temporarily dialing up the amount of sugar in the mice’s
blood, amyloid production dramatically increased.^26 Young
mice that had their blood sugar doubled during a four-hour
“challenge” (the equivalent of eating a high-carbohydrate
meal by a person with poor glucose control) had a 25
percent increase in amyloid beta production, as measured in
their spinal fluid. Older mice were particularly vulnerable,
seeing a 40 percent increase from the same blood sugar
challenge.
Researchers noted that repeated surges of blood sugar,
such as what is common in type 2 diabetes, “could both
initiate and accelerate plaque accumulation.” They
concluded that plaques in the hippocampus “are likely
modulated by blood glucose levels.” The important
distinction, of course, is that what happens in rodent disease
models doesn’t always happen in humans. Regardless,
studies like this are important pieces in the puzzle for
discovering why higher glucose levels are strongly
associated with increased risk for dementia, even in people
without diabetes.^27
The Sour Truth about Sweet Fruit
Why would a sugar found naturally in fruit be so poorly
tolerated by modern humans? It doesn’t make intuitive
sense, until we consider the scarcity and seasonality of fruit
until a few short decades ago.