Specific Interventions for Agitation in Alzheimer's Disease

Inclusion Criteria 1. Diagnosis of probable AD according to DSM-IV, which show high agreement with NINCDS-ADRDA criteria (McKhann et al., 1984); kappa = 0.81 (Chui et al., in press). 2. At least a two-week history of two or more agitated behaviors from the Agitation Screening Inventory (a shortened version of the 24-item Revised Memory and Behavior Problem Checklist) (RMBPC; Teri at al., 1992), occurring at least once weekly, and rated by the caregiver or nursing staff as at least moderately distressing. 3. Not planning a change in living situation or placement during the investigational period. 4. Stability (of dose and type) of medications for nonexcluded concurrent medical conditions (i.e. thyroid disease, anemia, cardiac disease) for four weeks prior to baseline. 5. Ability to ingest oral medications and participate in all scheduled evaluations. 6. A sixth grade education or a work history sufficient to exclude mental retardation. 7. 50 years of age or older. 8. Medically acceptable for experimental drugs as confirmed by physical evaluation and laboratory tests. 9. Modified Hachinski Scale score of 4 or less. Exclusion Criteria 1. Neurological diagnoses other than AD which affect cognitive function. These include Parkinson?s Disease, tumors, hydrocephalus, history of significant trauma, and seizure disorder). 2. A diagnosis of delirium by the Confusion Assessment Method (CAM, Inouye et al., 1990). 3. A diagnosis of dementia related to infection with human immunodeficiency virus (HIV) or amnestic disorder, as defined by DSM-IV. 4. Known hypersensitivity to risperidone or gabapentin. 5. Alcohol or drug abuse within the past year. 6. Serious, unstable medical illnesses (e.g., unstable angina, poorly controlled diabetes mellitus, labile hypertension) 7. Any medical problem that would cause or exacerbate agitated behaviors (including unstable thyroid dysfunction, electrolyte disturbances, urinary tract infection, fecal impaction, respiratory disease complicated by hypoxia or hypercapnia, etc.) 8. Any psychotropic medications or other medications which may cause or exacerbate agitated behavior. Patients taking these medications may participate in the study if the drugs can be successfully discontinued during the washout period and the remainder of the study, and if after discontinuation they still meet inclusion criteria for the investigation. Excluded medications include: antipsychotics; antidepressants; anxiolytics; CNS stimulants; anti convulsants; and sedative hypnotics. 9. Significantly abnormal laboratory findings. 10. Significantly abnormal EKG findings. 11. Conditions such as blindness, deafness, or other disability that may prevent the patient from participating in the study. 12. Current participation in any other investigational drug study or treatment.