attitudes to their cancer determine whether they will recover. It is sometimes said or implied that patients "ought" to adopt an aggressive approach to their disease, but does this mean that if you are not getting better it's because your desire to recover isn't strong enough? The result is inevitably unjstified feelings of guilt in both the patient and his or her relatives.

Quite apart from questions of humanity, there is a logical flaw in the argument. Even if it is true that patients who have a positive attitude to their illness are more likely to recover (and this is by no means definite), that does not necessarily mean that a positive attitude promotes recovery. It could equally well mean that patients who were destined to do well already knew this at some level of their being, while those who were going to do badly also had a premonition of it. In other words, which is cause and which effect?

4. ALLERGY IN ALTERNATIVE MEDICINE

Allergy: a difficult word, because it is used so widely and loosely, sometimes even figuratively ('I am allergic to him').

In orthodox medicine, 'allergy' has a fairly precise meaning. It refers to a particular type of antigen--antibody reaction. The commonest form of this is hayfever, in which the antigen is pollen; antibodies of a particular kind (IgE) are present on the linings of the nose and elsewhere and react with the pollen to give the familiar symptoms of sneezing, running nose, and itching eyes. But although alternative medicine certainly recognizes hayfever as allergic, when alternative medicine practitioners speak of allergies it is usually food they have in mind.

Orthodox medicine also recognizes the existence of food allergies. Some people have an immediate reaction to food which is usually easy to spot. Their lips swell, their mouth and tongue tingle, and blister-like swellings develop inside the cheeks; there may also be asthma and nettle rash. All these symptoms develop within ten minutes of eating the offending food and are certainly due to allergy. About 60 per cent of children with eczema develop symptoms in their skin and elsewhere in response to certain foods; many different foods are responsible in such cases, but eggs, citrus fruit, wheat, and milk are among the commonest offenders.

There are also reactions caused by food that are not due to allergy but are produced in other ways. In a certain number of patients with migraine the attacks are brought on by food, especially chocolate, cheese, and red wine, though this is less common than many people think. Some patients have enzyme deficiencies that interfere with digestion and can cause intolerance to certain foods; for example, 80 per cent of Africans and Asians are deficient in lactase. If they drink milk they experience bloating and diarrhoea. Some patients with the irritable bowel syndrome react adversely to certain foods, but this is not a true allergy; the bloating and discomfort experienced by such patients may be due to the action of bacteria in the intestine, which ferment the food and produce gas and acid, thought this is speculative.

Skin tests for allergy, though fairly satisfactory for hay fever, don't work well for food allergy, and there are no really satisfactory laboratory tests either. The RAST (radioallergoabsorbent test) is only moderately helpful, and optimistic attempts to detect food allergies by mixing samples of the patient's blood with various foods (cytotoxic testing), by hair analysis, or 'iridology' (see below) are hopeless -- cargo cult science, in fact. There is no satisfactory method of confirming the diagnosis except to get the patient to take a strictly controlled diet (elemental diet) for two to four weeks and see whether the symptoms improve, but this is not something to do lightly; it is easy to mistake a psychological improvement due to suggestion for an improvement due to the diet, and diets of this degree of severity are not safe to maintain for any length of time and are not safe at all for children.

The role of suggestion

It is of course the suggestion factor that bedevils the whole question of food allergy. Thanks to an enormous amount of publicity, many people, including many alternative practitioners, are firmly convinced that their miseries are caused by food, especially the dreaded 'E numbers'. Some unfortunates have dedicated their lives to this idea and have become victims of the so-called 'total allergy syndrome'. They are said to be 'allergic to the twentieth century'. Some have lost their families, their jobs, and their money in consequence and a few have committed suicide. Such extremes are luckily rare, but many patients are victims of this delusion in a less catastrophic form. We are told on dubious evidence that food sensitivity is a common cause of headache, insomnia, tinnitus, palpitations, breathlessness, ankle swelling, abdominal bloating, and fatigue; in children it is supposed to cause hyperactivity, bed-wetting, and poor school performance.

The delusive nature of much of the food allergy idea has emerged clearly from several recent studies. In a recent survey in Buckinghamshire, in which over 18,000 people took part, over 4,000 claimed to have adverse reactions of kind or another to foods, food additives, or aspirin. Reactions to food additives were reported by 7.4 per cent of the responders, but when they were tested objectively only three people were found to be affected.

Another investigation was carried out in Manchester a few years ago. Twenty-two patients attending an allergy clinic for suspected food intolerance were assessed by a psychiatrist, after which they were tested for food intolerance with exclusion diets and by being given the suspected foods 'double- blind'; that is, with neither the patient nor the tester knowing whether they were receiving the food or a placebo.

