Authors: Liu Shi (Department of Psychiatry, University of Oxford, UK)
Biomarker discovery for neurological diseases is burgeoning due to the advances in technologies that permit molecular measures taken from the brain, cerebrospinal fluid (CSF), plasma, saliva, urine and so on. Biomarkers could be biochemical changes (proteins, metabolomics and lipids), genetic alteration or changes in structural or functional features. They could help the diagnosis and detect the progression of these diseases, referred to as diagnostic and prognostic markers, respectively. Furthermore, biomarkers could help to measure the efficacy of the treatments, known as predictive markers.
The importance of biomarkers in neurological diseases should not be underestimated, particularly considering the large social and economic burden presently attributed to these diseases. This article describes the current status of blood-based biomarker research in neurological disorders, particularly in Alzheimer’s disease (AD), as well as addresses the main challenges and future direction of this field.
Current status of blood biomarker development in neurological disease
CSF is one of the main resources for biomarker development for neurological diseases given that CSF surrounds the brain and spinal cord. For example, the levels of amyloid and tau in CSF have been used in diagnosing AD . However, these measures are challenging because of invasiveness, cost and limited availability [2,3]. In part due to these limitations, increasing numbers of studies have attempted to find biomarkers in blood; a tissue that is easily accessible and suitable for repeated measures throughout the disease course or over the time-frame of an interventional study. Previous reviews have summarized much of this growing research effort to find biomarkers for AD diagnosis [4–11], as well as for other neurological disease [12–16]. Though it looks promising, it is important to note that there is no blood-based biomarker used in clinic for neurological disease diagnosis yet, mainly due to the lack of replication.