[The role of apolipoprotein E in the pathogenesis of Alzheimer disease].

Alzheimer disease (AD) is by far the most common cause of dementia in humans. Massive accumulation of senile plaques and neurofibrillary tangles are characteristic neuropathological manifestations of the disease. Recent investigations have revealed the presence of apolipoprotein E (apoE) in these structures. Furthermore, APOE4, a specific allele of the apoE gene, is frequently associated with sporadic AD and late-onset familial AD. Now, APOE4 has been established as being a major risk factor for AD. Although apoE is one of numerous plasma lipoproteins, it is of particular interest because, unlike other lipoproteins that are mainly synthesized in the liver, apoE is also synthesized in astrocytes and oligodendrocytes in the central nervous system. Furthermore, apoE plays an important role in the regeneration and degeneration of neurons. Recent studies have indicated the possibility that APOE4 accelerates the deposition of amyloid beta protein, which is a major component of senile plaques in AD brains.