Saturday, March 21, 2020

The aetiology of mental disorder

I am grateful to Awais Aftab for his blog post, which follows our twitter conversation, I think after publication of my editorial. The same twitter conversation led to my last post.

Awais asks what is meant by 'functional mental disorder', even though he doesn't like the term because, he says, it is "too conceptually muddled". Nonetheless, he does seem to accept the validity of the term because he agrees some mental disorders will not "turn out to be the result of a cerebral disease". In fact, he says the majority will not.

Awais quotes a phrase that I commonly use: "mental disorders show through the brain but not necessarily in the brain". To be clear, it was not me that originated this phrase; it was Adolf Meyer. I do not think he used the phrase in any of his publications, but I came across it in his papers some years ago (see my book chapter). The actual phrase Meyer used was "All person disorders must show through the brain but not always in the brain [his emphasis]". As far as I am aware, there are no other references to this phrase in the literature. Meyer's use of the term 'person disorder' rather than 'mental disorder' in the phrase may give a clue as to how this debate about the meaning of 'functional mental illness' could be taken forward. The reason there is no independently diagnosable cerebral or systemic disease is because the disorder needs to be understood by focusing on the person. Several modern critics of psychiatry, perhaps particularly clinical psychologists (see previous post), argue that it's been a mistake to see personal problems as illness. I don't always agree with them, but the point is that the reason they are objecting to seeing mental disorder as illness is because they want to focus on the person. The critics generally do not even want to pathologise personal problems.

For me, Awais focuses too much on the causes, as such, of mental health problems. In my examinations when I trained in psychiatry, I was asked for my formulation or assessment of a patient that I had interviewed. This formulation was discussed in terms of differential diagnosis and aetiology. Note the use of the term differential diagnosis. Those who criticise one-word psychiatric diagnosis need to realise that the inherent uncertainty about psychiatric diagnosis is generally accommodated by discussing the options for diagnosis, rather than a specific diagnosis. I do realise this is not always the case and psychiatrists often jump too quickly to a single-word diagnosis, reifying complex personal issues (see eg. previous post). But this is not how they are, or should be, taught (see eg. another previous post).

For the purpose of this post, though, what I want to concentrate on is the way I used the term 'aetiology'. This has a wider meaning than simply causal. For organic problems the causes are cerebral disease, which can be primary or secondary to a systemic illness, or resulting from an exogenous toxic agent, or due to physical withdrawal of an addictive substance. But for functional disorders, we can't talk about a physical cause in the same way. We can't prove, in the sense of natural scientific proof, what causes functional mental health problems. That doesn't mean that we shouldn't make an attempt to understand them. We should! When I was asked for my formulation, what the examiner was looking for was some sort of assessment of the origins of the person's mental health difficulties in the context of their life history and personal and social situation. But that's very different from blaming causal factors.

I agree with Awais that there is inevitable uncertainty about whether a presentation is organic or functional. I have seen a few cases, but not many, in my working life where an organic disorder has unfortunately been missed. In fact the tendency of doctors is more to be biased in the opposite direction and make errors in favour of a physical diagnosis (see my book chapter). And, even one of the most psychosocial of psychiatrists, Harry Stack Sullivan, believed that a particular form of deteriorated schizophrenia must be neurobiological in origin. In retrospect, he may have underestimated the effects of institutionalisation in such cases, but because such patients' behaviour and presentation may be so difficult to understand, the temptation is to think that the cause must be biological. I can see why this happens, and for example, I think explains why Kendler thinks that schizophrenia has more risk factors in the biological arena than major depression or alcohol dependence (see previous post). But, paraphrasing Meyer, we need to guard against supposing a disease behind the functional presentation merely as a self-protective measure because of an insufficient knowledge of causal factors (see previous post). I can't prove a negative in the way Awais wants me to. Trouble is that he has the advantage because his view holds out the possibility of certainty (see my book chapter). My view can be just labelled as vague and woolly and dismissed for that reason, even though it may well be correct.

Awais seems to want to have it both ways by not saying whether depression is a functional or organic illness. This whole blog has been written against the misleading bias of biological psychiatry (of which Awais seems to be a part, even if at the more eclectic rather than radically reductionist end of that spectrum). In what sense can Awais really be said to be promoting the understanding of mental health problems? Knowledge of the brain may give no understanding of the person (see eg. BMJ letter).

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