Neurodegenerative diseases and Alzheimer's disease (AD) in particular, are among the major health concerns of the elderly in industrialized societies. The cause of AD is unknown and no disease-modifying treatments are available. The disease is characterized clinically by a progressive dementia and pathologically by the accumulation of protein aggregates in the brain and a profound loss of nerve cells. It has also become clear recently that local immune responses are activated in the AD brain and may have a role in the disease. Our laboratory uses genetic mouse models to understand the disease process and to identify potential therapeutic targets.