> we don't see spouses getting PD or AD often

Actually it may seem so [1], though still there is not any conclusive evidence to support a transmission hypothesis really as all this could be due to increased stress and such factors. Also, brain surgeons' increased risk of AD and more reports of associated risks with regard to contamination from brain operations [2] (similar to the article's ones) provide more indications that such a hypothesis is not completely implausible. Though also far from strongly supporting it or anything, as there is no proper experiment design with control groups etc to make better conclusions.

[1] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2945313/ [2] https://www.medicaldesignandoutsourcing.com/report-suggests-...