And another one bites the dust...

Neuroinflammation is part of the pathology of Alzheimer's disease.  The brain's immune cells -- the microglia -- participate in inflammation when they are trying to fight infection or rid the brain of debris from dead cells.  Accumulation of the debris and other unwanted substances (like beta amyloid) occurs as Alzheimer's disease progresses and is part of the disease process. 

Inflammation has a protective function, but it also causes collateral damage to other brain cells.  (We discussed this briefly on May 8, 2019 and on September 12, 2019.)  Therefore, diets thought to be good for Alzheimer's disease exclude foods that aggravate inflammation -- generally processed foods, including refined sugar and refined flour.  (We discussed this on March 2, 2019.) 

Unfortunately, non-steroidal anti-inflammatory drugs (NSIDs) may reduce inflammation in the brain (as in headaches), but they do not improve cognition for people with Alzheimer's disease.  So researchers were not terribly surprised when recent research found that the antibiotic minocycline also did not improve cognition in people with mild Alzheimer's disease.  Testing with mice and rats found that it could slow neuronal death and promote the generation of new neurons in the hippocampus, but a two year test on humans failed to show improved cognition.  The thinking was that the antibiotic (a derivative of tetracycline) reduced neuroinflammation, at least in the rats and mice.  So maybe it could disrupt the process by which inflammation was contributing to the progress of Alzheimer's disease in humans.

Especially after what happened with the NSIDs, no one seemed to be surprised at this failure.  They seemed more interested in this test as a model for testing other approved drugs that may be repurposed to fight Alzheimer's or other diseases.