The Claim
The plasma Aβ42/Aβ40 ratio is significantly reduced approximately 11.5 years before the clinical onset of mild cognitive impairment in individuals who later develop Alzheimer’s disease, while remaining stable in individuals who develop non-Alzheimer’s cognitive impairment.
What the research says
Supports is higher
Support is ahead, but a single strong opposing study can change this.
These are independent scores, not a percentage. Higher-grade studies count more, so a single strong opposing study can outweigh several weaker ones.
In people who will later develop Alzheimer’s disease, the ratio of two amyloid proteins in the blood drops about 11.5 years before memory problems appear. This change does not occur in people who develop other types of cognitive decline.
See the scientific wording
The plasma Aβ42/Aβ40 ratio becomes abnormal approximately 11.5 years before clinical onset of mild cognitive impairment in individuals who develop Alzheimer’s disease, reflecting early amyloid pathology, but does not change in individuals who develop non-Alzheimer’s cognitive impairment.
In the brain, amyloid-beta 42 is cleared more slowly than amyloid-beta 40, so it builds up first and sticks together into clumps. As more amyloid-beta 42 gets trapped in the brain, less of it flows into the blood, making the ratio of amyloid-beta 42 to amyloid-beta 40 in the blood drop. This drop happens years before memory problems start, and only in people whose brains start forming these clumps.
What the research says
1 studyStudy: Plasma biomarker trajectories across Alzheimer’s clinical onset: a 17-year prospective study
This blood test that measures two amyloid proteins shows abnormal changes about 11.5 years before memory problems start in people who will get Alzheimer’s, but stays normal in people who get other kinds of memory problems — just like the claim says.
Score breakdown, mechanism chain, raw evidence, ideal studies needed & 1 supporting studies
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.