The Diagnostic and Statistical Manual (DSM) Edition V is in the limelight again. This new version of the American Psychological Association’s dictionary of mental illnesses is being released on May 18th. In the build up to this the National Institute of Mental Health (NIMH) have released a statement announcing their intention to move away from the DSM diagnostic criteria.

The NIMH say they want to encourage research which is less focussed on comparing different DSM diagnoses and more interested in exploring features or experiences which might be involved across several diagnoses. The experience of anhedonia, for example, which means loss of pleasure, might be felt by people with a range of different diagnostic labels. The NIMH say that they want to encourage studies which look for biological markers of some of these experiences. They unfavourably compare our knowledge about the biological markers of mental illness with our knowledge of the biological markers of physical illness. They suggest that our understanding has been hampered by trying too hard to link biological markers to the DSM diagnostic clusters.

Despite the controversy around the NIMH statement, discussions about viewing mental illness more on a continuum of experiences and less in terms of diagnostic boxes are not new. Foucault’s ‘Madness and Civilisation’ highlighted the tendency to treat people with a mental illness as different to ourselves. Instead of seeing mental illness and health as a dichotomy, we could view depression as profound sadness, for example. Similarly, psychosis is maybe not so far away from the feeling that someone is talking about you at the bus stop. The World Health Organisation equivalent of the DSM, the International Classification of Diseases (ICD-10), does in fairness take a slightly more descriptive approach to symptomotology, although still uses diagnostic classifications as a clinical short-hand.

The NIMH renouncing of the DSM has interested many anti-psychiatry movements, who view it as a shift away from medical models of mental distress. In my mind it is not a move away from medical models of mental illness, but a shift to looking at a familiar problem from a different level of explanation.

The NIMH have said they want to have a more robust biological understanding of mental illness. The emphasis on genes or neurotransmitters implies a hope that at some point we might be able to have a blood test for depression, or a brain scan for paranoia. To me, these two levels of description just seem to come at the problem from different points of view. Saying that you have the subjective experience of hopelessness and sadness and that you can’t get out of bed in the morning versus being able to say something like “my reward system circuitry is malfunctioning” could describe the same phenomenon, from two different perspectives. The quest for a biological marker suggests a dualistic mind-body view, and a suspicion that the biological is causal.

If this view were definitely true, then if we fix whatever is ‘wrong’ in our brain we will be able to get rid of the difficult psychological experience. But our brain chemistry changes in response to life events and we know that talking therapies act to alter our brains as as well as drugs. Our brain chemistry is altered, we think in different ways, we feel happier: all these things may be true at once, but it is not necessarily the biological that is altered first or only.

To take another example, the experience of falling in love: I could say my oxytocin and serotonin levels are changing, or I could say I feel romantically attached. Do they not both describe the same phenomenon in different ways?

This is not to say that understanding more about the genetic vulnerabilities and physical correlates for mental illness aren’t important. Clearly these are valuable areas of research. But to presume we are going to find a physical ‘thing’ that has gone wrong risks over-simplifying. If we take the battery out of a radio, for example, it will stop producing noise, but the battery is not the thing that makes the noise, it is part of a system that makes the noise happen. Our brains are so complicated that it is unlikely we are going to find one physical biomarker which diagnoses and explains a human experience like sadness. And in mental health it is the subjective human experience which is most important: extremes of human emotion which become unbearable for a person to cope with alone or which interfere with how they are able to interact with the world around them. We might be genetically more or less likely to experience the extremes of these human emotions, but experiencing them is also massively linked to life events of loss, change and adversity.

It’s great that the NIMH are challenging the DSM on their rigid categories and adding to discussions about more dimensional ways of viewing mental experiences, but let’s be careful not to try to aim for a similarly rigid physical classification. I’d hate to imagine that we were heading for a world where someone could be told their subjective experience of sadness was invalid because the physical markers weren’t there.