Recent research has also highlighted new mechanisms
by which chronic stress can impair your long-term brain
health. Chronic stress was shown to actually activate the
immune system of the brain, producing inflammation almost
as if the brain were responding to stress as an infection.
Inflammation is the cornerstone of many neurodegenerative
diseases, as I’ve mentioned throughout this book. But
recently, chronic exposure to stress hormones was
connected to the hallmark plaque that characterizes
Alzheimer’s disease. Long-term administration of cortisol
was shown to reduce levels of insulin-degrading enzyme
(IDE) in the brains of monkeys.^27 IDE is responsible for
breaking down insulin in the brain as well as amyloid beta—
the protein that clumps together to form the plaques
characteristic of Alzheimer’s disease. (Revisit page for a
primer on IDE.)
As you can see, chronic stress is a major threat to our
cognitive health. But not all stress is created equal! In the
following chapter, we will see how one particular kind of
stress may be your brain’s best friend.
FIELD NOTES
Sleep is sacred—it keeps your hormones healthy,
helps your brain better regulate your emotions, and
can even help you lose weight.
Sleep is also when your brain cleans itself, offering a