Dementia in schizophrenia

Cognitive impairment is a well-recognised and cardinal feature of schizophrenia (Keefe 2007). Given the biological effects of ageing on the brain, it is important to consider the cognitive manifestations of schizophrenia in the context of ageing. Significant issues include the natural history of cognitive dysfunction over the lifespan, its progression to dementia, and the temporal relationship between psychosis and cognitive deficits. In this context, it helps to have a precise definition of cognitive impairment, and we find the following useful: ‘a level of cognitive functioning suggesting a consistent severe impairment and/ or a significant decline from premorbid levels considering patients’ educational, familial and socioeconomic background’ (Keefe 2007). Cognitive impairment has a trajectory over the course of schizophrenia that is different from that of psychotic symptoms and it may contribute to a poor functional outcome in older patients (Davidson 1995).