Delirium is differentiated from chronic confusion or Alzheimer's dementia (AD) and acute psychosis by an abrupt onset, a reduced ability to maintain attention, and a potential clinical reversibility. Despite the significance of delirium in the elderly, little is known about the prevalence of this illness in long-term care (LTC), especially in rural LTC facilities. Although delirium is a reversible cognitive disturbance in the elderly, the scope of the problem in LTC is largely neglected in the literature and referred to by other labels (e.g., pseudo-senility and acute brain syndrome). A primary care provider is generally not immediately available in the rural LTC facility to diagnose this illness. As a result, elders with delirium in LTC receive inadequate care and treatment. The purpose of this investigation is to estimate the prevalence of delirium in the LTC setting and to identify the natural history (i.e. onset, duration, and resolution), and risk factors for this illness. A longitudinal design, conducted in two phases, will be used. Phase I will consist of 30 days of follow-up (i.e., to measure period prevalence) and Phase II will consist of a one-year follow-up comparing mortality, rate of hospitalization, an in-house fall rates between delirium subjects and non-case subjects. A two-stage cluster sampling strategy will be used. The procedure for screening to identify cases will incorporate instruments with established psychometric properties, specifically the Confusion Assessment Method (CAM) and the NEECHAM. Baseline cognitive assessments will be completed on subjects using the Mini Mental Status Exam (MMSE). A board certified gero-psychiatrist consultant will review a random sample of both cases and non-cases so that sensitivity and specificity measures can be obtained for the algorithm. Numerous physiological measures will be taken including serum electrolytes, CBC, and urinalysis. Serum specimens will be analyzed at a central laboratory. Bedside urinary tract infection (IJTI) screens will be accomplished with a portable photometric urine analyzer and an ultrasound of the urinary bladder for post-void residual volume using a BladderScan BVT3000. Medication risk based on the duration and number of medications will be used to develop summary measures of delirium risk in consultation with a clinical Pharm D consultant. Total body water (TBW) will be estimated at the bedside with a multi-frequency Bioelectric Impedance Analysis (BIA) device. The ultimate goal is to provide accurate risk measures and which will lead to the development of effective delirium intervention strategies specifically designed for the LTC population.