Just like when a physician sees a patient and looks for signs of physical illness, when a psychiatrist meets a patient they are looking for signs of psychiatric illness. This is important because when people are suffering a deterioration in their mental health, they often describe similar experiences and these signs of mental illness are referred to as psychopathology. When different psychopathological signs are identified and grouped together they can lead to the formation of a psychiatric diagnosis.
One of the most interesting psychopathology signs is formal thought disorder (FTD) which refers to the sort of disorganised speech which is a manifestation of psychosis.
When people are describing a patient’s mental state they often write ‘no FTD’ when they wish to convey that the patient is coherent and can make themselves understood. It’s a little bit more subtle than that; if a patient is intoxicated or delirious they will be incoherent but they will not necessarily be thought disordered. Thought disorder refers to a particular set of language errors which are seen in psychosis.
The name is rather strange. Although it is called ‘formal thought disorder’ it actually refers to what a patient is saying. The name is historical as when disorders of speech due to psychiatric illness were first being described (Bleuler, amongst others, was important in this), it was felt that disorders of thought form (disorganised speech) and content (delusions) should be considered separately. Formal thought disorder therefore is a disorder of speech rather than content*.
Normal human thinking has three characteristics
1. Content: what is being thought about – this would include delusions and obsessional thoughts
Different elements of formal thought disorder have been described. With his early work, Bleuler considered FTD to be when there was a loosening of associations which lead to fragmentary ideas being connected illogically. This is seen clearly in the picture above. Confusingly though, there appears to be no consensus about exactly what can be included formal thought disorder; it appears that most people would now use the term ‘thought disorder’ which refers to both errors of form and stream. Content is still considered separately.
Disorder of stream of thought
Flight of ideas is when the content of speech moves quickly from one idea to another so that one train of thought is not carried to completion before another takes its place. The normal logical sequence of ideas is generally preserved although ideas may be linked by distracting cues in the surroundings and from distractions from the words that have been spoken. These verbal distractions may be of three kinds: clang associations, puns and rhymes.
Retardation of thinking is often seen in depression, the train of thought is slowed down, although still goal directed. The opposite is pressure of speech and this is often seen in mania.
Peseveration is the persistent and inappropriate repetition of the same thoughts. In reply to a question a person may give the correct answer to the first but continue to give the same answer inappropriately to subsequent questions. This is especially seen in ‘organic’ brain disorders like dementia.
Disorders of thought form:
Overinclusion refers to a widening of the boundaries of concepts such that things are grouped together that are not often closely connected.
Loosening of associations denotes a loss of the normal structure of thinking. The patient’s discourse seems muddled and illogical and does not become clearer with further questioning; there is a lack of general clarity, and the interviewer has the experience that the more he/she tries to clarify the patient’s thinking the less it is understood. Loosening of associations occurs mostly in schizophrenia
Three kinds of loosening of association have been described:
Knight’s move thinking or derailment where there are odd tangential associations between ideas.
Talking past the point (= vorbeireden) where the patient seems to get close to the point of discussion, but skirts around it and never actually reaches it
Verbigeration (= word salad = schizophasia = paraphrasia) where speech is reduced to a senseless repetition of sounds and phrases (this is more of a disorder of thought form)
Circumstantiality is where thinking proceeds slowly with many unnecessary details and digressions, before returning to the point. This is seen in epilepsy, learning difficulties and obsessional personalities
Neologisms are words and phrases invented by the patient or a new meaning to a known word
Metonyms are word approximations e.g. paperskate for pen
Derailment (aka entgleisen) is where there is a change in the track of thoughts. There is perserved, but misdirected determining of tendency/goal of thought)
With drivelling there is a disordered intermixture of the constituent parts of one complex thought
Fusion is where various thoughts are fused together, leading to a loss of goal direction.
Omission is where a thought or part of a thought it is senselessly omitted
Substitution is where one thought fills the gap for another appropriate more ‘fitting-in’ thought.
Concrete thinking is seen as a literalness of expression and understanding, with failed abstraction. Can be tested by the use of proverbs.
Thought block refers to the sudden arrest in the flow of thoughts. The previous idea may then be taken up again or replaced by another thought.
As you can tell this is a big subject and I haven’t got onto the historical attempts to characterize schizophrenic thought processes (by Kraepelin, Bleuler, Goldstein, Cameron and Schneider) or the linguistic classification of speech abnormalities in psychosis.
*Quite why they choose this name though it unclear to me, and if anyone else can shed more light on it I would be grateful.