14th November 2023

Psychopathology of Thought Form

In this chapter, we’ll explore thought form – which refers to how a thought is said. We’ll also look at the thought stream, which is how a thought is conveyed. The discrepancy between these will be made more clear when we discuss examples of both later on in the chapter. As with thought content, thought form and thought stream are essential components of the MSE.

Evaluating thought form and thought stream in clinical practice takes experience, as it involves listening closely to what the patient is saying and establishing that the sequence of words (also known as the syntax), the grammar and the ideas are somehow wrong. With experience, this evaluation becomes easier and more automatic.

In clinical practice, both thought form and stream are typically not distinguished, and within the mental state examination (MSE), a commentary about both will often appear under the thought form subheading. However, for learning purposes, it is important to appreciate these differences as pathologies in both will direct the examiner to different differential diagnoses.

Firstly, let’s explore thought form and the different types of psychopathology that can arise.

What is Thought Form?

As previously mentioned, thought form refers to how a thought is expressed in speech. It evaluates how logical, well sequenced, and coherent the sentences spoken by the patient are.

Problems with thought form are most associated with schizophrenia and organic brain disorders. It is important to note that cognitive deficits across most domains are well evidenced to occur in schizophrenia, too. They can have their onset prior to the onset of positive psychotic symptoms, including formal thought disorder. As a result, in clinical practice, it can be difficult to differentiate whether problems in how a thought is expressed are due to a formal thought disorder or due to cognitive deficits. In some patients, both may be contributing simultaneously.

References

• Bowie, C. R., & Harvey, P. D. (2006). Cognitive deficits and functional outcome in schizophrenia. Neuropsychiatric disease and treatment, 2(4), 531–536.

What Causes Formal Thought Disorder in Schizophrenia?

There are a variety of different explanations that are present in the literature, and in truth, the cause may be multifactorial.

• Von Domarus’ law – This refers to when a patient’s inductive thoughts become significantly dominant, and they cease to think deductively. The outcome of this is that two things which are similar become confused to be identical. For example, a psychotic man expresses his female romantic partner as his mother because they are both caring and offer him emotional support.
• Impaired semantic memory – Semantic memory is memory associated with words, concepts and numbers. When this is impaired, the links between words and qualities decrease, which can result in formal thought disorder.
• Impaired direct semantic priming – Thinking of certain words brings other words into one’s mind. For example, if one thinks of the word ‘clock’, it triggers thoughts about ‘seconds’, ‘minutes’ or ‘alarm’. Conversely, an example of indirect semantic priming could be that thinking of ‘clock’ activates ‘alarm’, which activates ‘fear’. Indirect semantic priming is increased, which can lead to thoughts becoming scrambled.
• Theory of mind – This is the ability to understand other people’s perspectives and allows us to empathise. Its loss gives rise to concrete thinking, which we will discuss later, but for now, it is associated with some of the pragmatic errors observed in schizophrenia.
• Dysexecutive problems – These arise in the frontal lobe and, if present, cause problems with planning, abstract thinking, cognitive flexibility, working memory and error monitoring during speech production.

The German neurologist and psychiatrist Karl Kleist (1879 – 1960) was key to the development of descriptive psychopathology. He believed that with schizophrenia, it was more commonplace to observe semantic errors in thoughts rather than grammatical or syntactical. This could result in:

• Verbal paraphasia – Where a word is replaced with an inappropriate word or phrase, but the sentence can still be understood. For example: ‘blood pumping muscular device’ instead of ‘heart.’
• Literal paraphasia – Also known as phonemic paraphasia. This is when the pronunciation (i.e. the sound) of the word changes, but again, the word can still be understood based on the context of the sentence. For example: ‘gelevision’ instead of ‘television.’ At least 50% of the word must be pronounced correctly for it to be considered a literal paraphasia.

