Physicians increasingly are called on to provide primary care for the growing population of people with Alzheimer-type dementia. However, little attention has been paid to the care of nondementia illnesses in this group of patients. To illustrate how presence of dementia can alter the risk-benefit ratio of treatment of a common medical problem, we present a case study in which a patient with dementia developed disastrous adverse effects to a drug commonly used to treat osteoporosis. This case and 2 composite vignettes illuminate how presence of dementia should influence the decision-making process for treatment of nondementia illnesses. We address issues such as decreased decision-making capacity, problems with reporting adverse effects, decreased cognition leading to problems with treatment adherence, and the role of screening and basic questions about acceptable burdens of treatments in patients with limited prognosis. We suggest ways to improve communication with patients with dementia in an effort to minimize complications and improve care, as well as policy changes to include patients with dementia in clinical trials. JAMA. 2000;283:3230-3235