Anticholinergic Drugs and Memory in Patients with Parkinson's Disease: Surprise

Geriatricians occasionally encounter patients in various stages of a dementing illness who have a delusion that a close family member has been replaced with an imposter. One of the most interesting cases of this kind that I saiv a few years ago involved a gentleman 80 years of age who was brought to me by his wife because he was constantly trying to have sex with her. This change in behavior had been evident for over a month by the time I saiv them. He had been correctly diagnosed as suffering from the relatively early stages of Alzheimer’s disease. As the patient spoke about his increasing sexual interest in his wife, it became clear that he thought his wife had been replaced by another woman “who looked much like my wife, but is much more attractive! ” The more he spoke, the angrier his wife became, because he was having an affair with another woman, even though she was his wife-a confusing situation for all of us. A systematic review of the literature on this disorder was recently published. Forstl et al,’ from the Institute of Psychiatry in London, reported a case of a 77-year-old woman with early dementia of the Alzheimer type who developed the paranoid delusion that her husband had been replaced by an imposter. They found that the computed tomography (CT) scan showed mild generalized cortical atrophy but marked atrophy of the parietooccipital cortex. They then searched the medical literature and reviewed the cases of 45 patients over age 60 years who showed a Capgras delusion. Focusing on their 77-year-old patient, the authors noted that she had strongly accentuated atrophy of the calcarine and parietooccipital sulci and a mild generalized cortical atrophy. The combination of a Capgras delusion associated with a specific cerebral lesion detected on CT scanning is of interest. However, when the authors performed neuropsychological tests, their patient demonstrated a global, rather than a specific, cognitive deterioration and no particular visual or facial perception impairments. Their patient had a clinical history of a depressive episode with a concomitant confusional state aggravated by her first electroconvulsive treatment (ECT), a persistent mild cognitive impairment with gradual deterioration, and the absence of signs or symptoms of an underlying medical disorder suggesting a diagnosis of dementia of the Alzheimer’s type. Of interest, her first depressive episode was dominated by nihilistic delusions that has been called Cotard syndrome. Forstl et all note that the coexistence of Cotard syndrome and Capgras delusion was reported earlier in a young patient with paranoid schizophrenia and feel that the fact their patient exhibited both syndromes over the course of her illnesses, underlines the nonspecificity of such bizarre symptoms. A transient Capgras delusion in an elderly woman has even been observed after ECT2. In their review of the cases of 45 patients over age 60 years who showed a Capgras delusion, Forstl et all found that 25 suffered from dementia or other chronic organic mental disorders, 20 were afflicted with paranoid disorders, 14 were at least moderately depressed, and 12 were disorientated. Seventeen of the 45 patients had CT scans, 12 of which showed global cerebral atrophy. Right hemisphere infarcts were described in two elderly patients with Capgras delusions. Overall, these findings may indicate that global brain atrophy or dysfunction may decrease the threshold for bizarre psychotic phenomena which could be triggered by minor focal lesions preferably of the right hemisphere. The authors concluded their analysis of the published cases by suggesting that the Capgras phenomenon, which may occur as a predominant feature of various neuropsychiatric disorders of the elderly, is not specific to any underlying disease process or localized brain abnormality. The development of this delusion occurs most frequently in organic mental disease, often a dementia, brain infarction, or a combination of global and focal lesions. However, an association with some specific underlying brain disease is not established.