The medical model of mental illness: we’re not convinced

A great systematic review has been published in this month’s British Journal of Psychiatry. It has the slightly less than tabloid-friendly title Biogenetic Explanations and Public Acceptance of Mental Illness: Systematic Review of Population Studies, but behind the dense title is a really useful and important piece of work.

Matthias Angermeyer and his colleagues examined 33 studies which looked at the public’s beliefs about the causes of mental illness, in order to find out whether there is a relationship between those beliefs and the degree of tolerance people show towards people with experience of mental illness. This is important, not least because the shape of anti-stigma education and campaigning is determined by the causal model on which it is based.

Historically, the dominant model for public anti-stigma campaigning has been built on the foundations of the biogenetic model of mental illness, in which it is assumed that mental illness comes about primarily as a result of biochemical or genetic deviations.

Anti-stigma efforts have led to simple messages being devised, which are designed to get people to leave their prejudices behind. Under the biogenetic model, the types of messages you end up with are ‘mental illness is an illness just like any other,’ and ‘mental illness is treated with medication’.

Angermeyer’s systematic review concludes that biogenetic explanations for mental illness are correlated with less tolerance of people with mental illness amongst the general public, and therefore, basing anti-stigma work on biogenetically based causal models is an inappropriate means of countering stigma.

if you stop and think about it, it’s no wonder that the public are unconvinced by messages like ‘mental illness is just like any other illness’

This is not at all surprising to me, and you if stop and think about it, it’s no wonder that the public are unconvinced by messages like ‘mental illness is just like any other illness’. The reality is that mental illness(es) are not very much like physical illness(es). We need only to think about the way mental and physical illnesses are diagnosed to realise this.

In general medicine, diagnosis typically proceeds through the identification of signs which indicate the presence of disease. In the case of diabetes, for example, it is possible to determine whether the patient has the condition by measuring their blood glucose level. The patient may have been experiencing symptoms such as feeling thirsty and tired. These symptoms, although they do indicate the possible presence of the illness are not sufficient for a diagnosis of diabetes – the physician relies upon the results of a blood test (a sign) to make a confident diagnosis.

Psychiatric diagnosis does not work like this. Although it is assumed that there is a biological dimension to mental illness, there are no definitive physical indicators of mental illnesses which categorically and objectively confirm the presence or absence of a mental disorder. It isn’t possible to determine, say through measuring their serotonin level, whether a person is suffering from depression; nor is it possible to diagnose psychosis through carrying out a blood test or x-ray. Instead, psychiatric diagnoses are made by way of observation or reporting of ‘symptoms,’ which are nearly always subjective judgements about what people say and do.

The truth is that, whilst it seems there may be some biological and genetic factors in mental illness, the science is not sufficiently advanced to be able to be clear about what they are and how they act. Not only that, but, to a much greater extent than with physical illness, the social and political dimensions in the construction of mental illness are controversial.

Therefore, oversimplified, biogenetically based anti-stigma initiatives are destined to fail because they don’t acknowledge or attend to the true complexity of mental illness. They do little to engage with people’s genuine uncertainty about why mental illnesses come about, and their legitimate fears about the sometimes worrying ways in which mental illnesses affect people’s behaviour.

One of the reasons why anti-stigma work has so far tended to insist on keeping biogenetic explanations at its heart may be to do with psychiatry’s need to assert its scientific credentials in line with other medical specialisms. I particularly applaud Matthias Angermeyer and his colleagues for drawing attention to this possibility in their concluding remarks. In asking whether the insistence on neuroscientific emphases in public education about mental illness is really in the interests of patients, they show a refreshing humility, which should be welcomed by psychiatrists, scientists, and patients.