Memory test ‘identifies Alzheimer’s early’
Doctors will be able to identify the initial signs of Alzheimer’s disease earlier thanks to a new 10 minute, picture-based memory test.
The iPad-based test will enable GPs to test patients in high street surgeries, rather than having to refer them to specialist clinics, which could drive up diagnosis rates.
Currently only 40 per cent of the 750,000 people with dementia in Britain receives any help or treatment, because the rest have not been diagnosed. This is partially because positively identifying the disease – in particular Alzheimer’s itself – can be difficult.
Scientists behind the new Cantab Pal test say it picks up early stage Alzheimer’s and a forerunner of dementia, called mild cognitive impairment (MCI), before existing tests, because it examines the part of the brain that starts deteriorating first, called the hippocampus.
It is tasked with remembering fleeting everyday details such as where one parked the car, or put one’s keys, a function called episodic memory, explained Prof Barbara Sahakian, a clinical neuroscientist at Cambridge University.
By contrast, the most widely-used cognitive test for dementia today, the mini-mental state examination (MMSE), examines a part which breaks down later in the course of Alzheimer’s, called the temporal neocortex, she said.
This stores learned – or ‘semantic’ – memory. Patients asked questions like “Who is the Prime Minister?” or requested to repeat three words back to the interviewer, such as ‘apple’, ‘penny’ and ‘table’.
However, this often underestimates the degree of Alzheimer’s in well educated people. It also only helps identify the disease when it has already caused significant brain damage.
With the new picture-based test, patients are asked to recall the location on the iPad screen of different symbols that flash up briefly.
The test gets progressively harder. Participants first have to remember where a single symbol flashed up, in one of six possible boxes, while at the end they are asked to recall where six symbols were.
Research indicates the test is 95 per cent accurate at correctly distinguishing healthy people from those with mild cognitive impairment, and at telling those with MCI from those with Alzheimer’s itself.
It identified people with cognitive impairment up to 32 months before they were officially diagnosed with Alzheimer’s, said Dr Andrew Blackwell, chief scientific officer of the spin-off company that has developed the test, called Cambridge Cognition.
If the test is adopted by GPs, it could mean far more people being prescribed drugs treatment.
In March the National Institute of Health and Clinical Excellence (Nice) changed its qualifying criteria for three drugs – Aricept, Reminyl and Exelon – enabling those with early-stage Alzheimer’s to get them on prescription. Before, patients had to exhibit moderate symptoms or worse.
Prof Sahakian believed the way forward was earlier treatment still: “We really want to be able to detect Alzheimer’s disease very early and halt it at the stage when people are still functioning well.
“We don’t want to be putting these drugs into people [only] when they have already declined.”
Dr Andrew Blackwell said the test was already registered as an approved NHS medical device.
It is currently being trialed by one health trust and the firm hopes to begin selling the test throughout the NHS next year, probably by licensing it out to health authorities or GP consortia.
The test has only been formulated to identify MCI and Alzheimer’s, the latter accounting for about 60 per cent of dementia cases.
Dr Anne Corbett, of the Alzheimer’s Society, said the test could help change the “appalling picture” of so many Alzheimer’s cases remaining undiagnosed, which condemned hundreds of thousands to suffer “without help, support or treatment”.
“However, it is too early to tell if it will prove to be a useable, effective and accurate tool for GPs,” she added. “We must now wait for the results of the trials to see if it could fit into the wider diagnostic process.”
– Stephen Adams