Researchers call them "betwixt" diseases, conditions that defy easy categorization (and, presumably, easy diagnosis and treatment). That was the position of those attending the 9th International Conference AD/PD in March 2009 in Prague. Rather than uncomfortably ignore the conditions' common elements, researchers explored explicitly the extensive overlap between Alzheimer and Parkinson diseases (and also the frontotemporal dementias). This nine-part series describes the context of the discussions and where they may lead.
Read more about it here.