The Alzheimer's prion hypothesis is implausible, or at least incomplete. The proteins should spontaneously misfold at a small rate, followed by dementia 20-30 y

The Alzheimer's prion hypothesis is implausible, or at least incomplete. The proteins should spontaneously misfold at a small rate, followed by dementia 20-30 years later. The incidence at age 90 is something like 50%, and if we follow the exponential curve backwards, something like 0.5% of newborns should have tau prions, meaning several percent of teenagers should have early dementia. Instead the teenage dementia rate is vanishingly low, effectively zero. We would also expect clusters of Alzheimer's disease in young patients who were seeded by tissue contamination: recreational IV drug use, transplants, blood transfusions, etc. We do not observe this. The only obvious factor seems to be age. Something changes during aging that enables Alzheimer's disease. Before the change we are essentially bulletproof. After a steady increase sets in. I'm betting on some hormone being the culprit, possibly tied to a reactivated virus.