Watch that metaphor!

Terms like ‘antidepressant’ and ‘antipsychotic’ are metaphors. They are analogies with ‘antibiotic’ which was the medical triumph of the 20th century. ‘Antipsychotics’ once were called ‘major tranquillizers’ or ‘neuroleptics’, and the encroaching ‘anti-’ terms replaced past metaphors and models by which psychiatrists made sense of the phenomena of madness and deviance.

The antibiotic metaphor calls up an idea of disease based on germs or germ-like pathological processes which are alien to the organism’s normal function. That metaphor now dominates our thinking about psychiatric illness and its treatment, displacing past moral and dynamic metaphors. You can see this idea of alien germ-like process in Emile Kraepelin’s writing (Kraepelin nominated the microbiologist Robert Koch for the Nobel Prize in 1905 (Nobelprize.org, 2015)). The germ metaphor came from behind in mid 20th century to overtake psychoanalytic and other metaphors. Clearly fashion changed (and intellectual fashion can feel like newly discovered truth).

Metaphors (which include analogies, similes and models) are cognitive tools by which something unknown is understood in terms of something known. Metaphors (models) are central in psychiatry. We fit observed phenomena (hallucination, sleep disturbance, etc.) to disease models and the models give the phenomena a meaning as pathology and distinguish relevant and significant phenomena from the irrelevant and insignificant (Rosenman, 2008). Centuries of epistemology have charted the limits of factual knowledge and of human understanding. While we can observe phenomena, we cannot observe what lies behind them (which belongs to the realm of concepts or understanding). We ‘understand’ in terms of models, metaphors and analogies (Leary, 1992). Models of disease are not observable facts, they are concepts that illuminate connections and co-occurrences between phenomena and guide treatment where aetiology and disease processes cannot be observed directly. To us, our models and diagnoses have the force of reality, but they are theories based on metaphor.

We have constructed the idea of most psychiatric illnesses in the model of an alien process afflicting a host, so treatment is to eradicate (remove by the root) that process. We look past the phenomena to our conceptual model of cause, and approach the treatment as we would approach anti-biotic treatment. That is, we delineate the alien pathogen or process and apply the appropriate specific ‘anti-’ medicine and increase the dose until it is eradicated.

The ideal antibiotic is lethal to the germ and harmless to the host. This has not held for actual antibiotics, so much less so for the metaphorically ‘anti-’ medications in psychiatry. By virtue of the antibiotic metaphor, we have tolerated and justified side-effects and ‘collateral’ harms to the health of patients some of whom now describe themselves as ‘survivors’ of psychiatric treatment.

The germ and antibiotic (specific disease/specific treatment) models are metaphoric models implicit in the ‘medical model’, and the power and prestige of that model has swept away critical dissent in the profession. However, dissent has now crept into the intellectual centre. The National Institute of Mental Health (NIMH) in the United States has abandoned Diagnostic and Statistical Manual of Mental Disorders (DSM) diagnoses as models for its funded research, calling the DSM an ‘epistemic prison’ (Greenberg, 2013) and apparently repudiated the American profession’s diagnostic beliefs and its ‘Bible’. The NIMH proposed replacing diagnostic models with models of ‘research domains’ which are five conceptual ‘domains’ of functional psychological ‘systems’ (negative and positive valence, cognition, arousal, social process). The NIMH underlined that diagnoses are not themselves objects or phenomena but are now obsolete conceptual models of the temporal, meaningful, and causal connections between phenomena. Those obsolete models continue to shape and distort descriptions and treatment of symptoms.

It is a mistake to limit ourselves to that triumphant model of specific disease and antibiotic-like treatment as if it were the paradigm of medicine. We don’t abandon medicine if we abandon that model. Medicine is not a single medical model, but a collection of models and metaphors which have different imperatives and implications. Take a model such as auto-immune disease. In auto-immune disease, the machinery of the immune system may well be functioning normally. What is pathological is its target or its intensity. It is not an alien process invading the body but the body’s own vital processes. Similarly, the phenomena seen in mental illness need not be alien to the normal mind but may be normal phenomena that are abnormal in their focus or intensity. (Virtually all the phenomena of mental illness are seen also in non-pathological forms in the ‘normal’ population and even cardinal phenomena of illness as diverse as hallucination and compulsion are seen in everyday human psychology [Johns and van Os, 2001].)

Treatment in auto-immune disorder suppresses vital immunological processes. Immuno-supression has dangers and consequences such as infection and cancer. Psychotropic medicines, in the main, suppress psychological processes. Neuroleptics suppress motivation and imagination and interfere with regulation of body shape and movement. Benzodiazepines suppress behavioural control and discrimination. Selective serotonin re-uptake inhibitors (SSRIs) suppress the erotic core. Suppression is essential to their effect, not a side-effect of their attack on a specific disease process. Suppression of psychological processes, however necessary, has consequences and the advantages and disadvantages of those suppressions have to be weighed at the outset and throughout treatment. Treatment choices and doses will be adjusted continuously according to the balance of harms, and there will be cases where the treatment will need be postponed or suspended when its harms outweigh its benefits. (The same considerations apply to psychological therapies.)

An immunologist who did not adjust treatment over the course of an auto-immune illness might be considered negligent. In psychiatry, neglect of harms often appears to be the rule especially in settings that most use the psychotropic treatments with greatest potential for harm. The acute phase of an illness might justify potentially harmful treatment. Those considerations change very quickly, yet treatment often does not, especially when treatment is initiated by a treatment guideline or by a ‘tertiary’ expert but continued by clinicians who feel they don’t have authority to change it. This is, in part, a consequence of the model of the specific and alien disease and specific treatment.

For many of our signature conditions, there are other medical metaphors and models that illuminate better. We do not have to abandon medicine or embrace strange metaphors from outside medicine.

The choice of model and metaphor has profound consequences in practice. The metaphor and model of a specific disease/specific treatment (like germ/antibiotic) has been especially powerful in medicine but has exhausted its usefulness in psychiatry as it has in many branches of medicine. It is time to reconsider it and the concepts of diagnosis and treatment that go with it.