in Specific psychiatric disorders

What is schizophrenia?

“What is Schizophrenia?”

Someone asked me this at a party recently. It’s a difficult question to answer in a single sentence.

For a start, schizophrenia is not a single disorder. According to the ICD-10 it is a group of disorders, classified under F20 in a chapter called ‘Schizophrenia, schizotypal and delusional disorders’.

F20 is split into the following sub-classifications:

F20.0 Paranoid schizophrenia

F20.1 Hebephrenic schizophrenic schizophrenia

F20.2 Catatonic schizophrenic schizophrenia

F20.3 Undifferentiated schizophrenia

F20.4 Post-schizophrenia depression

F20.5 Residual schizophrenia

F20.6 Simple schizophrenia

F20.8 Other schizophrenia

F20.9 Schizophrenia, unspecified

(I can’t immediately find out what happened to F20.7 – maybe it suffered the same fate as floor number 13 in New York skyscrapers)

The aetiology of schizophrenia is unknown; as this is the case we are forced to define schizophrenia on the basis of a number of symptoms which appear together sufficiently frequently to merit a grouping. In this way schizophrenia is a syndrome rather than a disease. A disease is a disorder with a specific cause and recognizable signs and symptoms whereas a syndrome is combination of signs and/or symptoms that form a distinct clinical picture. The ICD-10 classification system deliberately avoids including aetiology in its definition.

Schizophrenia is a disorder which covers a wide range of cognitive, emotional and behavioural disturbances; there is disintegration in the process of thinking, of contact with reality and a pattern of emotional unresponsiveness.

ICD-10 puts it nicely:

The schizophrenia disorders are characterized in general by fundamental and characteristic distortions of thinking and perception and by inappropriate or blunted affect.

There is no one sign that ‘guarantees’ a diagnosis of schizophrenia. For instance many of the characteristic symptoms of schizophrenia can occur during a manic phase of bipolar disorder or during psychotic depression. However the following ‘fundamental and characteristic disorders of thinking and perception’ are considered to have special importance in the diagnosis of schizophrenia. They are based on Schneider’s first rank symptoms, proposed in 1959 and are:

a) thought echo, thought insertion or withdrawal, and thought broadcasting;

(b) delusions of control, influence, or passivity, clearly referred to body or limb movements or specific thoughts, actions, or sensations; delusional perception;

(c) hallucinatory voices giving a running commentary on the patient’s behaviour, or discussing the patient among themselves, or other types of hallucinatory voices coming from some part of the body;

(d) persistent delusions of other kinds that are culturally inappropriate and completely impossible, such as religious or political identity, or superhuman powers and abilities (e.g. being able to control the weather, or being in communication with aliens from another world);

(e) persistent hallucinations in any modality, when accompanied either by fleeting or half-formed delusions without clear affective content, or by persistent over-valued ideas, or when occurring every day for weeks or months on end;

(f) breaks or interpolations in the train of thought, resulting in incoherence or irrelevant speech, or neologisms;

(g) catatonic behaviour, such as excitement, posturing, or waxy flexibility, negativism, mutism, and stupor;

(h) “negative” symptoms such as marked apathy, paucity of speech, and blunting or incongruity of emotional responses, usually resulting in social withdrawal and lowering of social performance; it must be clear that these are not due to depression or to neuroleptic medication;

(i) a significant and consistent change in the overall quality of some aspects of personal behaviour, manifest as loss of interest, aimlessness, idleness, a self-absorbed attitude, and social withdrawal.

(Source of (a)-(i) ICD-10)

The final thing to say is that the conception of schizophrenia is to a certain extent historical and many textbooks choose to explain schizophrenia as a disorder with reference to the history of its classification. The term itself was Bleuler introduced the term in his 1911 book ‘Dementia praecox or the group of schizophrenias’

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  1. My son was diagnosed with undifferentiated schizophrenia. I was told he has symptoms of several different types of schizophrenia. Is that what undifferentiated means?

  2. Here’s the ICD-10 criteria for ‘Undifferentiated Schizophrenia’

    Psychotic conditions meeting the general diagnostic criteria for schizophrenia but not conforming to any of the subtypes in F20.0-F20.2, or exhibiting the features of more than one of them without a clear predominance of a particular set of diagnostic characteristics.

    This would seem to chime with what you say. If you’d like to know more about the different types of schizophrenia then go to this link

  3. Hey Paul,

    Okay, in retrospect, this is rather a bland uncritical posting. In fairness to me I was trying to present a definition of schizophrenia as a lot of mental health professionals would choose to classify it i.e. by using ICD-10 criteria. If you were a psychiatrist and choose to make a diagnosis of schizophrenia on this basis then a jury of your professional peers (which seems to be the criteria used for identifying lapses of medical judgement) would have little room to criticize you.

