Do ten proteins hold the key to Alzheimer’s prognosis?

Written by Alice O’Hare, Future Science Group

In a collaboration led by King’s College London (London, UK) and Proteome Sciences (Surrey, UK), a group of scientists have investigated potential biomarkers to predict the progression of Alzheimer’s disease.

The team analysed data from three international studies, looking at blood samples from a total of 1148 individuals, and correlated plasma proteins with standard clinical assessments and neuroimaging techniques for Alzheimer’s diagnosis.

Early diagnosis of Alzheimer’s is important not only in clinical practice, but also in clinical trial enrolment, in order to develop effective treatment for this condition. The fact that there are currently no effective treatment options is often attributed to the fact that patients are recruited to such trials too late in disease progression, and therefore the drug fails to show therapeutic effect.

Approximately 10% of patients with mild cognitive impairment (MCI) develop Alzheimer’s disease within a year, however currently there are no accurate diagnostic tests to predict this decline (other than observation of memory decline). Previous studies have indicated the use of brain imaging or analysis of cerebrospinal fluid; however these are expensive and invasive options. A simple blood test would therefore be a useful addition to the physician’s toolbox.

In this multi-centre plasma validation study, 1148 elderly patients were studied – split between three groups; patients with diagnosed Alzheimer’s, patients with mild cognitive impairment and control patients without dementia.

The team started with 26 proteins that had already been linked to Alzheimer’s, and used multiplex assays  to analyse the samples for these, in addition to carrying out an MRI scan in approximately half of the patients (across the sample groups).

The team elucidated 16 proteins linked to brain shrinkage observed in Alzheimer’s and MCI patients. They then investigated whether any of these proteins could predict progression from MCI to Alzheimer’s. The team discovered ten proteins that could predict – with 87% accuracy, 85% sensitivity, and 88% specificity – the development of Alzheimer’s within a year.

Looking to future work, the authors explained: “To validate the clinical utility of the current study results, an independent study is required of an equal or greater size to test the accuracy of this panel of biomarkers.”

They are, however, hopeful that their findings will, ultimately, have wide implications in this field: “Such a marker set may have considerable value in triaging patients with early memory disorders, to other more invasive approaches such as molecular markers in CSF and PET imaging, in clinical trials and possibly in clinical practice.”

Source: Hye A, Riddoch-Contrerasa J, Baird AL et al. Plasma proteins predict conversion to dementia from prodromal disease. Alzheimers Dement. DOI: 10.1016/j.jalz.2014.05.1749 (2014) (Epub ahead of print).