Only four of the patients had definite evidence of food intolerance and all four were psychologically normal. Of the 18 in whom food intolerance was not confirmed, only one was found to be normal psychiatrically; ten of the remainder were depressed, and the others were thought to suffer from other kinds of psychiatric disorder. The group in whom food allergy was not confirmed was then compared with another group of patients who did not complain of food allergy but who had been referred to a general psychiatric clinic. The two groups turned out to be exactly the same in respect of their symptoms and psychiatric abnormalities. However, there was one significant way in which they differed: social class. The psychiatrically abnormal group whose members believed that they were allergic to food was composed predominantly of professional people.

Clinical ecology?

In the United States, and to some extent in Britain and other countries too, interest in the question of food allergies has led to the development of a form of treatment often called clinical ecology. Extracts of what are thought to be the offending foods are injected into or under the skin; if the patient is indeed sensitive to the food, the relevant symptom (wheezing, headache, or tinnitus, for example) occurs within a few minutes. The clinical ecologist can then stop the reaction by giving a different, 'neutralizing', dose of the same substance. Clinical ecology is practised both by doctors and by therapists who are not medically qualified. It has attracted a great deal of criticism from within mainstream medicine, but until recently there was little objective evidence available to help one to make up one's mind. A short while ago, however, a study was carried out at the University of California which sheds a lot of light on the subject.

Several experienced clinical ecologists took part. They selected a total of 18 patients who they believed were undoubtedly sensitive to foods, on the basis of repeated injections with a variety of food extracts. The patients had known what they were receiving on these occasions; none of them had reacted when given control injections of what they knew to be just the diluent, without the food extract.

In the study they were retested with the same substances in the same office, with the same technician giving the injections as before; the only difference was that now they did not know when they were receiving the active injection and when they were receiving the control. The technician and the observer who was assessing the result were also ignorant of what was being injected on each occasion. The results were clear-cut. Various symptoms were indeed produced by the injections, but the patients correctly identified only 16 out of 60 active injections (27 per cent) as having provoked symptoms. They also thought that 44 out of 180 control injections (24 per cent) were active. There was no difference in the symptoms produced by active and control injections.

Seven patients who had produced symptoms were given neutralizing injections. In most of these cases, as it later turned out, the initial injection which had produced the symptoms had been a control one; but the neutralizing injections relieved these symptoms just as effectively as they did the 'real' symptoms provoked by active injections.

The conclusion of this study seems to be inescapable: although (or because) these clinical ecologists genuinely believed in the technique they were using, on the basis of their experience, the effects they were seeing were due to suggestion and not to the substances they were injecting.

5. ALLOPATHY

The term "allopathy" was coined by Samuel Hahnemann, the inventor of homeopathy, to denote the conventional medicine of his day. When a patient had, say, diarrhoea, a conventional doctor would give opium to control the symptom (allopathy, from the Greek "allos", meaning "other"); homoeopathy (Greek "homoios" = same), in contrast, would use a medicine capable of causing the same symptom, such as white arsenic (think of the death of Madam Bovary as described by Flaubert). Hahnemann believed firmly that allopathy could actually cause disease, and this idea is still held today by many kinds of alternative practitioner, not only by homoeopaths. It is therefore quite common for patients to be told to stop their conventional treatment, even when this treatment is essential.

The kinds of treatment most commonly blamed for causing disease are probably antibiotics and corticosteroids, though the list is often widened to include pretty well anything produced by the modern pharmaceutical industry, even essential hormonal replacements such as thyroid hormone. Concern with possible "side effects" of drugs is widespread today, and of course it has a real basis. Every effective drug has potential unwanted effects. But legitimate concern about these has led some patients, and many alternative therapists, to believe that all conventional treatment is inevitably dangerous and should never be used.

6. MIASMS

This term again, like so many in alternative medicine, originated with Hahnemann. He used it to explain chronic disease. Why do we suffer from asthma, arthritis, and the myriad other medical ills that afflict us? Because of miasms. What is a miasm? The word means something like "taint" or "impurity". Hahnemann did not invent it -- it was already in medical use in his day -- but he gave it a special meaning.

He described three miasms: syphilis, sycosis, and psora. Much the most important of these is psora. As described by Hahnemann, psora is really a kind of infection; it is transmitted by an infected person touching someone else's skin, typically at or soon after birth, and it remains latent in the body until, years later, it erupts to give pretty well any kind of disease you like to think of, from gout to cancer.

The first sign of psora is always a skin lesion of some kind, but it may be small and transient and so may not be noticed by the patient. Later there may be other skin manifestations -- rashes of various kinds, especially itchy ones, but these too disappear, to be followed years later by all kinds of chronic disease. There is an obvious similarity here to syphilis, which does indeed go through all these phases; in fact, if you want to understand how Hahnemann thought about psora, think of syphilis.

