A new blood test that can diagnose  15 years before the disease appears will be available in the US within days.

Patients will be able to order the $500 ALZpath Dx test — which works by looking for a danger protein in the blood — through their doctor.

It is not set to be covered by health insurance because the test has not yet been recommended by an official US health body.

But research has shown the mail-in test is just as accurate — but much faster — than current gold-standard methods which involve lengthy appointments and drawing fluid from inside the spinal cord.

Experts have heralded the swab as a gamechanger, saying it will make Alzheimer's as easy to diagnose

 as 'high cholesterol'. 

A new blood test for Alzheimer's  is so simple experts say patients could expect results within 'days', rather than the years it currently takes to get a diagnosis (stock image)

But others have raised concerns about using the test to spot the disease among people with no symptoms, saying many may have markers of the condition .

Dr Andreas Jeromin, who is the chief scientific officer behind the test, told DailyMail.com: 'Our goal, and we have reached the first milestone with the launch of ALZpath Dx, is to provide access to a diagnostic tests for Alzheimer's.

'This is really something that patients and physicians need and want, so we really want to make these tools available.

'What physicians really need is a blood-based biomarker which can be easily drawn, potentially at home, and easily run and the results returned to the physician.'

Patients will have their blood drawn by physicians, before samples are sent to the NeuroCode lab in Washington state — which can run hundreds of tests per day.

There are also talks underway to start running the tests at three to four other labs across the Mid-West and on the East coast.

Patients can order the tests from anywhere in the US via their doctors.

The test — developed by California-based ALZpath — takes a few hours to complete with results then sent back to a physician. Blood samples can take days to arrive, depending on from where in the US they are sent.

The test does not need to be approved by the Food and Drug Administration (FDA).

About 6.7million Americans have Alzheimer's, although this figure is expected to rise to 13million by 2050 

Dr Jeromin said they are developing plans to offer the test in hospitals, where it could be completed in as little as 30 minutes, but this would require FDA approval.

He said they have now begun working with the FDA to approve this version of the test, but do not expect it to be available until 2025 or 2026.

The test is currently meant for older adults who already have symptoms of Alzheimer's or are concerned they may have the condition.

Dr Jeromin said they are working on a separate version that would indicate how likely someone is to develop the debilitating disease.

Swedish researchers said the test works by analyzing the levels of blood biomarker p-tau217, which corresponds to levels of tau and amyloid in the brain.

These proteins start to build up in the brain ten to 15 years before symptoms appear.

And they are thought to be behind Alzheimer's disease because they can form clumps in the brain which are believed to disrupt communication between cells.

In a study in Sweden on 786 people, they found the test was 97 percent accurate at predicting Alzheimer's disease.

That is comparable to the current more expensive tests available including spinal taps, which involve taking fluid from the spine, and brain scans.

Experts say the new test is set to 'revolutionize' diagnosis and could have 'hugh implications' for future treatments, speeding up diagnosis and clinical trials.

They were about 66 years old on average, the scientists said, and a third had signs of memory loss.

The scientists then grouped participants into being very likely or very unlikely to develop the condition.

Around a fifth of participants were also placed in the middle, and told they would need further tests — such as a spinal tap — to confirm their Alzheimer's status.

The findings, published in the journal JAMA Neurology, show that the approach was 97 percent accurate.

Professor David Curtis, an honorary professor at the UCL Genetics Institute in the UK, said the findings could have 'huge implications' for how Alzheimer's is managed.

'Everybody over 50 could be routinely screened every few years, in much the same way as they are now screened for high cholesterol,' he said.

'It is possible that currently available treatments for Alzheimer's disease would work better in those diagnosed early in this way.

'However, I think the real hope is that better treatments can also be developed.

'The combination of a simple screening test with an effective treatment for Alzheimer's disease would have a dramatic impact for individuals and for society.'

About 6.7million people in the United States have Alzheimer's disease, although this is expected to rise to more than 13million by 2050.

The condition affects around six in ten people living with dementia.

Memory problems, thinking and reasoning difficulties and language problems are common early symptoms of the condition, which then worsen over time.