Stress -> Alzheimers

Chronic stress has long been linked with neurodegeneration. Scientists at the 

University of Southern California (USC) have now found a mechanism:chronic stress (physical or mental) causes overexpression of the RCAN1 gene, in turn leading to neurodegenerative disease.

The mechanism involves these steps:

1. Chronic overproduction of RCAN1 causes hyperphosphorylation of tau proteins in the brain. (In a healthy person, the RCAN1 gene helps cells cope with stress.)

2  Tau proteins stabilize microtubules, which are like scaffolding, used to build the brain’s neurons. Previous research has shown that when the tau protein binds too much phosphate (a process called hyperphosphorylation), it forms snarls that prevent the brain’s signals from effectively traveling.

3. These neurofibrillary tangles eventually choke the life out of neurons, killing off brain function a tiny piece at a time in what is outwardly recognized as degenerative brain disease.

The researchers suggests that overexpression of RCAN1 is also connected to Amyloid beta (overproduction of the Amyloid beta peptide), a competing theory of neurodegeneration.

Coffee protects against Alzheimer’s, in spite of its alertness-inducing caffeine. The fact that this condition (too much RCAN1) causes lesions in the brain doesn’t mean that RCAN1 is bad (it’s not;
The researchers have also shown a connection between too little RCAN1 production and Huntington’s disease.
), or that a little stress is bad (it’s not). But it does provide some confirmation of what was already pretty well known: chronic high stress levels are incredibly harmful to any animal’s health. I’d like to understand what’s meant by “stress” more precisely, as what I believe about it seems almost tautological.