GLIAL-CELLS IN ALZHEIMERS-DISEASE - PREFERENTIAL EFFECT OF APOE RISK ON SCATTERED MICROGLIA

Reactive glial cells are consistently found in the brain tissue of Alz heimer's disease (AD) patients. Both clustered and scattered glial cel ls occur in AD brain. A number of clustered microglial cells, but not astrocytes, had a positive correlation with neurite plaque numbers, su ggesting that clustered microglial cells are uniquely associated with plaques whereas clustered astrocytes may have functions outside the pl aques as well. APOE epsilon 4, the major genetic risk factor for AD, h ad a dose-dependent effect to increase the numbers of scattered microg lial cells whereas the APOE risk showed no correlation with any of the clustered glial cells or scattered astrocytes. These findings raise t he possibility that the increased levels of scattered, but not cluster ed, microglial cells are the immediate response to APOE risk and might be primarily involved in AD pathogenesis.