The association of herpes simplex virus and Alzheimer's disease: a potential synthesis of genetic and environmental factors.

The chronic and sporadic nature of Alzheimer's disease (AD), in which the majority of presenting cases are over 65 years of age, suggests that compounded injury or long-term exposure to environmental factors is involved in the aetiology, rather than inherited genetic alterations. Great hope has been placed on identifying a causative infectious agent that would present the potential for therapeutic or preventative vaccines or drugs. Although not the sole causative agent, herpes simplex virus type 1 has been the most clearly established pathogen to be associated with AD development to date. Recent advances have begun to suggest mechanisms by which this ubiquitous, neurotropic pathogen may predispose an individual to the development of AD. Such progress should ultimately lead to therapeutic strategies that limit predisposing neurological damage and potentially reverse the process, increasing the quality and quantity of life in this patient population.