How stress triggers Alzheimer's disease decoded

Chronic stress elevates steroids in the brain which inhibit cognitive activity and lead to an increased risk for Alzheimer's disease, a new study has found.
Researchers from Umea University, Sweden found that chronically elevated levels of allopregnanolone, a steroid seen in the brain during stress, accelerated Alzheimer's in two mice models.
The Alzheimer's mice responded with impaired learning and memory. They had also increased brain levels of beta-amyloids, the proteins that form plaques in Alzheimer's disease.
Alzheimer's is a neurodegenerative disease that destroys brain cells. Symptoms include having difficulty remembering things, making decisions and performing everyday activities.
One of the hallmarks of the disease is the accumulation of protein amyloid plaques between nerve cells in the brain.

Beta-amyloid is a protein fragment that normally is broken down and eliminated in a healthy brain. With Alzheimer's, these fragments form hard, insoluble plaques.

The study found that high levels of beta-amyloids corresponded to dysfunction among brain synapses, the connections between nerve cells.
This was seen after a period of chronically elevated levels of allopregnanolone, but not after placebo treatment.
The effects were identified early in the disease development when the animals normally have intact memory function.