Delusional companion syndrome

Delusional companion syndrome is considered a neuropathology of the self, specifically a delusional misidentification syndrome. Affected individuals believe certain non-living objects possess consciousness and can think independently and feel emotion. The psychosis must coexist with a detectable brain pathology for delusional companion syndrome to be diagnosed. The syndrome is most often identified in patients who suffer from damage to the brain due to physical trauma, neuronal degeneration or developmental abnormalities. Especially in the latter case, patients also tend to present with many other symptoms and are diagnosed as having other established conditions. Comforting objects like cuddly toys are often the focus of delusion.
Causes.
Delusional companion syndrome can be caused by acute injury or chronic disease. The following are known to have been direct causes:
Neuropathology.
Little detail is known about the specific causes of delusional companion syndrome. It is thought that damage to the neocortex may be the direct cause of this psychosis. Shanks and Venneri (2002) found unique and abnormal blood flow centred in the right parietal lobe of three patients with Alzheimer's disease. Severe processing deficits were found in brain areas responsible for visuospatial and visuoperceptive information, whereas memory and language abilities were preserved relatively well.
Popular culture.
In the 2007 film "Lars and the Real Girl", the main character believes a sex doll that he bought is actually a girl that he met over the Internet and expects his friends and family to treat her like a real person too. In the likewise 2007 released videogame "Portal", the player is given a box with a heart symbol, called 'companion cube' to solve puzzles. Following this, the game frequently reminds the player that the cube is not in possession of sentience.