Letter to the editor: Capgras syndrome in the context of multiple myeloma

Wewish to report an interesting case of a 64-yearold woman presenting with an 8-year history of multiple myeloma (urine free light chain protein 0.9 U/l, serum paraprotein concentration 18.2 U/l, serum paraprotein IGA 16.7 U/l and serum beta 25 3.0 mg/l) and recurrent depressive disorder with somatic and psychotic symptoms. Her condition was characterized by depressed mood, loss of energy, feelings of hopelessness and guilt, early morning wakening and motor restlessness alternating with lethargy and paucity of willed actions. Her psychotic symptoms included the delusional belief that she and her family were facing imminent ®nancial ruin, her home was about to be repossessed by baili€s and that her clothing was shabby and dowdy. She also exhibited Capgras syndrome for her general practitioner and psychiatrist, maintaining that they had been replaced by `look-alike' impostors, and for her property, believing that personal items had been stolen and replaced with identical, but inferior doubles. The reported family history was unremarkable, and there was no evidence of substance abuse. A link is suggested between the reported case's delusional beliefs and myelomatous in®ltration of the CNS; however, in the absence of a lumbar puncture, this association cannot be ®rmly established. Capgras delusion is one of the most frequently reported delusional misidenti®cation syndromes (DMS). It is characterized by the belief that a person, usually very close to the patient, has been replaced by a visually similar double. The patient acknowledges that the imposter and familiar person look alike, but maintains the belief that the signi®cant person, in psychological terms, is absent. Neuroanatomical evidence suggests that DMS are commonly associated with right hemisphere dysfunction coupled with bilateral frontal pathology. Interestingly, given the frequent reports of person misidenti®cation in DMS, neuropsychological impairments in facial recognition are often associated with right temporal damage. Tests have shown that neurological patients with right hemisphere lesions are impaired on tasks involving face memory and face perception relative to patients with equivalent damage in the left hemisphere (Warrington, 1984). An MRI scan of the reported case revealed the presence of mild cerebral atrophy, although no focal abnormality was evident. Formal neuropsychological evaluation assessed mental function (Wechsler, 1981), which was placed in the `borderline' range, as well as recognition memory for words and faces (Warrington, 1984), visuospatial perception (Warrington and James, 1991), interference between serial verbal responses (Stroop, 1935) and a comparison of lateralized hemispheric responses rates to tachistoscopic presentation of facial (condition 1) or animate (condition 2) stimuli. Brie ̄y, in each condition, pairs of computer-stored stimuli were viewed for 180 msec in either the left or right visual ®eld. The subject's task was to indicate, within a 3000 msec window, whether the pair was the same (ie identical pictures of the same exemplar) or di€erent, by pressing a preselected key on the computer keyboard (Edelstyn et al., 1996). The reported case displayed a range of processing impairments which are consistent with theories which link DMS to right rather than left hemisphere damage. For instance, her facial recognition memory score fell below the ®fth percentile cuto€ used to indicate impairment in neurological patients. She also failed to demonstrate the normal right hemisphere processing advantage for faces and animate stimuli (Edelstyn et al., 1996). Other studies have also reported the presence of non facial processing abnormalities in DMS patients. This is not surprising, given the accounts of delusional misidenti®cation, which involve inanimate objects (as in the present instance), animals, buildings and places. Abnormalities in right hemisphere performance were also evident during assessment of the reported case's visuospatial abilities. De®ciencies were linked to the perception of the relative position of 2-D objects in space. Other functions, however, for instance shape detection and interpretation of 3-D space in 2-D representation, remained intact. Such an impairment, which is linked to the processes involved in accurately encoding spatial relationships, would certainly have an impact on the