Alzheimer's disease (AD) is a common cause of dementia, resulting from accumulated beta-amyloid protein deposits in the brain. As the population ages the incidence of AD is also on the rise. The incidence is very high in the developed countries where life expectancy is high, but it is also rising rapidly in the developing countries. Caring for patients suffering from AD is a major economic burden. The mechanisms underlying the neuropathology of AD are slowly being unravelled. Here we explore the many models and theories, which have been proposed over the years. We then discuss a potential therapeutic agent, vaccinia virus complement control protein (VCP), involved in modulating the complement system in AD. VCP has been shown in in vitro studies to block the complement activation caused by the beta peptide. Traumatic injuries to the brain are well known risk factors associated with the development of AD. VCP can also enhance functional recovery resulting from traumatic brain injury and may be able to slow the progression of traumatic brain injury to AD. Here we describe strategies for testing this hypothesis and evaluating other agents such as VCP.