In the previous post, I took issue with a TES article that opened with fidget-spinners and closed with describing dyslexia and ADHD as ‘crypto-pathologies’. Presumably as an analogy with cryptozoology – the study of animals that exist only in folklore. But dyslexia and ADHD are not the equivalent of bigfoot and unicorns.
To understand why, you have to unpack what’s involved in diagnosis.
diagnosis, diagnosis, diagnosis
Accurate diagnosis of health problems has always been a challenge because:
- Some disorders* are difficult to diagnose. A broken femur, Bell’s palsy or measles are easier to figure out than hypothyroidism, inflammatory bowel disease or Alzheimer’s.
- It’s often not clear what’s causing the disorder. Fortunately, you don’t have to know the immediate or root causes for successful treatment to be possible. Doctors have made the reasonable assumption that patients presenting with the same signs and symptoms§ are likely to have the same disorder.
Unfortunately, listing the signs and symptoms isn’t foolproof because;
- some disorders produce different signs and symptoms in different patients
- different disorders can have very similar signs and symptoms.
some of these disorders are not like the others…
To complicate the picture even further, some signs and symptoms are qualitatively different from the aches, pains, rashes or lumps that indicate disorders obviously located in the body; they involve thoughts, feelings and behaviours instead. Traditionally, human beings have been assumed to consist of a physical body and non-physical parts such as mind and spirit, which is why disorders of thoughts, feelings and behaviours were originally – and still are – described as mental disorders.
Doctors have always been aware that mind can affect body and vice versa. They’ve also long known that brain damage and disease can affect thoughts, feelings, behaviours and physical health. In the early 19th century, mental disorders were usually identified by key symptoms. The problem was that the symptoms of different disorders often overlapped. A German psychiatrist, Emil Kraepelin, proposed instead classifying mental disorders according to syndromes, or patterns of co-occurring signs and symptoms. Kraepelin hoped this approach would pave the way for finding the biological causes of disorders. (In 1906, Alois Alzheimer found the plaques that caused the dementia named after him, while he was working in Kraepelin’s lab.)
Kraepelin’s approach laid the foundations for two widely used modern classification systems for mental disorders; the Diagnostic and Statistical Manual of Mental Disorders, published by the American Psychiatric Association, currently in its 5th edition (DSM V), and the International Classification of Diseases Classification of Mental and Behavioural Disorders published by the World Health Organisation, currently in its 10th edition (ICD-10).
Kraepelin’s hopes for his classification system have yet to be realised. That’s mainly because the brain is a difficult organ to study. You can’t poke around in it without putting your patient at risk. It’s only in the last few decades that scanning techniques have enabled researchers to look more closely at the structure and function of the brain, and the scans require interpretation – brain imaging is still in its infancy.
you say medical, I say experiential
Kraepelin’s assumptions about distinctive patterns of signs and symptoms, and about their biological origins, were reasonable ones. His ideas, however, were almost the polar opposite to those of his famous contemporary, Sigmund Freud, who located the root causes of mental disorders in childhood experience. The debate has raged ever since. The dispute is due to the plasticity of the brain. Brains change in structure and function over time and several factors contribute to the changes;
- genes – determine underlying structure and function
- physical environment e.g. biochemistry, nutrients, toxins – affects structure and function
- experience – the brain processes information, and information changes the brain’s physical structure and biochemical function.
On one side of the debate is the medical model; in essence, it assumes that the causes of mental disorders are primarily biological, often due to a ‘chemical imbalance’. There’s evidence to support this view; medication can improve a patient’s symptoms. The problem with the medical model is that it tends to assume;
- a ‘norm’ for human thought, feelings and behaviours – disorders are seen as departures from that norm
- the cause of mental disorders is biochemical and the chemical ‘imbalance’ is identified (or not) through trial-and-error – errors can be catastrophic for the patient.
- the cause is located in the individual.
On the other side of the debate is what I’ll call the experiential model (often referred to as anti-psychiatry or critical psychiatry). In essence it assumes the causes of unwanted thoughts, feelings or behaviours are primarily experiential, often due to adverse experiences in childhood. The problem with that model is that it tends to assume;
- the root causes are experiential and not biochemical
- the causes are due to the individual’s response to adverse experiences
- first-hand reports of early adverse experiences are always reliable, which they’re not.