References

• Prathap, S. (2019). SPMM Smart Revise. SPMM Course.
• Taylor, M., & Vaidya, N (2008). Disturbances in speech and language. In Descriptive Psychopathology: The Signs and Symptoms of Behavioral Disorders (p. 224-252). Cambridge: Cambridge University Press

Types of Formal Thought Disorder

Poverty of speech

Also known as alogia. The patient will speak with a reduced quantity of speech, there will be less reciprocal conversation, and the patient may not speak spontaneously; rather, they will wait to be asked a question. It is associated with depression and schizophrenia. In fact, a recent study identified a 3-factor model of formal thought disorder as best representative of first-episode psychosis: disorganised thought, poverty of speech and verbosity (Roche et al., 2015).

Pressure of speech

The patient will talk at a faster rate than what would be normal, making it difficult to follow the conversation. It is most associated with being in a manic state. It may be difficult to find a time to interrupt them, and any interruptions may be met with irritability and/or agitation.

Derailment and word salad

Derailment is also known as the loosening of association and knight’s move thinking. Derailment refers to a lack of association between consecutive thoughts spoken by the patient; the speech is incomprehensible; however, the syntax and grammar of the sentence is intact. This can be compared with a word salad, whereby the speech is incomprehensible, but the syntax and grammatical rules are violated, for example, by not having prepositions, conjunctions or articles present. An example of a word salad could be: ‘Look photo clock mum to folder job centre.’

Derailment and word salad most commonly occur in schizophrenia.

Neologism

A neologism is a completely made-up word. It can also refer to using a legitimate word but to mean something different, e.g. ‘smadar’ for clock (new) or ‘light’ for water (different).

Stock words

A stock word is similar to a neologism in that it is either a completely made-up word or a pre-existing word that is used to mean something different. However, it is used in an idiosyncratic way repetitively, in a variety of situations and will often be overused. For example, ‘I ride my glanar (bike?) to work every morning. Except when it’s glanar (raining?), then I take the bus because I don’t want to get wet. Once I’m at work, I say glanar (hello?) to my colleagues, and I sit down at my glanar (desk?) to get on with some work.

Stilted speech

Stilted speech is pompous, overly formal speech that is inappropriate in the context spoken. It involves vocabulary and grammar that would be more appropriate in formal writing rather than conversational speech. It also consists of unnecessary repetition or corrections.

It is associated with autistic spectrum disorder, schizophrenia, or schizotypal personality disorder. With schizophrenia, it is thought to represent a difficulty in understanding the relationship between language and context (known as pragmatics) (Covington et al., 2005).

Concrete thinking

Concrete thinking is when a patient interprets things literally. Their understanding of abstract concepts is limited. They may misunderstand things like metaphors, which makes the term ‘concrete’ thinking rather ironic.

Developmentally speaking, very young babies think concretely and cannot conceive of objects unless they are physically present. It is essential for the development of the theory of mind, an important social skill. Eventually, they develop the ability to think more abstractly and theoretically.

Concrete thinking is pathologically present in autistic spectrum disorder, formal thought-disorder-type schizophrenia, fronto-temporal dementia and intellectual disability.

Illogicality

This refers to when the patient’s logic is flawed. For example, a patient being asked when they do their gardening at home, and the patient replying that he does it at night because he can see better. It is most associated with schizophrenia.

References

• Fish, F., Casey, P., Kelly, B. Fish’s Clinical Psychopathology. Signs and Symptoms in Psychiatry. Cambridge University Press. 4th Ed 2019.
• Roche, E., Lyne, J. P., O’Donoghue, B. et al. (2015). The factor structure and clinical utility of formal thought disorder in first episode psychosis. Schizophrenia Research. 168, 92-98.
• Oyebode, F. (2015). Sims’ Symptoms in the Mind. Textbook of Descriptive Psychopathology. Elsevier: 5th Ed.
• Prathap, S. (2019). SPMM Smart Revise. SPMM Course.
• Covington, M. A., He, C., Brown, C., Naçi, L., McClain, J. T., Fjordbak, B. S., Semple, J., & Brown, J. (2005). Schizophrenia and the structure of language: the linguist’s view. Schizophrenia research, 77(1), 85–98.

