A different view of inflammation in Alzheimer's disease
Lane Simonian
Posted: Sunday, March 5, 2017 10:31 PM
Joined: 12/12/2011
Posts: 4066
Microglia (the brain's main immune cells) are likely over-activated during the early stages of Alzheimer's disease leading to inflammation but damaged as the disease progresses:
New research suggests that Alzheimer’s disease (AD) could be caused by the degeneration of microglia, the cells in the central nervous system that normally protect neurons...
This new hypothesis challenges the theory that AD is the result of amyloid protein deposits in the brain that trigger an inflammatory reaction. According to this theory, the inflammatory response activates microglial cells to produce toxic substances that in turn cause neurons to degenerate. This inflammation theory has been implicated not only in AD but in other neurological diseases, including Parkinson's disease, amyotrophic lateral sclerosis (ALS), and Huntington's disease.
"If people are claiming that these activated microglia kill neurons by producing toxins of various kinds, then I should expect to see these activated microglia right next to the dying neurons," said lead author and microglia expert Wolfgang J. Streit, PhD, from the department of neuroscience at the McKnight Brain Institute at the University of Florida College of Medicine, in Gainesville.
"But when I looked in those regions, I couldn't find a single activated microglial cell," he told Medscape Neurology. "What I found instead were microglial cells that were breaking apart, fragmenting into many little pieces."
These observations might help explain why anti-inflammatory drugs do not seem to prevent or diminish dementia, he suggests. And if borne out, they could result in a reevaluation of current treatment approaches for AD.
Inflammation may play a role in Alzheimer's disease (activated microglia, for instance, add to oxidative stress), but its role may decline as the disease continues. Furthermore, the damage done to microglia by oxidative stress may prevent them from removing toxins from the brain.
