Scientists warn that new drugs will require earlier diagnosis of Alzheimer’s

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Major improvements must be made in techniques for identifying future Alzheimer’s disease patients if medicine is to take advantage of drugs that could inhibit or halt their mental decline.

This warning was made last week by several senior scientists after the announcement by the pharmaceutical giant Eli Lilly that its drug, solanezumab, had been shown to stave off memory loss in patients with mild Alzheimer’s.

The discovery was hailed as hugely significant by some researchers because the drug is the first to provide evidence that it could slow the rate at which the disease damages patients’ brains.

But as other scientists warned last week, trials of solanezumab were carried out on individuals who have already displayed symptoms of Alzheimer’s and who would therefore have already suffered loss of brain function. To tackle the disease effectively, ways have to be found to diagnose those destined to get the disease before they suffer such a loss.

This point was stressed by Professor David Mann of Manchester University. “Reliable and relatively inexpensive disease predictive markers are urgently needed, whether these be blood, imaging or psychologically based.” Only then would it possible to test the real effectiveness of drugs like solanezumab – “to see whether they really do what it says on the label,” he said.

The trouble is that, at present, diagnosis of Alzheimer’s is still an imperfect science. “About 25% of diagnoses by doctors of early-stage Alzheimer’s are incorrect,” said Eric Karran, director of research for Alzheimer’s Research UK.

“Obviously that figure has to improve. Indeed, we have to develop tests that will allow us to make accurate diagnoses at even earlier stages of the disease, before there has been a loss of brain function.”

How that can be achieved is unclear, although Karran said new imaging techniques do make it easier for neurologists to spot a person affected by early-stage Alzheimer’s. “However, these techniques are currently expensive – costs can reach £1,000 to £2,000 a scan.”

Just identifying those who are going to get Alzheimer’s could therefore be a highly expensive process and will put new pressures on the health service.

“On top of that, we still do not know how much the pharmaceuticals companies are going to charge for their anti-dementia drugs once we have learned how to pinpoint those who should receive them,” added Karran.

The news about solanezumab comes as the Observer this week launches a page on its website dedicated to John’s Campaign which aims to help carers of Alzheimer’s patients. The fact that the new drug did produce statistically significant improvements in patients with mild Alzheimer’s has raised hopes that medicines can now be developed to delay the onset of the disease.

John’s Campaign to transform dementia care is gaining powerful support

Alzheimer’s is caused by the build-up of proteins, in particular one called amyloid, in the brain. These proteins form clumps or plaques which, scientists believe, trigger the disease’s symptoms of severe memory loss, confusion and disorientation. Solanezumab binds to specific, single molecules (called abeta) that aggregate to form amyloid in the brain. “That may explain its ability to slow the disease in mild cases,” said Karran. “In addition, there may be a natural loss of these small abeta molecules from amyloid plaques that would also be part of its therapeutic benefit.”

Further insights are expected next year when scientists complete a second trial of solanezumab on patients with mild Alzheimer’s. These studies already suggest scientists are closing in on the right target for Alzheimer’s drugs.

“From a scientific perspective, this study is exciting because it further validates the amyloid hypothesis ... and will therefore guide scientists working on more effective disease-modifying therapeutics,” said Dr Tara Spires-Jones of Edinburgh University.

Every year around 225,000 people are diagnosed with Alzheimer’s in the UKand, as Britain’s population ages, figures are destined to rise and place the health service under further strain. Any good news about the condition – however qualified – is therefore to be welcomed. As Alzheimer’s expert John Hardy, of University College London put it: “It’s a bit like a forecast of sunny weather: it raises hopes of good weather, but it does not mean that it is a certainty.”

■ One in six people over 80 have dementia.

■ Alzheimer’s disease is the most common form of dementia, affecting 62% of those diagnosed.

■ Two-thirds of the cost of dementia is paid by people with dementia and their families. Unpaid carers save the economy £11bn a year.

■ The UK spent £73.8m on dementia research in 2012-13, compared with £502.8m on cancer research.

■ There are 850,000 people with dementia in the UK, and the figure is set to rise to over a million by 2025

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