I once knew someone who described an incidence of psychosis that happened when she had to be suddenly taken off of a steroid medication. The doctors knew that psychosis was a possibility when going cold turkey, so she was hospitalized for observation for a couple of days. Afterwards, she said that if she had seen a helicopter land in her room, she wouldn’t have thought “how can a helicopter land there - there are four floors of hospital above me?”, she’d have thought “so that’s how the mafia are delivering the illegal drugs.”
It’s not just hallucinations or odd thoughts suddenly hitting the mind, it’s also disordered thinking.
Another term used is Erotomania or erotic paranoia, where the deluded person believes that another person is secretly in love with the deluded individual, but just needs help to break through the family and over-protective security types like LSLGuy :p, who are blocking contact.
In Canada, one of the best examples was Robert Keiling, a Saskatchewan farmer who was convinced Anne Murray was in love with him. He tried to make contact with her for over 30 years until his death, despite stays in mental hospitals and five years of Her Majesty’s hospitality.
After Hinckley had been in prison for a few years, he supposedly had a correspondence relationship with a woman who was a convicted murderer. Jay Leno predicted it wouldn’t work out: “It creates a tension when a woman’s more successful in her career than her husband is”.