With about 86 billion neurons, the human brain is among our most complex and dynamic organs. It shapes our relationships and behavior, our perception of the world and ourselves. When any of these go wrong, we tend to locate the problem within our minds or brains, and thus within ourselves.
According to Harriet Fagerberg, the medical model, which construes mental ill health as a problem located within the individual, might be missing the forest for the trees. A postdoc with Justin Garson, Harriet joined the Biological Purpose Project in September of 2022. During her PhD, she worked at the intersection of psychiatry, medicine and philosophy at the Sowerby Philosophy in Medicine Project at King’s College London and the Berlin School of Mind and Brain at Humboldt-Universität zu Berlin.
In her previous work she dealt with the legacy of the outdated metaphor of mental illnesses as ‘software bugs’, separate from the hardware of the brain. In her current work she is trying to better understand how we should think of the notions of biological function and dysfunction, and their relation to mental and neurological disease.
So what is the current psychiatric model?
The psychiatric model is really an extension of the more general medical model. On the medical model, the way that you usually come to find out that you have a mental disorder is by being diagnosed by a clinician. Given the assumed theoretical framework in psychiatry, it is thus very strongly implied, or maybe even explicitly communicated, that a diagnosis means something has gone wrong inside you, and that bringing you back to mental health is a matter of fixing what's gone wrong.
An important premise of the medical model is thus that medical, including psychiatric, conditions are failures of the body to function as it should. Some theorists, for example Thomas Szasz, have questioned the extent to which the medical model fits psychiatry. On such a view, psychiatry mistakenly labels nonmedical forms of adversity, or ‘problems in living’, as legitimate diseases or medical problems.
This is an important context for the work we do as part of our project. We believe that getting the notions of function and dysfunction right will contribute to resolving this historical tension in psychiatry.
What are the different ways of seeing brain function?
A lot of people – in philosophy, but also in biology – loosely use the term function to pick out any effect of a chain of naturally selected effects. When the heart pumps it contributes to circulating blood around the body, supplies tissues with oxygen, and thus contributes to keeping the organism alive, but which one is the heart’s function? Some people say they are all the heart's function.
However, Justin and I believe that technically it is only the trait’s most proximal selected effect which is its function. In the case of the heart, the effect most proximate or specific to the heart is blood pumping. Our view is that it's technically inaccurate to say that circulating blood or contributing to fitness are functions of the heart. Circulating blood is in fact a more distal function of a larger, more complex system that includes the heart – that is, the circulatory system.
This might sound like kind of a fine point, but we believe it is important, because a dysfunction occurs when a trait fails to perform its function. There might be situations in which circulation is failing without the heart being dysfunctional - for example, when a clot in an artery inhibits blood circulation. However, the heart is not dysfunctional in such as case - something else went wrong which interrupted the casual chain.
We believe that dysfunction necessitates failure of proximate function. We think this is important for psychiatry, because we think there could be many cases where, on the face of things, it looks as if the brain or some part thereof is not functioning as it should. However, when you factor in that proper function are proximate functions, you will find there are lots of ways in which the brain can function strangely, unusually, or not ideally without really being dysfunctional. This opens up the possibility that many recognised mental disorders fail to involve dysfunction. If so, then the applicability of the medical model for psychiatry is again in doubt.
What are the practical implications of viewing proper functions as proximal functions?
One possible implication of the dysfunction-model of mental illness is that those diagnosed with mental disorders are told that the problem is located within them, thus directing attention away from the environment and towards the dysfunctional brain process within the individual.
When medicine tells us there’s something wrong inside us, it moves the focus away from fixing the situation or the environment towards fixing the organism. This can be a problem when the impact on functioning is really due to environmental circumstances, and when these circumstances would in fact be the best place to intervene.
An alternative explanation for why things are going badly for someone, beyond positing an internal dysfunction, is that something's going wrong in that person’s life. When an organism is in an inappropriate environment, things can go badly for them, and they might not be operating in a way that's maximally advantageous to them. But that doesn't necessarily mean that something is dysfunctional; it could be that the person, or the organism, is functioning as well as can be expected given a bad or unsuitable environment. Thus, the dysfunction-model may serve to distract us from the true sources of mental suffering.
What are you thinking about now?
Recently, I’ve gone full circle, and am back to thinking about the hardware-software analogy and its application in thinking about mental disorders. In previous research, I sought to undermine that model for thinking about mental illness, as I believe it rests on a false and misleading analogy.
However, I do think there are important differences between paradigm psychiatric illnesses and paradigm neurological illnesses. One assumption in medical science and research is that if something goes wrong at a higher level, then you should be able to trace it down to some smaller part having gone wrong. This seems to me an important but overlooked issue in the philosophy of biology: does dysfunction of the whole necessitate dysfunction of a part?
In particular, I’m interested in the extent to which brain function conforms to this picture. Maybe there are high level brain dysfunctions that aren't reducible to things going wrong at a lower level, as a consequence of the special plasticity of neural functions relative to other bodily functions. Perhaps there are ways in which the brain ‘goes wrong’ that have no analogy in the rest of the body, and which challenges the reductionist paradigm implicit in the medical model. These are some questions that I’m thinking about at the moment, and hoping to write something about it soon.