Abstract
BACKGROUND: Recent studies have revealed an inverse epidemiological correlation between Alzheimer's disease (AD) and cancer - patients with AD show a reduced risk of cancer, while cancer survivors are less likely to develop AD. These late discoveries in human subjects call for explorative studies to unlock the underlying biological mechanism, but also may shed new light on conceptual interrogation of the principal pathogenic players in AD etiology. DISCUSSION: Here we hypothesize that this negative correlation reflects a rebalance of biosynthetic propensity between body systems under the two disease statuses. In normal condition the body cellular systems are maintained homeostatically under a balanced cell degenerative vs. surviving/regenerative propensities, determined by biosynthetic resources for anabolic processing. AD pathogenesis involves neurodegeneration but also aberrant regenerative, or reactive anabolic, burden, while cancer development is driving by uncontrolled proliferation inherent with excessive anabolic activity. The aberrant neural regenerative propensity in AD pathogenesis and the uncontrolled cellular proliferative propensity in cancer pathogeneses can manifest as competitive processes, which could result in the inverse epidemiological correlation seen among the elderly. SUMMARY: The reduced prevalence of AD in cancer survivors may implicate a strong impact of aberrant neural regenerative burden in neurodegeneration. Further explorative studies into the inverse correlation between AD and cancer should include examinations of the proliferative propensity of tumor cells in AD models, and the development of AD-like neuropathology in cancer models as well as following anti-proliferative drug treatment.