A man with no preceding change in mood, perception, or personality suddenly and inexplicably becomes convinced, out of nowhere, that a television broadcaster is sending him personal messages, with no other experience that could account for how this belief arose. Before revealing the answer: is this a secondary delusion?
No. This is better understood as a primary delusion, not a secondary one — the defining feature of a secondary delusion is that it can be traced back to, and understood in light of, another underlying morbid experience (mood, hallucination, or personality style), and no such preceding experience is described here; the belief arises suddenly and without any such traceable origin.
References
- Casey, P. & Kelly, B. (2019). Fish's Clinical Psychopathology, 4th ed. Ch. 4, 'Disorders of Thought and Speech'.