Since 1993, Vandetanib msds five drugs have been marketed in the US for the treatment of AD (donepezil, galantamine, rivastigmine, tacrine, and memantine). Antidementia drugs have been proven to mitigate the symptoms of AD but their influence on long-term course and life span is not established. Recent observational studies suggest that cognitive and functional benefits continue over many years for patients who persist in their treatment, beyond the relatively short duration of benefit evident in clinical research trials [9-11]. Antidementia drugs are not thought to influence longevity, but there are conflicting reports in the literature. Several observational studies [11-14] found no relationship between the use of any antidementia drug regimen (cholinesterase inhibitor or memantine or both) and survival when users were compared with untreated patients.

Two large cross-sectional studies that involved retrospective data analysis reported that the use of cholinesterase inhibitors versus no treatment significantly increased survival in nursing home patients. Both tacrine use [15] (hazard ratio = 0.76, confidence interval (CI) = 0.70 to 0.83) and donepezil use [16] (hazard ratio = 0.89, 95% CI = 0.83 to 0.95) were associated with significantly reduced mortality. This study evaluated a broad range of covariates suspected to influence survival and assessed the use of antidementia drugs in a time-dependent analysis. Materials and methods Participants Informed consent was received from all patients involved in the study. The patients were evaluated at the Baylor College of Medicine Alzheimer’s Disease and Memory Disorders Center.

The study began in 1989 and enrolled 1,833 patients with dementia as of 31 December 2005 (censoring date). All members of this community-based Entinostat cohort agreed to participate in a database approved by the institutional review board of the Baylor College of Medicine. Six hundred forty-one participants met the established criteria for probable AD as determined by the National Institute of Neurological and Communicative Disorders and Stroke and the Alzheimer’s Disease and Related Disorders Association (now known as the Alzheimer’s Association) [17] and were included in this analysis. Vital status is obtained from the National Death Index every 6 months and allows calculation of survival time for all enrolled subjects.

Exposure Cumulative drug exposure to antidementia drugs (cholinesterase inhibitors or memantine or both) or antipsychotic drugs (typical or atypical) was determined from the onset of symptoms. The onset of first symptoms is estimated by a physician using a standardized algorithm to the nearest half-year method [18]. Start and stop dates of drug exposure are recorded at the first clinic visit by history obtained from the patient and caregiver along with a review of medical and pharmacy records. This information is updated at each return visit to the center.