An article summarizing the "investigations addressing the field of the early neurochemical differential diagnosis of Parkinson syndromes and the early diagnosis of Parkinson dementia" and providing an overview of the tested biomarkers was published over the summer 2090 by German researchers.

The authors conclude that "the specific biomarker for a certain neurological disease is yet to be identified—or better, several biomarkers. We think that a combination of multiple or at least two proteins will be necessary to differentiate [parkinsonian syndromes] as well as dementing syndromes from each other, as demonstrated for AD (tau/Aß) and CJD (tau, protein S-100B, and protein 14–3-3). Furthermore, we assume that the diagnostic question has to be very precise (e.g., PD or PDD, MSA versus PD)."

This full article is available online for free. See:
http://www.ncbi.nlm.nih.gov/pmc/article ... ool=pubmed --> HTML version
http://www.ncbi.nlm.nih.gov/pmc/article ... 5-0157.pdf --> PDF version

This table, in particular, lists all of the possible biomarkers for PD, PDD, DLB, PSP, and MSA:
http://www.ncbi.nlm.nih.gov/pmc/article ... ble/tbl17/

For me, the most interesting section of the article was about metals and whether they increase the risk for these diseases. (See "Metals: Believed to Be (Co)Factors of Aggregation") I understood very little of that section of the article but others of you will have a better chance.

Another interesting section was about the use of heart fatty acid-binding protein to differentiate PD from DLB and PD from PDD.

It was very interesting! A biomarker would certainly be helpful and it's nice to see some are being found. Regarding the metals, I couldn't help but wonder if deposition of metals could be a function of the disease process rather than a cause. In other words, maybe everyone is exposed to these metals but only those with certain pathologies store them in the brain, just as some store excessive amounts of iron in their tissue, as in hemochromatosis. --Pat

Because the diagnostic accuracy for DLB is so low, we really need biomarkers so that when clinical trials are conducted we have a pretty good idea that we only have DLBers enrolled (or DLB/ADers).

About the metals, it's always been fascinating to read neuropathology reports where metal deposits are described, if present. Surprisingly, not many reports mention these metal deposits in the brain.