The obvious weakness of the theory is that it explains too much. If practically any disease or symptom you care to think of is due to psora, what would be an example of a disease that is not due to psora? It is almost impossible to suggest one. By trying to explain everything the psora theory succeeds in explaining nothing. This has however not prevented many later homoeopaths from adopting it. And, by a curious extension of the theory, later homoeopaths came to think of miasms as hereditary, even though Hahnemann had quite clearly postulated an acquired infection. Ultimately many homoeopaths came to think of psora as a kind of Original Sin.

The miasm theory as set forth by Hahnemann has not been taken up under that name by many alternative practitioners other than homoeopaths, but there are other supposed causes for disease in alternative medicine that are quite similar, in that they are based on supposed infections. A good example of this is the candida theory.

Candida albicans is a yeast that gives rise to thrush, a superficial infection of moist surfaces such as the vagina and, in babies, the mouth. It is in fact often present in the vagina without causing symptoms, but sometimes, for unknown reasons, it gives rise to discharge and itching; some women seem to be particularly susceptible to it. It is also found in the lower part of the bowel, where again it usually cause no problems. As a rule it is a nuisance rather than a threat to life, but in people whose immune system is damaged, perhaps by drugs given to suppress tumours, candida may spread inside the body, affecting many internal organs and leading eventually to death.

This much is well recognized in orthodox medicine. In alternative medicine, however, there has grown up a wide-spread belief that there is another set of symptoms due to candida overgrowth in the intestines. These include almost anything you like to name: fatigue, headache, listlessness, spots before the eyes, abdominal bloating, looseness of the bowels... the list goes on and on.

The reason for the overgrowth of candida is supposed to be the use of antibiotics (all the fault of conventional medicine again, you see). A recognized unwanted effect of some antibiotics (the so-called broad-spectrum group) is that they tend to alter the proportions of the bacteria that normally live in the lower part of the intestines, and in rare cases this can have serious or even fatal consequences.

The candida theory builds on this fact; if you have had a course of antibiotics in the past, especially a long one or a repeated series of courses, this is said to make you vulnerable to candida. The trouble with the candida theory, as with most theories of this kind, is that it is very hard to assess objectively.

Candida certainly does exist in the gut, but it is difficult to say at what point it becomes abnormal in quantity. It is still more difficult to explain how candida could give rise to the remarkable range of symptoms that it is blamed for. But this comprehensiveness is of course just what recommends it to many patients and alternative therapists.

7. ENVIRONMENT

Both orthodox and complementary medicine accept the idea that the environment is an important cause of disease. We are constantly bombarded with the notion that we are surrounded by dangerous toxins, and there is usually the addition implication that this is an evil imposed on us by modern technology.

In fact, exposure to toxins is as old as civilization. The decline of the Roman Empire has even been blamed by some on the Romans' use of lead piping for their water supply, while in the Middle Ages populations were sometimes affected by ergot poisoning in their wheat stores.

Where alternative medicine differs from orthodox medicine is in the bizarre nature of some of the alleged toxins. "Geopathic stress", for example, is a feared environmental danger for some alternative practitioners. This will seem fairly fantastic to most people, but in other cases the boundary between real and imagined threats is harder to draw.

For example, there have been a number of studies that seem to show that living close to electric power lines is dangerous, at least for children; there are reports of an association with childhood leukaemia. The difficulty here is that the association is statistical; and the electricity companies naturally dispute it.

If such an association does exist, how might it work? One recent idea is that the electric field somehow concentrates the environmental radon. (Radon is a radioactive gas, exposure to which has been linked with cancer. Its concentration varies from place to place, being higher in areas where there is a lot of granite.) This might provide a plausible mechanism for the association between electricity and childhood leukaemia, if indeed this is real; but not all experts are convinced.

Conclusion

Looking over this list of causes of disease, we can see that those offered by alternative practitioners are fairly easy to understand. This is one reason for their appeal: they make sense on a human level.

The kinds of explanation that orthodox medicine provides, in contrast, are difficult to understand. Doctors notoriously use jaw-breaking words derived from Latin or Greek, and they tend to do this even when a perfectly good English word exists. But quite apart from the vocabulary, the ideas themselves are difficult to grasp; indeed, many doctors, especially if it is some years since they qualified, are likely to have a rather shaky grasp of the details of modern immunology or molecular biology. And even if they do understand their subject well, it doesn't follow that they will be able to explain it clearly to their patients; the art of popularizing science is not possessed by everyone.

Moreover, many people leave school with little or no grasp of even elementary science; it can therefore be very difficult to convey even quite basic items of information to them. In consequence, there is a tendency for doctors to sound either incomprehensible or condescending. Alternative practitioners, on the whole, don't run into these difficulties. The concepts they operate with are much the same as their patients', and in addition the alternative practitioners, as we have seen, are often better at communicating with patients anyway.