Transitory Thinking
Transitory thinking is a form of formal thought disorder in which the ordinary constancy of a completed thought breaks down: thoughts slide off course, get replaced by unrelated ones, or are dropped altogether mid-course, and the grammar and sentence structure of speech are disturbed as a result.
This has traditionally been described as arising from a breakdown in the normal 'constancy' of thought — the property by which a completed thought would ordinarily stay fixed in content until deliberately replaced by a new, consciously derived one — with derailment, substitution, and omission representing three specific ways that constancy can fail.
Also known as
- Derailment
- Thought slides sideways onto a subsidiary or tangential thought rather than continuing along its original line.
- Substitution
- A major thought is replaced entirely by a subsidiary one, which takes its place.
- Omission
- A thought, or part of a thought, is dropped entirely, leaving a senseless gap.
Recognition features
- Thoughts and sentences shift, are replaced, or are cut short in ways that disrupt ordinary grammar and sentence structure
- The disruption affects the constancy of individual thoughts, rather than the broader continuity or organisation of the whole train of thinking
- May present as a sentence that begins on one topic and, without explanation, ends on an unrelated one
- Distinguished from a simple gap in attention by the senseless, structurally disruptive quality of the interruption
Eliciting it at interview
- Listen closely to sentence-level structure during spontaneous speech, noting whether individual sentences derail mid-course, get replaced, or are left syntactically incomplete
- Ask the person to elaborate on a sentence that seemed to change direction partway through, and note whether they can account for the shift
- Compare with desultory thinking by checking whether the interruption creates an actual structural gap (as here) or simply an intrusive but grammatically complete extra idea
Distinguishing features
- Differs from desultory thinking in that here the grammatical and syntactical structure of speech is itself disturbed, whereas desultory thinking remains grammatically correct throughout
- Differs from drivelling thinking in that the overall preliminary plan for a complex thought is not necessarily present here in the way it is in drivelling
- Omission is distinguished specifically from desultoriness by involving an actual interrupted gap in the intended thought, rather than a loosening of the connections between otherwise intact ideas
Common misconceptions
- That transitory thinking is simply 'getting distracted'; the disturbance affects the grammatical structure of thought itself, not merely the topic under discussion
- That derailment, substitution, and omission are easily told apart at the bedside; in practice they can be difficult to distinguish from each other and are often considered together as a single cluster
Related phenomena
Formal Thought Disorder · Drivelling Thinking · Desultory Thinking
Practice this
A patient's sentence begins clearly on the topic of his medication, but partway through, without any explanation or connecting logic, the sentence structure breaks down and finishes on an entirely unrelated topic, with grammar disrupted in the process. What is this? · A patient begins a sentence with a complete, grammatically intact plan to describe a complex worry involving several connected concerns, but as she speaks, the parts become muddled and jumbled together so the overall meaning is lost, even though she remains aware something is not right. Before revealing the answer: is this transitory thinking? · A patient's train of thought is repeatedly disrupted mid-course. Before revealing the answer, decide what distinguishes desultory thinking from transitory thinking. · A patient's individual thoughts and sentences seem to lose their constancy mid-course. Before revealing the answer, decide what distinguishes transitory thinking from drivelling thinking. · You suspect transitory thinking in a patient. Before revealing the answer, decide how you would assess for this. · Explain why transitory thinking is described as affecting the constancy of individual thoughts, rather than the broader continuity or organisation of the whole train of thinking.
Illustration
Mid-sentence, a 25-year-old man describing his weekend says, "I went to the shop to buy some the curtains were definitely," then stops, unable to explain what he had intended to say or how the sentence had changed course, and continues on an entirely unrelated topic without acknowledging the break.
References
- Casey, P. & Kelly, B. (2019). Fish's Clinical Psychopathology, 4th ed. Ch. 4, 'Disorders of Thought and Speech'.