Questioning ‘one in four’

The Guardian has an excellent article questioning the widely cited statistic that ’1 in 4′ people will have a mental illness at some point in their lives. The issue of how many people have or will have a mental illness raises two complex issues: how we define an illness and how we count them.

Defining an illness is a particularly tricky conceptual point and this is usually discussed as if it is an issue particular to psychiatry and psychology that doesn’t effect ‘physical medicine’ but it is actually a concern that is equally pressing in all types of poor health.

The most clear-cut definition of an illness is usually given as an infectious disease that can be diagnosed with a laboratory test. For example, you either have the bacteria or you don’t.

However, you will acquire lots of new bacteria that will continue to live in your body, some of which ’cause problems’ and others that don’t. So the decision rests not on the presence or absence of new bacteria, but on how we define what it means for one type to be ‘causing a problem’. This is the central point of all definitions of illness.

For example, when are changes in heart function enough for them to be considered ‘heart disease’? Perhaps we judge them on the basis of their knock-on effects, but this raises the issue of what consequences we think are serious, and when we should consider them serious enough to count. Death within weeks, clearly, death within two years, maybe, but is still this the case if it occurs in a 90 year-old?

The idea of a personal change ‘causing a problem’ is also influenced by culture as it relies on what we value as part of a fulfilling life.

In times gone past, physical differences that caused sexual problems might only have been considered an illness if they prevented someone from having children. A man who had children, wanted no more, but was unable to have recreational sex with his wife due to physical changes might be considered unlucky but not ill.

The idea of normal sexual function was different, and so the concept of abnormality and illness were also different.

The same applies to mental illness. What we consider an illness depends on what we take for being normal and what someone has the ‘right’ to expect from life.

The fact that the concept of depression as an illness has changed from only something that caused extreme disability (‘melancholy madness’) to something that prevents you from being content is likely due to the fact that, as a society, we have agreed that we have a right to expect that we enjoy our lives. There was no such expectation in the past.

The problem of correctly diagnosing an illness is a related problem. After we have decided on the definition of an illness, there is the issue of how reliably we can detect it – how we fit observations of the patient to the definition.

This is a significant issue for psychiatry, which largely relies on changes in behaviour and subjective mental states, but it also affects other medical specialities.

Contrary to popular belief, most ‘physical’ illness are not diagnosed with lab tests. As in psychiatry, while lab tests can help the process (by excluding other causes or confirming particular symptoms) the majority of diagnoses of all types are made by what is known as a ‘clinical diagnosis’.

This is no more than a subjective judgement by a doctor that the signs and symptoms of a patient amount to a particular illness.

For example, the diagnosis of rheumatoid arthritis depends on the doctor making a judgement that the mixture of subjectively reported symptoms by the patient and objective observations on the body amount to the condition.

The key test of whether an illness can be counted is how reliably this process can be completed – or, in other words, whether doctors consistently agree on whether patients have or don’t have the condition.

This is more of an issue for psychiatry because diagnosis relies more heavily on the patient’s subjective experience, but it is wrong to think that bodily observations are necessarily more reliable.

For example, the Babinski response is where the toes curl upward after the plantar reflex is tested by stroking the bottom of the foot. It is commonly used by neurologists to test for damage to the upper motor neurons but it is remarkably unreliable. In fact, neurologists agree on whether it is present at a far lower rate than would be acceptable for the diagnosis of a mental illness or psychiatric symptom.

The problem of reliably diagnosing a condition is relatively easy to overcome, however, as agreement is easy to test and refine. The problem of what we consider an illness is a deeper conceptual issue and this is the essence of the debates over how many people have a mental illness.

The ’1 in 4′ figures seems to have been mostly plucked out of the air. If this seems too high an estimate, you may be surprised to learn that studies on how many people qualify for a psychiatry diagnosis suggest it is too low.

There is actually no hard evidence for one in four ‚Äì or any other number ‚Äì because there’s never been any research looking at the overall lifetime rates of mental illness in Britain. The closest thing we’ve had is the Psychiatric Morbidity Survey, run by the Office of National Statistics. The latest survey, done in 2007, found a rate of about one in four, 23%, but this asked people whether they’d suffered symptoms in the past week (for most disorders).

We don’t know what the corresponding rate for lifetime illness is, although it must be higher. Several such studies have been done in other English speaking countries, however. The most recent major survey of the US population found an estimated lifetime rate of no less than 50.8%. Another study in Dunedin, New Zealand, found that more than 50% of the people there had suffered from mental illness at least once by the age of 32.

Psychiatry has a tendency for ‘diagnosis creep’ where unpleasant life problems are increasingly defined as medical disorders, partly due to pressure from drug companies who develop compounds that could genuinely help non-medical problems. The biggest market is the USA where most drugs are dispensed via insurance claims and insurance companies demand an official diagnosis to fund the drugs, hence, pressure to create new diagnoses from companies and distressed people.

Whenever someone criticises a diagnosis as being unhelpful a common response is to suggest the critic has no compassion for the people with the problem or that they are wanting to deny them help.

The most important issue is not whether people are suffering or whether there is help available to them, but whether medicine is the best way of understanding and assisting people.

Medicine has the potential to do great harm as well as great good and it is not an approach which should be used without seriously considering the risks and benefits, both in terms of the individual and in terms of how it shifts our society’s view of ourselves and the share of responsibility for dealing with personal problems.

