A Study of the Effectiveness and Safety of Risperidone Versus Placebo in the Treatment of Patients With Hallucinations and Delusions Associated With Alzheimer's Disease

Inclusion Criteria: * Diagnosis of Alzheimer's disease according to criteria of Diagnostic and Statistical Manual of Mental Disorders, 4th edition (DSM-IV) * Mini-Mental State Examination (MMSE) score of not greater than 23 * Behavioral Pathology in Alzheimer's Disease (BEHAVE-AD) psychotic score of \>=2 for any item in the psychotic cluster * occurrence of hallucination or delusion after onset of symptoms of dementia at least 28 days before screening. Exclusion Criteria: * Patients with a disease that could significantly diminish cognitive function (e.g., Parkinsonism, Huntington's disease, Creutzfeldt-Jacob disease, dementia of Levy body type, vitamin B12 or folic acid deficiency) * persistent dementia or amnestic disorders according to DSM-IV criteria * occurrence of hallucination or delusion only while delirium is observed * psychiatric symptoms induced by psychosis (e.g., schizophrenia, schizoaffective disorders, delusional disorders, depression or bipolar disorders) * history of neuroleptic malignant syndrome (a rare psychotropic-drug reaction, which may be characterized by confusion, reduced consciousness, high fever or pronounced muscle stiffness)