A protein in spinal fluid could be used to predict the risk of developing
Alzheimer's disease, according to German researchers.
Patients with high levels of the chemical - soluble amyloid precursor protein
beta - were more likely to develop the disease, they found.
Doctors said in the journal Neurology this was more precise than other tests.
Alzheimer's Research UK said early diagnosis was a key goal, and the study
represented a potential new lead.
Doctors analysed samples of spinal fluid from 58 patients with mild cognitive
impairment, a memory-loss condition which can lead to Alzheimer's.
The patients were followed for three years. Around a third developed
Alzheimer's.
Those who developed the illness had, on average, 1,200 nanograms/ml of the
protein in the spinal fluid at the start of the study.
Those who did not started with just 932 nanograms/ml.
Beta amyloid proteins have already been implicated in Alzheimer's itself, but
not as a "predictor" of the disease.
The researchers said that a combination of soluble amyloid precursor protein
beta, defective tau proteins, which are involved in the structure of brain
cells, and a patient's age was 80% accurate in predicting the onset of the
disease.
Early diagnosis crucial
There is no cure for Alzheimer's disease. If a treatment is developed, it is
thought that it would need to be delivered early, before any permanent damage
was done.
Dr Robert Perneczky, from the Technical University Munich, said: "Being able to
identify who will develop Alzheimer's disease very early in the process will be
crucial in the future.
"Once we have treatments that could prevent Alzheimer's disease, we could begin
to treat very early and hopefully prevent the loss of memory and thinking
skills that occurs with this devastating disease."
More than 800,000 people have dementia in the UK, and that figure is expected
to rise as populations get older.
Rebecca Wood, chief executive of Alzheimer's Research UK, said: "The ability to
diagnose Alzheimer's early is a key goal for doctors and researchers. This
small study provides a potential new lead to follow up.
"We will need to see larger trials before we can know how accurate this method
could be as a diagnostic test. It will also be important to see how
measurements of these proteins compare to those found in healthy people."