How is Formal Thought Disorder Measured?

There are two commonly used scales:

• Thought language & communication scale (Andreasen, 1979), which provides concise definitions of a range of features of thought disorder. The patient is assessed clinically, and the clinician rates the degree of disorder present in the patient’s speech. The reliability was found to be ‘quite good for most of the terms defined.’ One problem with this scale is that not all formal thought disorder types are included.
• Thought disorder index (Johnston & Holzman, 1979), which is similar but has been shown to be more sensitive. The assessment involves two standardised procedures: answering questions about the Rorschach ink-blots and performing a Wechsler adult intelligence scale. Unfortunately, this is simply too time consuming for clinical practice, and the scoring requires an expert to perform; therefore, it remains a research tool.

References

• Andreasen, N. C. (1979). Thought, language, and communication disorders: I. Clinical assessment, definition of terms, and evaluation of their reliability. Archives of General Psychiatry, 36, 1315-‐-1321
• Johnston, M. H., Holzman, P. S. (1979). Assessing Schizophrenia Thinking. San Francisco, CA: Jossey-Bass.
• Prathap, S. (2019). SPMM Smart Revise. SPMM Course.

Thought Stream

As previously mentioned, although in clinical practice, it is commonplace to amalgamate thought form and thought stream, it is important for learning purposes to understand the difference and be able to evaluate both when performing an MSE.

Let’s look at the thought stream and the different types of psychopathology that can arise.

Thought stream refers to how a thought is delivered. For example, is it delivered very quickly or very slowly? Let’s have a look at what we should evaluate when considering the thought stream.

Flight of ideas

Different thoughts are spoken about in accelerated succession without a general direction, making the conversation difficult to follow. There is a logical link between each idea, which can be established by the examiner, but it is tenuous. The links arise from three sources:

• The thoughts the patient has.
• The words the examiner or anyone else in the room says
• Other general perceptions from the environment, e.g. the patient seeing an object in front of him or feeling cold.

Verbal associations can arise from multiple sources, and below are five of the most common examples:

• Alliteration – The occurrence of the same letter at the beginning of successive words
• Assonance – The occurrence of the same syllable between successive words.
• Clang associations – The presence of similar sounds between successive words.
• Rhyming – Interestingly, in schizophrenia, the rhyming link usually occurs with first syllables rather than those seen in poetry or mania, which are more classically end syllables. For example: ‘Last week I went to the park; oh look, it’s dark now, I prefer the light to the dark; speaking of preferences, I prefer pizza to pasta; I was in Italy last year, have you been?’
• Puns – A play on words that uses the different possible meanings of those words. For example, ‘a motorbike can’t stand on its own because it is two-tired.’

Flight of ideas is most associated with being in a manic state. This may be caused by functional conditions like bipolar affective affective disorder or schizoaffective disorder. The aetiology of a manic state may also be organic, including stroke, neoplasm or traumatic brain injury. It may also be caused by drug misuse, for example, with stimulants. In organic conditions, the areas of the brain most likely to be affected are the basal ganglia, frontal and temporal cortices, and the thalamus and hypothalamus (Barahona-Corrêa et al., 2020).

In comparison to hypomania, patients with mania will present with a more severe flight of ideas, whereby the link between sentences will be more tenuous and will often present with the goal of their conversation being lost, making it impossible to understand the intent of their speech. Conversely, hypomanic patients will more frequently re-join the path of their conversation and achieve its goal. In addition to mania and hypomania, flight of ideas may occur in schizophrenia during periods of excitement, although this is rare.

