Explain why formal thought disorder is best assessed through spontaneous, unstructured speech rather than structured questioning.

Structured, closed questioning gives the patient a narrow, pre-organised framework to answer within, which can mask a genuine underlying disturbance in how they organise their own ideas when left to do so freely. Formal thought disorder is fundamentally a disturbance in the structure of thinking itself, and this shows up most reliably when a patient has to generate and connect ideas on their own, as in open, spontaneous conversation or when asked to describe something at length in their own words. Relying only on structured questions risks a false reassurance that thinking is organised, when the difficulty only becomes apparent once the patient is given room to think and speak freely.