The role of the right prefrontal lobe in Capgras syndrome

Capgras syndrome describes the delusional belief that a person, usually closelyrelated, has been replaced by an imposter. Initial explanations for this condition werepsychodynamic in nature, until increasing reports of co-morbid cerebral damageencouraged neurological explanations to be explored.A two route model of facial processing prompted the suggestion that Capgrassyndrome is a mirror image of the neurological condition prosopagnosia.It has been hypothesised that Capgras syndrome results from damage to the covertfacial recognition pathway, evidenced by the decreased autonomic arousal reported insome patients when encountering loved ones. This pathway has been mapped ontoneuroanatomical models of visual processing, with damage to the dorsal pathway thoughtto underlie the delusion.In addition to these models of disconnection, it has also been theorised that thedelusion results from right cerebral hemispheric damage. More recently, frontal lobeabnormalities have been suggested to be involved in the pathogenesis of the disorder.It has been suggested that secondary damage to the frontal lobes, particularly theright, is likely to be necessary for formation of such a far-fetched delusion. Ultimately, itis likely that deficits in visual processing need to interact with altered cognitive reasoningand affective responses in order to produce the delusion.