Psychiatric disturbances affect as many as 90% of patients with Alzheimer's disease (AD) and are a major focus of treatment. Depression is one of the most frequent psychiatric complications of AD, affecting as many as 50% of patients. In this context, depression is a significant public health problem that has a series of serious adverse consequences for patients and their caregivers. There has been little research into the course or treatment of depression associated with AD. This is in part due to the absence of validated operational criteria for defining depression in AD. Recently, the National Institute of Mental Health (NIMH) convened an expert consensus panel to develop draft criteria for depression of Alzheimer's disease (NIMH-dAD) and to establish research priorities in this area. This article provides an overview of recent knowledge with regard to depression in AD with a special emphasis on its treatment. We conclude with recommendations for further research in this area.