Pseudodementia in schizophrenia and mania

The importance of differentiating depressive pseudodementia from true dementia seems to be well recognized by psychiatrists, yet there seems less recognition that other functional psychoses in the elderly can present with symptoms of cognitive impairment. In this report, we describe two patients--one suffering from late onset schizophrenia and one from a manic illness--who were diagnosed as suffering from dementia in the early stages of their illnesses. We discuss some of the difficulties in making diagnoses in these cases which include an historical tendency for clinicians, including psychiatrists, to assume an organic aetiology for first presentation psychoses in old age. Although the concept of pseudodementia has been criticised in recent years, we conclude that it retains its clinical utility in that it orientates the clinician to the importance of recognizing treatable functional psychoses in the elderly.