Valuing the unusual illness debate:

May 28, 2009  "Mind Hacks"

Valuing the unusual illness debate:

One of the particular joys of psychiatry is the regular ritual where a small but determined group of researchers try and get their idea for a new diagnosis accepted into the DSM. The most recent outbreak has hit the LA Times where a short article notes the proposal for 'posttraumatic embitterment disorder'.

The idea for the disorder, where people are impaired by feelings of bitterness after "a severe and negative life event", is not new. A small group of German researchers have been proposing the disorder in the medical literature since 2003 and have recently released a psychometric scale which they argue can diagnose the condition.

The last incarnation of this debate to hit the mainstream press was discussion over whether extreme racism could or should be diagnosed as 'racist personality disorder'.

The discussions are interesting because they cut to the heart of how we define an illness. This is usually discussed as if it is a problem specific to psychiatry, as if diagnoses in other areas of medicine are more obvious, but this is not the case.

Implicit in medical diagnoses is the concept that the change or difference in the person has a negative impact.

Importantly, the biological 'facts' have little to do with this, because whether something has a 'negative impact' is largely a value judgement.

An infectious disease is not defined solely on the basis that it is a bacteria or virus, as we have many bacteria or viruses in our bodies that cause no problems. It's only when they cause us distress or impairment that they're classified as an illness.

In fact, there are some bacteria or viruses that are completely harmless in certain areas of the body, but cause problems in others. Like in cases of viral encephalitis where otherwise benign viruses can cause problems when they get into brain tissue.

In some cases the definition is partly based on a comparison to what's average for a person of this type. Differences in brain structure, such as some white matter lesions, may be considered medical problems in young people but normal in older people.

But there are many human characteristics that we could equally classify as being 'not normal' and 'negative' but we don't currently accept as illnesses.

Being left-handed is clearly a statistical deviation from the average, has been associated with a greater risk of breast cancer, an increase in accidental injuries, and has been genetically linked to schizophrenia. But left-handedness is not considered an illness.

In other words, there is no definition of an illness which is divorced from a subjective interpretation of what counts as 'negative'.

We also have some subjective and fairly fuzzy cultural ideas just about what sort of things count as medical conditions and require attention from doctors. Someone born with a missing thumb - yes, someone born left-handed - no.

Many of these assumptions are not about the properties of the 'illness' but about what we think doctors should be doing and what we feel the place of medicine in society should be.

Psychiatric disorders are just another instance of this. So when you hear proposals for seemingly wacky mental illnesses, think to yourself, why is this not an illness?

Importantly, we should do the same for widely accepted mental illnesses, such as schizophrenia or depression. Ask yourself, on what basis is this an illness?

It's not that all new diagnoses are useful or all existing ones are nonsense, it's just that the process of questioning highlights our assumptions regarding the relationship between normality, human distress, impairment and the role of medicine in society.

Link to LA Times piece on bitterness as a mental illness.
Link to brilliant Stanford Philosophy Encyclopaedia entry on mental illness.

—Vaughan.