This article appears as part of the Inside the NHS newsletter.

In the space of nine months the world has gone from having no drug treatments for Alzheimer's, to having two.

After decades where patients had nothing except medications to manage their symptoms, clinical trials have shown that both lecanemab and now donanemab significantly slow the progression of the disease.

In a country such as Scotland, with an ageing population, this is undoubtedly good news. The real challenge, however, is how the NHS can adapt to this new landscape for Alzheimer's.

How many people have Alzheimer's?

It might come as a surprise, but we don't know how many people in Scotland actually have Alzheimer's disease.

As of 2015, it was estimated that there were "up to 90,000 people in Scotland affected by dementia", according to Public Health Scotland. That is nearly one in every 50 people living here, and it's a number that is only set to climb.

That estimate was based on population screening studies carried out in parts of Europe around 15 years ago, however, which were then used to extrapolate what the prevalence might be for Scotland.

In 2016, the Scottish Government tried to get a more accurate projection for incidence. It gathered data on diagnoses from three health board regions – Lanarkshire, Greater Glasgow and Clyde, and Ayrshire & Arran – and used this to predict that, by 2020, we should have been diagnosing 19,473 people a year with dementia across Scotland as a whole.

This was said to give an "accurate reflection of Scottish rates without relying on estimates calculated from data gathered in other nations", but even then was complicated by differences in data collection between health board regions.

Furthermore, dementia and Alzheimer's disease are not one in the same.

Dementia – characterised by a decline in cognitive functions such as memory, reasoning and language – is a symptom of Alzheimer's disease, but there are other forms such as Lewy Body and vascular dementia.

Roughly 60-70% of dementia cases are believed to be caused by Alzheimer's.

Accurate diagnosis will be vital, however, as lecanemab and donanemab are only effective in Alzheimer's.

The Herald:

Early diagnosis


Until now, there was little incentive to detect Alzheimer's disease at an early stage because nothing could be done to treat it.

If lecanemab and donanemab are approved by UK regulators that will have to change – and that's a big problem for the NHS.

Both drugs are most effective when administered early, but at present fewer than 1% of patients seen by dementia clinics across the UK have an accurate diagnosis of Alzheimer's disease.

There are only two methods of correctly identifying it. One is by a lumbar puncture to extract spinal fluid which can then by analysed for the amyloid protein biomarker which signals the disease, but this is invasive.

The second is a brain imaging using a PET scanner, but the UK has less than half the European average of PET scanners per million people.

In Scotland, the NHS has four PET centres – in Glasgow, Edinburgh, Aberdeen and Dundee – but they are already close to full capacity just from dealing with 6,500 specialist cancer scans annually, at a cost of around £1000 per scan.

Yet if estimates are correct, we should be diagnosing around 12-13,000 Alzheimer's cases a year by now.

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Any push to rapidly expand the PET capacity through additional machines, however, would be hindered by the very limited availability of staff skilled to use them.

Then there is the question of who we prioritise for screening in the first place. Like cancer, NHS resources would have to be allocated on a delicate risk-benefit calculation to individuals considered to be at the highest risk of the Alzheimer's who also have the most to gain from being diagnosed early.

Are there alternatives?

When the lecanemab results were unveiled last November, Professor John Hardy – an expert in the molecular biology of neurological disease at University College London – said he could envisage a "brave new world" where people would receive "cholesterol-style blood tests" on their 60th birthdays to check their amyloid levels.

Reliable diagnostic blood tests would be a big help, and they do appear to be moving closer.

As of this week, patients at private clinics in Hong Kong can pay for a PlasmaskAD blood test which will be used to provide a personalised risk score for Alzheimer's, ranging from low to high.

It is based on research showing that the amyloid proteins in the blood can be used to diagnose the presence and progression of Alzheimer's disease.

This is important because the time lag between disease onset and the start of symptoms, in the form of cognitive impairment, is thought to be anything from 10 to 20 years.

In the UK, large trials of these kinds of blood tests are already underway, including a £5 million project funded by the Alzheimer Society and Alzheimer Research UK exploring how they could be integrated into the NHS to speed up early diagnosis and prescribing.

"This is a time to be optimistic," said Susan Mitchell, head of early detection at Alzheimer's Research UK.

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