Scientists may have identified a blood protein that could effectively predict a patient's risk of developing Mild Cognitive Impairment (MCI), which is linked to dementia and Alzheimer's disease, years before the earliest symptoms appear.

Researchers looked at data from more than100 sets of identical twins and found a single blood protein was associated with a 10-year decline in cognitive ability independent of age or genetics, King's College London reported.

"We're very optimistic that our research has the potential to benefit the lives of those who don't currently have symptoms of Alzheimer's, but are at risk of developing the disease," said co-author Claire Stevens.

The largest-of-its-kind study looked at more than 1,000 proteins in the blood of more than 200 healthy people using the lab test SOMAscan, which measures a vast amount of protein biomarkers simultaneously. They also assessed the patients' cognitive ability and compared the results with the blood sample analyses. For the first time, the researchers revealed blood levels of a protein called MAPKAPK5 tended to be lower in individuals whose cognitive ability started to decline within a period of 10 years.

"Although we are still searching for an effective treatment for Alzheimer's disease, what we do know is that prevention of the disease is likely to be more effective than trying to reverse it," said Steven Kiddle, lead author and Biostatistics Research Fellow at the MRC Social, Genetic & Developmental Psychiatry Centre at King's College London. "The next step will be to confirm whether or not our initial finding is specific for Alzheimer's disease, as this could lead to the development of a reliable blood test which would help clinicians identify suitable people for prevention trials."

The findings were published in a recent edition of the journal Translational Psychiatry.