Kraepelin’s classification system wasn’t definitive – it couldn’t be, because no one knew what was causing the disorders. But it offered the best chance of identifying distinct mental health problems – and thence their causes and treatments. The disorders identified in Kraepelin’s system, the DSM and ICD, were – and most still are – merely labels given to clusters of co-occurring signs and symptoms. People showing a particular cluster are likely to share the same underlying biological causes, but that doesn’t mean they do share the same underlying causes or that the origin of the disorder is biological.
This is especially true for signs and symptoms that could have many causes. There could be any number of reasons for someone hallucinating, withdrawing, feeling depressed or anxious – or having difficulty learning to read or maintain attention. They might not have a medical ‘disorder’ as such. But you wouldn’t know that to read through the disorders listed in the DSM or ICD. They all look like bona fide, well-established medical conditions, not like labels for bunches of symptoms that sometimes co-occur and sometimes don’t, and that have a tendency to appear or disappear with each new edition of the classification system. That brings us to the so-called ‘crypto-pathologies’ referred to in the TES article.
Originally, terms like dyslexia were convenient and legitimate shorthand labels for specific clusters of signs or symptoms. Dyslexia means difficulty with reading, as distinct from alexia which means not being able to read at all; both problems can result from stroke or brain damage. Similarly, autism was originally a shorthand term for the withdrawn state that was one of the signs of schizophrenia – itself a label. Delusional parasitosis is also a descriptive label (the parasites being what’s delusional, not the itching).
What’s happened over time is that many of these labels have become reified – they’ve transformed from mere labels into disorders widely perceived as having an existence independent of the label. Note that I’m not saying the signs and symptoms don’t exist. There are definitely children who struggle with reading regardless of how they’ve been taught; with social interaction regardless of how they’ve been brought up; and with maintaining focus regardless of their environment. What I am saying is that there might be different causes, or multiple causes, for clusters of very similar signs and symptoms. Similar signs and symptoms don’t mean that everybody manifesting those signs and symptoms has the same underlying medical disorder – or even that they have a medical disorder at all.
The reification of labels has caused havoc for decades with research. If you’ve got a bunch of children with different causes for their problems with reading, but you don’t know what the different causes are so you lump all the children together according to their DSM label; or another bunch with different causes for their problems with social interaction but lump them all together; or a third bunch with different causes for their problems maintaining focus, but you lump them all together; you are not likely to find common causes in each group for the signs and symptoms. It’s this failure to find distinctive features at the group level that has been largely responsible for claims that dyslexia, autism or ADHD ‘don’t exist’, or that treatments that have evidently worked for some individuals must be spurious because they don’t work for other individuals or for the heterogeneous group as a whole.
Oddly, in his TES article, Tom refers to autism as an ‘identifiable condition’ but to dyslexia and ADHD as ‘crypto-pathologies’ even though the diagnostic status of autism in the DSM and ICD is on a par with that of ADHD, and with ‘specific learning disorder with impairment in reading‘ with dyslexia recognised as an alternative term (DSM), or ‘dyslexia and alexia‘ (ICD). Delusional parasitosis, despite having the same diagnostic status and a plausible biological mechanism for its existence, is dismissed as ‘a condition that never was’.
Tom is entitled to take a view on diagnosis, obviously. He’s right to point out that reading difficulties can be due to lack of robust instruction, and inattention can be due to the absence of clear routines. He’s right to dismiss faddish simplistic (but often costly) remedies. But the research is clear that children can have difficulties with reading due to auditory and/or visual processing impairments (search Google scholar for ‘dyslexia visual auditory’), that they can have difficulties maintaining attention due to low dopamine levels – exactly what Ritalin addresses (Iversen, 2006), or that they can experience intolerable itching that feels as if it’s caused by parasites.
But Tom doesn’t refer to the research, and despite provisos such as acknowledging that some children suffer from ‘real and grave difficulties’ he effectively dismisses some of those difficulties as crypto-pathologies and implies they can be fixed by robust teaching and clear routines – or that they are just imaginary. There’s a real risk, if the research is by-passed, of ‘robust teaching’ and ‘clear routines’ becoming the magic bullets and magic beans he rightly despises.
*Disorder implies a departure from the norm. At one time, it was assumed the norm for each species was an optimal set of characteristics. Now, the norm is statistically derived, based on 95% of the population.
§ Technically, symptoms are indicators of a disorder experienced only by the patient and signs are detectable by others. ‘Symptoms’ is often used to include both.
Iversen, L (2006). Speed, Ecstasy, Ritalin: The science of amphetamines. Oxford University Press.