Confounding and the dementia of schizophrenia

Schizophrenia is often said to cause dementia, and previous studies have found cognitive impairment to be associated with schizophrenia. It is possible, however, that other causes of dementia and the study of patients not representative of all schizophrenics have contributed to these findings. The neuropsychological test scores of 26 schizophrenic outpatients were compared to those of 82 other patients with a history of psychosis. After other known causes of cognitive impairment were controlled for, the schizophrenics were not found to have cognitive impairment when compared to the other patients.