The taxi-driving Alz patients may overwhelmingly die of something that leads to physicians not listing Alz as a cause of death. If taxi driving is loaded in such a way that Alz presents significant challenges (eg loss of income), that could be the case.
One easy way to confirm this is to look at the impact of GPS on this + whether London taxi drivers get less frequent Alzheimer’s than other cities/countries that don’t have the same requirements and complexities.
