[Delusional Misidentification Syndromes in Organic Brain Disorders]

Area of Science:

• Neuroscience
• Psychiatry
• Neurology

Background:

• Delusional misidentification syndromes (DMSs) are characterized by fixed, false beliefs regarding the identity of people, places, or objects.
• These syndromes, including Capgras and Frégoli syndromes, are linked to focal neurological lesions and neurodegenerative diseases like dementia with Lewy bodies.

Purpose of the Study:

• To investigate the neural underpinnings of lesion-induced DMSs using lesion network mapping.
• To propose a novel model explaining the delusional belief content in DMSs beyond existing frameworks.

Main Methods:

• Lesion network mapping was employed to identify brain regions functionally connected to lesion sites in patients with DMSs.
• A review of existing models, including the prosopagnosia-based model for Capgras syndrome, was conducted.

Main Results:

• The left retrosplenial cortex and right ventral frontal cortex/anterior insula showed functional connectivity with most lesion locations associated with DMSs.
• Existing models, such as the dual-route model for Capgras syndrome, do not fully account for the spectrum of DMSs.

Conclusions:

• DMSs may result from disruptions in the functional connectivity between specific brain regions, notably the retrosplenial cortex and frontal-insular areas.
• A proposed new model posits that the core mechanism of DMSs involves a dysfunctional link between external perception and internal autobiographical memory retrieval.