So when you hear figures that suggest that ’1 in 4′ or ’50%’ of people will have a mental illness in their lifetime, question what this means. The figure is often used to try and destigmatise mental illness but the most powerful bit of The Guardian article shows that this is not necessary:

People who experience mental illness often face stigma and discrimination, and it’s right to oppose this. But stigma is wrong whether the rate of mental illness is one in four, or one in 400. We shouldn’t need statistics to remind us that mental illness happens to real people. By saying that mental health problems are nothing to be ashamed of because they’re common, one in four only serves to reinforce the assumption that there’s something basically shameful about being “abnormal”.

If you want more background on the ’1 in 4′ figure or discussion about how we understand what is mental illness and who has it, an excellent three part series on Neuroskeptic tackled exactly this point.

Link to ‘How true is the one-in-four mental health statistic?’
Parts one two and three of excellent Neuroskeptic series

6 Comments

  1. rita
    Posted April 24, 2010 at 8:51 pm | Permalink

    Ooooh, that’s a great post! Off to read the Neuroskeptic articles now…….

  2. Jennifer R. Ewing
    Posted April 25, 2010 at 3:21 am | Permalink

    In the US, there’s been a definite push towards “medicalizing” many things which wouldn’t have been considered “disorders” twenty years ago. I submit that “Oppositional Defiant Disorder” is just a fancy way of giving doctors carte blanche to dispense Ritalin to perfectly healthy children who have the bad manners to defy their parents when they become teenagers. I agree that it’s wrong to stigmatize genuine mental illness. I would also agree it’s wrong to create a “mental disorder” where none exists, either because of uncaring parents or greedy drug companies.

  3. Posted April 25, 2010 at 4:31 pm | Permalink

    If 50% of people have a “mental illness”
    in their lifetime, then that makes
    mental illness so broad as to be
    meaningless. It’s like lumping in cancer
    and a head cold in the same category.
    You put it very well: stigma shouldn’t
    attach to suffering whether it’s common
    or rare. And to lump it all in together
    doesn’t do anyone a good service. I
    think that there is something really
    wrong with the way that we are taught
    (or not taught) to deal with life’s
    problems and to help each other with it.
    Life sucks sometimes. It’s in the nature
    of physical existence and mortality to
    suck. It hurts physically and
    emotionally. But just as we teach our
    children to distinguish between a broken
    leg and a nasty scrape, we need to
    distinguish between feeling bad over a
    bad mark, feeling bad over the loss of
    a loved one, and feeling bad because
    everything seems to be a deep dark pit with no
    end even though nothing particularly
    bad has happened.

  4. Posted May 6, 2010 at 4:50 pm | Permalink

    Vaughan:
    I agree with most of the content in this post, especially:
    “Psychiatry has a tendency for “diagnosis creep” where unpleasant life problems are increasingly defined as medical disorders, partly due to pressure from drug companies…”
    Your discussion of the relative nature of physical illnesses and the reliability of their diagnosis is compelling, but I would take issue with your implicit assumption that mental illness is a reality on a par with physical illness.
    In my view a diagnosis is essentially an explanation. If I go to a physician and complain that I’m constantly exhausted and that my urine output seems reduced, he will test the creatinine level in my blood, and if it is above, say, 2.0, he will suggest a diagnosis of kidney failure. The diagnosis explains the symptoms, and provides suggestions for appropriate intervention. Of course, the diagnostic process in physical medicine is imperfect, but it is grounded on real science and is regularly updated in the light of new information. But the imperfections and incompleteness of regular medicine have no bearing on the so-called mental illnesses, which in my view are entirely spurious. What at one time were conceptualized as mental illnesses would now be better conceptualized as neurological problems or simply behavioral problems. Today the concept of mental illness has the same level of validity as the concept of witchcraft. They are both spurious explanations for phenomena for which better explanations have been available for decades.
    But whereas the witchcraft explanation has been superseded by science in western societies, the equally spurious mental illness explanation has gained ground, driven as it is by powerful moneyed interests.
    So, thanks again for a great post. Please keep writing.
    Philip Hickey
    http://behaviorismandmentalhealth.com/

  5. Posted May 7, 2010 at 5:21 am | Permalink

    The increase in the diagnosis of depression correlates with the tolerability and efficacy of drugs to treat depression. It is much more likely a primary care physician will diagnose depression if it is thought to be something they can treat. See my post on this http://drpullen.com/2010/04/20/depression-it-helps-when-the-treatment-is-not-worse-than-the-disease/

  6. wotzilla
    Posted October 17, 2010 at 2:27 pm | Permalink

    The medicalization of everyday life is a phenomenon that interests me enormously. I see it as a wider cultural issue, not merely as an isolated by-product of modernized health care. What is particularly noteworthy, in my view, is the dizzying speed with which psycho-medicalization has progressed from mental-illness-as-social-stigma to the relative normalization of mental disorders, and from there, it seems, to their absolute normalization, whereby psychiatric diagnoses are seen not only as completely without stigma but necessary for the individual’s very self-understanding. It seems that in our fragmented, socially atomized world, a psychiatric diagnose is rapidly becoming the last stable thing which to clutch at for personal identity.

    What is the acronym by which your clan is known? Is it AS, ADD or ADHD, or perhaps ODD? In the modern world, diagnostics has taken on the role of the totem in primitive societies. For many people, a psychiatric label functions as the hub around which they construct their sense of self. The enormous buzz surrounding ambiguous neuropsychiatric diagnoses, most notably Asperger’s Syndrome, perfectly illustrates not only the complete reversal of social attitudes towards mental disorders but the extent to which the concept of mental disorder has become obfuscated by the medicalization of personality. Mental disorders are seen as normal to the extent that they have entered the realm of identity politics.


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