Hedi

Almost surely there will be no such sharp dividing line. "Regular" chemistry and engineering will probably not get you very far; biochem might be a bit better.

I don't think the OP remembers the lukewarm response to her last inquiry.

"Alzheimer’s disease (AD), the leading cause of dementia worldwide, is characterized by the accumulation of the β-amyloid peptide (Aβ) within the brain along with hyperphosphorylated and cleaved forms of the microtubule-associated protein tau. Genetic, biochemical, and behavioral research suggest that physiologic generation of the neurotoxic Aβ peptide from sequential amyloid precursor protein (APP) proteolysis is the crucial step in the development of AD."...

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3174086/

The cause and cure for Alzheimer's is not known....even diagnosis is difficult....

..."Amyloid plaques are found in the spaces between the brain’s nerve cells. They were first described by Dr. Alois Alzheimer in 1906. Plaques consist of largely insoluble deposits of an apparently toxic protein peptide, or fragment, called beta-amyloid.

We now know that some people develop some plaques in their brain tissue as they age. However, the AD brain has many more plaques in particular brain regions. We still do not know whether amyloid plaques themselves cause AD or whether they are a by-product of the AD process. We do know that genetic mutations can increase production of beta-amyloid and can cause rare, inherited forms of AD (see "Genes and Early-Onset Alzheimer’s Disease" for more on inherited AD)."...

https://www.nia.nih.gov/alzheimers/publication/part-2-what-happens-brain-ad/hallmarks-ad