Image of brain from York, believed to be part of a ritual sacrifice
A 2,000 year old brain was discovered in York and the announcement recently hit the wires. It would be fascinating to see if the brain shows any signs of amyloid accumulation and whether or not the individual was APOEe4 positive, if it could be extracted from the DNA.
Probably not, as DNA extraction of soft tissues is notoriously fraught with difficulties, such as contamination from the modern context, and any dried blood recovered may have degraded.
Early speculation suggests that the individual, dating to around 0 or the beginning of the Common Era (C.E.), was sacrificed and placed into a peat bog, as part of a religious ceremony dating back to Druidic practice. In this era, the Britons were self-governing and independent. Other recovered bodies in the U.K. and Northern Europe have shown evidence of similar treatment.
One scholarly speculation, that lead poisoning from pipes and lead-treated ceramic vessels caused widespread dementia in the first few centuries of the common era has been shown as fallacious, since such pipes would have been used only by a small fraction of the population and, according to hydrologists, dissolved calcium carbonate (lime) deposits from the water sources and vessels would have precipitated on any exposed lead surfaces, creating a molecular barrier.
Links for background:
Peat bog burials in Northern Europe
Druidism and Sacrifice
Lead pipes + ancient dementia