    Hand on heart I like to write more in-depth that the above post and I think that it is missing a discussion of how useful this label/diagnosis is, whether schizophrenia is a category or a dimension and the use of a medical diagnosis at all. Renaming schizophrenia as Striatal Dopamine Dysregulation or similar, as Robin Murray has suggested is also interesting. However I’ve just changed jobs and my free time has plummeted so I thought that I’d write something short and if a visitor to this site knew nothing about the subject, the ICD definition isn’t a terrible place to start.

    I had a tutor last year who like to say that if you’re learning about psychiatry then you should be careful not to try to rewrite the classification system at the same time. This does not mean that an uncritical eye is unnecessary, but is a tacit recognition that classification in mental health is difficult.

    Thanks for your links, they are always very interesting. I’ve been considering whether to try and bullshit you on this one, but I can’t say I’m sure what a logical positivist scientific perspective is. Social constructive I’m better on, and with this in mind, I was going to mention schizophrenia’s reported universal 1% prevalence across cultures. But this I thought might make a post in itself, so left it for another day….

  4. Although Xiang’s study this year of 5926 people found the prevalence of schizophrenia, in a decent study, to be 0.39% in rural areas, 0.57% in urban areas and 0.49% overall. Goldner, 6 years ago, had a slightly higher prevalence rate of 0.55%, when I were a lad I was taught it was 0.85%.

    Just to say, overall, true schizophrenia probably is substantially less prevalent than 1% of the population, no?

  5. Well, according to my Manchester Course revision notes the prevalence is c1% and they state this paper by Kendler et at as evidence. Kendler finds that by computer algorithm lifetime prevalences of narrowly and broadly defined psychotic illness were 1.3% and 2.2%. This dropped to 0.2% and 0.7% by clinician diagnosis.

    Birmingham notes state:

    By combining data an overall estimate of lifetime risk is between 0.5-1.6% often quoted as 1%

    They also say that this book by Robins and Reiger states the lifetime risk is 1.3%.

  6. Hi Frontier,

    Re classification

    I’ve no problem with classification per se, but the schizophrenia taxon was discredited years ago (see work by nosologist and psychiatrist Prof Ian Brockington for example). I agree the ICD and DSM descriptions carry great weight but they are certainly far from uncontroversial. What’s more, they lead to unjustified anxiety, pessimism and hopelessness in often terrified young people.

    Re positivism

    I think logical positivism was a movement which influenced the ‘received view’ in science. Bem & Looren de Jong (2006) in their ‘Theoretical Issues in Psychology’ offer a description of the basic philosophy:

    “Science consists of statements describing positive objective facts, plus logical relations between these statements”

    Orthodox psychiatry (especially biological psychiatry) often seems to subscribe to some of the basic tenets which can lead to the vision of a psychiatrist making objective clinical assessments of their patient’s ‘disorders’. It can be hard to reconcile with talk of such things like values, ethics, subjectivity, power etc etc.

    Re prevalence

    I think prevalence of the schizophrenia diagnosis may be a lot lower but much much more variable than traditional WHO estimates. See a discussion by your new President:

    “Of the 132 core studies, 21 studies reported point prevalence, 34 reported period prevalence, and 24 reported lifetime prevalence. The median prevalence of schizophrenia was 4.6/1,000 for point prevalence, 3.3/1,000 for period prevalence, 4.0 for lifetime prevalence, and 7.2 for lifetime morbid risk.”

    Best, Paul

  7. P.s. the universal 1% prevalence is blown out of the water by the paper Bhugra discusses in the link above. This isn’t really surprising if you adopt the view that while trauma, unusual experiences and ‘false’ beliefs are no doubt rife across time and culture, it’s how you make sense of it that matters when it comes to distress, help-seeking and impaired decision-making capacity.

  8. I also don’t know more about the topic, can anybody give me more information about the topic.



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  9. Thanks so much for your post, and your blog. Millions of Americans suffer from a misdiagnosed or undiagnosed mental illness. Silver Hill Hospital has clinicians trained in evaluation, diagnosis and adult and adolescent psychiatric treatment and provides hope for people who may not have been getting the right care. Talking/blogging about mental illness can be extremely helpful not just for yourself, but for others in need. Keep up the good work.

  10. Re ‘what happened to F20.7’

    Isn’t it just that xx.8 is always ‘other’ and xx.9 is always ‘unspecified’, e.g. tic disorders jumps from 95.2 to 95.8 …

    Perhaps you were just joking, but just thought I’d chip in in case people weren’t aware…

    Nice site btw