I've been following, at a distance, the developments of AD research.
The culprit is not Amyloid or Tau in themselves, but their misfolded variants, which have prion-like properties: they can't be degraded (and thus accumulate), and turn their respective healthy variants into their pathological counterparts.
Misfolded Tau is intracellular, but it is known to propagate from cell [0,1], causing havoc on its way since its accumulation is sufficient to cause neurodegeneration.
Misfolded Amyloid may not be toxic in itself, but it probably acts as a misfolding template for Tau (it does in vitro) [2].
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.
The point is, that having to struggle against the mainstream is not strong evidence in either direction. The difference is, the crackpots don't have any other strong evidence, either.
"Science is politics," he says. "And the politics of amyloid won."
This quote is just the kind of thing the public need to read to improve their confidence in the scientific method.
There needs to be a better distinction between established scientific knowledge and the funding decisions for research of unresolved questions. In other words, Science HAS_A Politics, not IS_A Politics.
But politics and money typically do not dictate scientific results, as evidenced by the failure of the amyloid-targeted trials mentioned in the article.
11 comments
[ 3.2 ms ] story [ 34.6 ms ] threadI've been following, at a distance, the developments of AD research.
The culprit is not Amyloid or Tau in themselves, but their misfolded variants, which have prion-like properties: they can't be degraded (and thus accumulate), and turn their respective healthy variants into their pathological counterparts.
Misfolded Tau is intracellular, but it is known to propagate from cell [0,1], causing havoc on its way since its accumulation is sufficient to cause neurodegeneration.
Misfolded Amyloid may not be toxic in itself, but it probably acts as a misfolding template for Tau (it does in vitro) [2].
--
0. http://www.ncbi.nlm.nih.gov/pubmed/22365544
1. http://www.ncbi.nlm.nih.gov/pubmed/19282288
2. http://www.ncbi.nlm.nih.gov/pubmed/22965142
These may not be the best sources for these very points they're the first relevant papers I could find on the spot.
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.
1. http://opinionator.blogs.nytimes.com/2012/09/25/bittman-is-a...
This may be right, but it's also an argument used by crackpot theorists.
This quote is just the kind of thing the public need to read to improve their confidence in the scientific method.
There needs to be a better distinction between established scientific knowledge and the funding decisions for research of unresolved questions. In other words, Science HAS_A Politics, not IS_A Politics.