Right-hemisphere encephalopathy in elderly subjects with schizophrenia: evidence from neuropsychological and brain imaging studies

Rationale. Cognitive impairment is a recognised feature of schizophrenia. Elderly patients with early-acquired schizophrenia are seriously affected, with a proportion of them showing clinically significant dementia, not accounted for by any recognized degenerative processes common in this age group, such as Alzheimer's disease. Progression of cognitive deficits is described in elderly institutionalised patients, but disputed amongst community dwelling subjects. The pattern of cognitive deficits in this age group is not yet clearly defined, although there is some evidence that it differs from that in Alzheimer's disease. There is little evidence of any underlying specific brain abnormality. Objectives. To characterize the neuropsychological deficits in elderly schizophrenia patients and distinguish them from those in Alzheimer's disease. To establish the presence of underlying structural brain abnormality using MRI. Methods. Twenty-eight elderly schizophrenia patients with onset before the age of 45 years carried out neuropsychology tests. Twelve scored in the dementia range and were compared with 16 equally impaired patients with early Alzheimer's disease. Thirteen of the schizophrenia patients consented to brain MRI. The imaging data were analysed using a newly developed automated method of measuring CSF volume distributions and compared with data from 30 age-matched normal controls. Results. The schizophrenia group was more impaired on visuo-spatial tasks than the Alzheimer's group but less impaired on corresponding verbal tasks, despite similar overall cognitive impairment. The MR scans revealed right-sided enlargement of ventral CSF spaces in the schizophrenia patients especially in the posterior third, and this correlated with their impaired performance on visuo-spatial tasks. Conclusions. The results suggest that right hemisphere impairment underlies the specific profile of cognitive impairment in elderly patients with schizophrenia.