Our understanding of the behavioral and psychological symptoms associated with dementia has been increased in recent years by studies in clinical neuroscience, behavioral research, and clinical pharmacology. Findings of those studies have contributed to advances in assessment and diagnosis, and are stimulating further research. The critical importance of government regulations affecting delivery of care and development of treatments is much better known now than in the past.

There is increasing consensus that psychosis associated with dementia (delusions and hallucinations, etc.) represents a specific syndrome that can be clinically distinguished from less specific behavioral symptoms such as aggression and agitation. Dr. Schneider reviewed epidemiologic studies and concluded that the prevalence of psychosis in persons with Alzheimer's disease is substantial (approximately 20 percent).

Clinical characteristics of dementia-related psychosis include simple delusions, such as a belief that people are stealing things or are dangerous to the patient. Bizarre, complex, or "first rank" delusions are uncommon. Delusions are more frequent in dementia associated with Alzheimer's disease (23%) than in vascular dementia (8%), although the prevalence of hallucinations is similar (13% each).

Misidentification of persons/places and visual hallucinations are frequent. Patients with dementia-related psychosis commonly present with agitation, aggression, or depression. Their psychotic symptoms frequently wax and wane, but cause major disruption for at least one month.

Patients with Alzheimer's disease who have psychotic features may show more rapid decline in overall clinical course than do patients with Alzheimer's disease who do not have psychotic features. Moreover, neuropsychological and neuro-imaging studies have demonstrated evidence for frontal/executive pathology in psychosis of Alzheimer's disease. Diagnosis of psychosis of dementia (and Alzheimer's disease in particular) may lead to more appropriate treatment decisions. Chief among these is treatment with low dosages of atypical antipsychotics.