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* Fatal brain-wasting disease has no effective treatments
* Experts say drug failures may be due to late trials
* Predictive test could find people before disease sets in
* Shares in Proteome Sciences, involved in work, jump 12 pct (Adds Proteome Sciences stock move)
By Kate Kelland
LONDON, July 8 (Reuters) - British scientists haveidentified a set of 10 proteins in the blood that can predictthe onset of Alzheimer's and call this an important step towardsdeveloping a test for the incurable brain-wasting disease.
Such a test could initially be used to select patients forclinical trials of experimental treatments being developed totry to halt progression of Alzheimer's, the researchers said,and may one day move into routine use in doctors' clinics.
"Alzheimer's begins to affect the brain many years beforepatients are diagnosed (and) many of our drug trials failbecause by the time patients are given the drugs the brain hasalready been too severely affected," said Simon Lovestone ofOxford University, who led this work from King's College London.
"A simple blood test could help us identify patients at amuch earlier stage to take part in new trials and hopefullydevelop treatments," he said.
Shares in biotech company Proteome Sciences, whichco-authored the study with scientists from King's College,jumped 12 percent on the news on Tuesday morning.
Alzheimer's is the most common form of dementia, abrain-wasting disease which in 2010 was estimated to be costingthe world $604 billion a year. The fatal disease affects 44million people worldwide, with the number set to triple by 2050,the campaign group Alzheimer's Disease International says.
Several big pharma firms including Roche, Eli Lilly, Merck & Co and Johnson & Johnson, arepursuing various approaches to get to the root cause ofAlzheimer's and try to find treatments to halt its progression.
Yet over the past 15 years, more than 100 experimentalAlzheimer's drugs have failed in trial. Lovestone and otherexperts believe this may be because drug trials are conductedtoo late, in patients whose condition has already gone too far.
A predictive test for use before people develop symptomswould help researchers select the right people for drug trials,and help show whether the experimental drugs are working.
SEARCH FOR ALTERNATIVE TEST
Previous studies have found that PET brain scans and testsof lumbar fluid can be used to predict the onset of dementiafrom people with a less severe condition known as mild cognitiveimpairment (MCI), but these tests are expensive and invasive, soscientists are keen to develop a cheaper, simpler blood test.
MCI includes problems with day-to-day memory, language andattention. It can be an early sign of dementia, or a symptom ofstress or anxiety.
Around 10 percent of people diagnosed with MCI developdementia within a year. Apart from regular assessments tomeasure memory decline, there is currently no accurate way ofpredicting who will or won't develop dementia.
For this study, published in the journal Alzheimer's &Dementia, Lovestone's team used blood samples from 1,148 people- 476 with Alzheimer's, 220 with mild cognitive impairment and452 elderly controls without dementia. They were analysed for 26proteins previously found to be linked with Alzheimer's.
The team found 16 of these 26 proteins to be stronglyassociated with brain shrinkage in either MCI or Alzheimer's andthen ran a second series of tests to see which of these couldpredict which patients would progress from MCI to Alzheimer's.
With this second series, they found a combination of 10proteins capable of predicting with 87 percent accuracy whetherpeople with MCI would develop Alzheimer's disease within a year.
Experts in the field welcomed the results but said theyshould be replicated in larger studies before an Alzheimer'sblood test could be rolled out for use in doctors' clinics.
"The results reported today are interesting, but as theauthors point out there is still a very large amount of workremaining until a usable blood test for Alzheimer's diseasebecomes available," said Adrian Pini of the MRC Centre forDevelopmental Neurobiology at King's College London.
James Pickett, head of research at the Alzheimer's Society,said the research "does not mean that a blood test for dementiais just around the corner".
"These 10 proteins can predict conversion to dementia withless than 90 percent accuracy, meaning one in 10 people wouldget an incorrect result," he said. "Accuracy would need to beimproved before it could be a useful diagnostic test." (Additional reporting by Ben Hirschler; Editing by Tom Heneghanand Jason Neely)
