Parkinson's

Conventional wisdom suggests that occupations associated with low socioeconomic status – such as construction, extraction and maintenance jobs – would be linked to the greatest number of ALS and Parkinson's deaths because of workers' environmental exposures to chemicals. But the CDC found the opposite to be true.
Pregnant women are advised to avoid cat litter boxes — so they don't get infected with Toxoplasmosis gondii, which can cause birth defects. Recent research also suggests that this parasite may also be linked to neurodegenerative diseases such as Parkinson's and Alzheimer's.
Two large meta-analyses in JAMA shed light on the link between Alzheimer s disease and amyloid beta (A-β). The key findings indicate that it is likely to take up to 30 years of amyloid deposition before clear signs of dementia are manifest but such deposits are not diagnostic.