Fascinating article about how the delusions of psychosis incorporate culture and reflect cultural changes https://www.vice.com/en_uk/article/k7qqb3/psychotic-delusions-change-with-the-times-theyve-started-to-include-covid-19

However, it contains an unrecognised reality loop which is common in discussions on this.

It mentions the Truman Show delusion as an example of how a cultural artifact, the film 'The Truman show', started showing up in people's psychosis.

Uncredited, but The Truman Show film is clearly based on the Philip K Dick book Time Out of Joint https://en.wikipedia.org/wiki/Time_Out_of_Joint where the protagonist lives in a simulated 1950s world populated by actors to keep him solving problems presented to him as newspaper puzzles.

Philip K Dick read very widely but also experienced psychosis himself, largely due to fueling himself with amphetamines. Time Out of Joint is very likely based on his extensive reading of psychiatry and his own experiences of altered reality.

So The Truman Show delusion is not really an example of popular culture influencing delusions, it's an example of delusions influencing popular culture. The only difference is now people have a label for it.