Silent Damage First: Alzheimer's Disease Could Have Two Phases

THURSDAY, Oct. 17, 2024 (HealthDay News) -- Alzheimer’s disease might damage the brain in two distinct phases, a new study suggests. An early phase that occurs slowly and silently appears to lay the groundwork for a second, more widely destructive phase of Alzheimer’s, according to sophisticated brain scans.

“The results fundamentally alter scientists’ understanding of how Alzheimer’s harms the brain and will guide the development of new treatments for this devastating disorder,” said Dr. Richard Hodes , director of the National Institute on Aging. Previous studies have suggested that the damage caused by Alzheimer’s occurs in several stages, characterized by increasing levels of neuron death, inflammation and accumulation of toxic proteins in the brain.

But these results indicate there really are just two phases of Alzheimer’s, with most of the traditional symptoms and brain damage happening rapidly during the second phase, researchers said. Brain scans of 84 people suggest that the first phase occurs prior to any memory problems that might develop. During this phase, damage occurs to a type of brain cell called an inhibitory neuron that might trigger the neural problems that underlie Alzheimer’s, researchers said.

Inhibitory neurons send calming signals to other cells, researchers said. Losing these cells might strip the brain of a key level of protection. The first phase also is marked by a slow accumulation of toxic protein plaques, activation of the bra.