[dubfan]

As a resident of Washington the first thing that comes to mind is the difference in climate between the west and east. The eastern part of the state is mostly semi-arid, nearly desert in some areas.

I've heard we also have one of the highest rates of multiple sclerosis in the US, but I'm having a hard time finding good data on that.

[erichurkman]

It could also be something innocent, like a large treatment center or palliative care facility.

That is, unless the data is meticulously groomed to report the patients' county/state of origin.

[ekianjo]

I contacted Dr Doraiswamy (a well known Alzheimer specialist) and he could not think of any other reason than "higher rate of APoE4 genotype due to greater Scandinavian heritage". He also suggested this could be coming from the way the death ratio is calculated "ie the denominator of deaths to all other causes is lower due to better diet".

I'll see what I can find.