Description
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.
Parkinsons 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.
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