Inflammation and AD

Contributed by: Michael Rafii, M.D., Ph.D - Director of the Memory Disorders Clinic at the University of California, San Diego. ______________________________________

Microglia are the housekeepers of the brain, digesting foreign bodies and protecting neurons from damage. In culture, these cells are well known for ingesting amyloid-β, and in Alzheimer disease they surround amyloid deposits.

But in a study published in the October 18 Nature Neuroscience online, researchers in Germany have almost completely removed microglia from the brains of transgenic mice, and to their surprise they found absolutely no change in plaque size or number.

This leads to the hypothesis that the microglia may surround the plaques, but are essentially protecting the rest of the brain and not involved in modifying, depositing, or removing the plaques. The study also raises the possibility that cell-mediated inflammation does not promote more amyloid or more Aβ, which has been a hypothesis for a long time.