15th November 2023

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.