Current research on monothematic delusions

Capgras delusion is the belief that someone emotionally close to you - typically a spouse - has been replaced by an identical-looking impostor. Cotard delusion is the belief that you are dead. Fregoli delusion is the belief that you are continually being followed by a group of people whom you cannot recognize because they are disguised. Mirrored-Self Misidentification is the belief that your own reflected image is a person who is following you around.

This got me thinking about other similar monothematic delusions, possibly as yet uncategorized. I started to think about the belief that every time you drop the toast it lands butter side down, or that you would have gotten a promotion but your boss hates you, cultural delusions relating to bottom size, or attractiveness of famous people, the delusion that Paris Hilton is special and interesting. That Eurovision is a showcase of great pop music. I thought about the delusion that cricket is interesting to watch, or that using birth control is evil and will cause an omnipotent being to become angry and want to roast you on High for the eternity version of an hour. The delusion that burning the very substrate that we stand on and living in the fumes of the smoke wouldn’t have any effect on us or our surroundings, the delusion that owning a shiny car makes you a more interesting and attractive person. The delusion that we will never die or get old. The delusion that if you keep buying the lotto ticket one day you will win and be swept away on a tropical holiday that will last the rest of your life. The delusion that cow fetus rubbed into your eye skin will make you pretty like a movie star and never feel lonely. The delusion that superannuation and income insurance and a savings plan means that nothing bad will ever happen to your family, and you wont have to feel grief.

Sufferers from these kinds of monothematic delusions are not delusional about anything else, and readily acknowledge the extreme implausibility of the belief they hold; but they nevertheless do not relinquish the belief. Bizarre though these conditions seem, they are not uncommon: for example, the most recent review of research on the Capgras delusion reviewed 570 cases.

From here http://www.maccs.mq.edu.au/research/programme/belief.htm