Thought slowing

The train of thought can slow down, and this is most apparent with moderate to severe depression but also in manic stupor. There is a long response latency period: in other words, when asked a question by the examiner, the patient will not reply for what may be a long time before eventually speaking slowly and monotonously. Furthermore, registering information can become more difficult, and distractibility can worsen, both of which can make it harder to make decisions. The patient may describe their mind as seeming more ‘fuzzy’ or ‘clouded.’

Importantly, however, the thinking remains goal-directed.

Note that the concept of thought slowing is an objective measure. The subjective experience of the thinking process being slower is called inhibited thinking.

Crowding of thought

This is when there are too many thoughts occurring at the same time, so much so that the patient perceives this as if their brain were about to explode from the tremendous pressure caused by this. The thoughts are a mixture of logical and illogical. It is unpleasant and experientially different from the flight of ideas which is seen in mania. It is also objectively different from the flight of ideas, as here, the thought processes do not necessarily appear to be accelerated to the examiner. Crowding of thought is seen in schizophrenia (there is a passivity to the compression of thoughts that are experienced as being under external control) and depression.

Circumstantiality

A patient presenting with circumstantial thoughts will respond to a question by talking around a subject and digressing from the point, exhausting many banal and irrelevant associations (details) before finally returning to answer the question that was asked originally. The patient may fill their speech with apologies depending on their awareness of how long winded their conversation has become, but nevertheless may continue in this pattern. It may be easier to imagine this pictorially by looking at the diagram below, showing the stream of thought:

Circumstantiality is seen in obsessional personalities, whereby the patient’s desire for detail manifests in their thoughts, so much so that it heavily impedes the goal of their thoughts being achieved. The aetiology also includes organic disorders: temporal lobe epilepsy, alcohol-associated dementia and intellectual disability.

Tangentiality

When asked a question, the patient’s thoughts will journey on a tangent, going off topic and not returning to respond to the question asked (unlike circumstantiality, where the question is eventually answered). A patient presenting with circumstantiality or tangentiality may prompt the examiner to increase their use of closed questioning to ensure a timely review.

Perseveration

Perseveration is the conscious continuation of a thought or act beyond which it is deemed to be appropriate. For example, a patient is asked what the day of the week is and correctly replies that it is ‘Monday.’ When asked what day it was yesterday, they reply ‘Sunday.’ When asked what day it is tomorrow, they reply, ‘Sunday. Sorry, no, I meant to say Sunday.

Although it can be present in schizophrenia, it is mainly found in the following organic conditions: delirium, epilepsy and dementia. It can also be secondary to substance misuse.

Echolalia

Echolalia refers to the patient repeating part of the examiner’s speech without being asked to do so. 

It is most associated with autistic spectrum disorder but can be seen in Tourette syndrome, schizophrenia, dementia and traumatic brain injury.

Thought blocking

Thought blocking occurs when the patient is talking, and there is a sudden cessation in their train of thought for no obvious reason. It is not caused by distraction by external stimuli or other thoughts, and when questioned about it, the patient is unable to provide an explanation for it. The patient may try to restart the conversation, which may start on a completely different topic. It may look like the patient is having an absence seizure. However, neither motor symptoms (that are classical in absence seizures, e.g. lip smacking, eyelid flutters or chewing motions) nor amnesia are present.

It’s most associated with schizophrenia, although it may appear if the patient is very tired or anxious and so preoccupied that they can lose their train of thought.

References

• Oyebode, F. (2015). Sims’ Symptoms in the Mind. Textbook of Descriptive Psychopathology. Elsevier: 5th Ed.
• Fish, F., Casey, P., Kelly, B. Fish’s Clinical Psychopathology. Signs and Symptoms in Psychiatry. Cambridge University Press. 4th Ed 2019.
• Prathap, S. (2019). SPMM Smart Revise. SPMM Course.
• Barahona-Corrêa, J. B., et al. (2020). Right-sided brain lesions predominate among patients with lesional mania: evidence from a systematic review and pooled lesion analysis. Translational psychiatry, 10(1), 139.