This report presents a comprehensive update on PD biomarker developments up to 2010. It covers the major classes of emerging and new markers relating to PD (blood, CSF, metabolomic, image-based, genetic and others), and focuses on those investigated in controlled human studies. This includes single and combined markers.
Parkinson's disease (PD) is the second most-common neurodegenerative disorder (after Alzheimer’s disease), and affects movement control. This condition develops due to the loss of dopamine-producing nerve cells in the Substantia Nigra, located in the mid brain. According to the US National Parkinson Foundation (NPF), 50 to 60,000 new cases of PD are diagnosed every year in the US, and one million people in the US already have the disease. Individual country incidence rates vary, but the NPF estimates that four to six million people around the world suffer from this condition.
In most cases, PD is diagnosed clinically. While this successfully identifies >90% of individuals requiring treatment for this condition, findings show that the first motor symptoms, such as bradykinesia, rigidity and tremor, may not occur until 30 to 50% of dopaminergic neurones have already been lost. This scenario creates an urgent need for tests that enable PD to be detected in its earliest stages, to allow appropriate treatment to begin.
Important advances have been made in the diagnosis of PD using imaging methods such as fluorodopa-PET and dopamine transporter SPECT. However, while these methods are important in clinical research, they are complex, expensive, not widely available and inappropriate for the routine screening of large populations. Likewise, genetic testing is important to PD in establishing traits, predisposition and risk but these tests do not or may not confirm the manifest presence of the disease.
These limitations create an urgent need for objective tests that detect and diagnose PD in its earliest stages, to allow appropriate treatments to begin. Such tests, if they are to meet patient requirements, should be simple, inexpensive, able to be used close to the clinical setting and available to all. Today, biomarkers are at the centre of efforts to develop these test capabilities.
This report presents a comprehensive update on PD biomarker developments up to April 2010. It covers the major classes of emerging and new markers relating to PD (blood, CSF, metabolomic, image-based, genetic and others), and focuses on those identified or investigated in controlled human studies. This includes single and combined markers.
This in-depth analysis of developments to date identified more than 45 PD biomarkers that are differentially expressed in PD, relative to controls. Of these, more than 40% are found in the blood or CSF. Combinations or multi-analyte profiles were considered as “single markers” for the purpose of this analysis. While efforts to identify markers to help understand or diagnose PD are at an early stage, important advances have been made in the last three years and show considerable promise. A number of companies and specialist groups (identified in this report) are working on the development of new marker-based diagnostic tests for PD. Recent advances in the identification of biomarkers in this field offer diagnostic opportunities and point the way to new therapeutic strategies.