Estimating incidence of Alzheimer’s across the UK

There are estimates of the number of diagnoses on the Alzheimer’s Society website here :  I intially misinterpreted this map to be indicating rates of diagnosis, but this is not the case. It is indicating the difference between diagnosis rates across the UK.  The message the map appears to show is that diagnosis of Alzheimer’s is best in Scotland and Ireland, and worse in the South of the UK.

Accompanying the map is a table of registered diagnoses by healthcare region.  To determine incidence, I added populations from the UK, Scottish, Welsh and Irish statistics departments of relevant governement departments.

This first map is the registered diagnoses by UK region.  I have used Google Fusion tables to produce the graph.  Unfortunately, I couldn’t find geographical region data for the UK that included Northern Ireland.  Northern Ireland’s incidence was 6.56 per 1000 individuals, slightly higher than that of the South West of the UK (6.44 per 1000), and not as high as Scotland (7.84 per 1000).

Click here to open map of UK Alzheimer’s incidence.
(Click on the “Map of Geometry” tab)

Here’s a table of the data:

Dementia diagnosis/1000 Estimated Dementia Incidence/1000 % pension age
North East 6.38 12.84 20.1
North West 5.98 12.20 19.4
Yorkshire & the Humber 6.04 12.43 19.1
East Midlands 5.73 12.84 19.7
West Midlands 5.43 12.63 19.7
East of England 5.47 13.66 20.2
London 3.81 8.55 13.8
South East 5.73 13.68 19.9
South West 6.44 15.74 22.5
Wales 5.61 14.56 22.0
Northern Ireland 6.56 10.42 17.7
Scotland 7.84 12.18 20.0

The middle column includes an estimate of undiagnosed Alzheimer’s.  When we plot these data, the picture changes somewhat.

Click here to open a map showing indicence including estimated undiagnosed Alzheimer’s.
(Click on the “Map of Geometry” tab)

In this map, Scotland seems to have comparable rates of Alzheimer’s. This is because the Alzheimer’s Society estimates of undiagnosed Alzheimer’s are much lower for Scotland (and for Northern Ireland). The diagnosis rate in Scotland is estimated at 63.0% versus around 45% for the rest of the UK (Northern Ireland also has a diagnosis rate of 64.4%).

In both maps, London has a significantly lower rate of Alzheimer’s than the rest of the country. This is because there are less older people in London compared to the UK:

Click here for a map of the percentage of people on pensionable age (65M/60F).
(Click on the “Map of Geometry” tab)

In summary, it seems as if the incidence of Alzheimer’s is mostly related to how many older people live in a region. However, this is very dependent on the estimates of those with undiagnosed Alzheimer’s, which is difficult to estimate (as it is essentially missing data).