Common Ground: Is Aâ the Foundation for Multiple Dementias?

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Common Ground: Is Aâ the Foundation for Multiple Dementias?

27 August 2010

The majority of patients with Parkinson disease eventually develop dementia, but

what pathology underlies this decline? In PD, as well as in dementia with Lewy

bodies (DLB), intracellular aggregates composed primarily of á-synuclein gum up

the specific dopaminergic neurons, but PD patients live with these Lewy bodies

for many years before they experience cognitive losses. Intriguingly, scientists

have found evidence of amyloid-â (Aâ) pathology in both Parkinson disease

dementia (PDD) and DLB, suggesting a role for Aâ in these diseases. Now, two new

papers firm up that idea. In the August 18 Neurology online, researchers led by

Siderowf at the University of Pennsylvania, Philadelphia, report on the

first longitudinal study to examine changes in the Alzheimer's marker Aâ42 in

the cerebrospinal fluid (CSF) of PD patients. They found that low levels of Aâ42

predicted significant cognitive decline within the next two years, hinting that

Aâ pathology is involved in Parkinson's dementia. Meanwhile, in the August 23

Lancet, scientists led by Murat Emre at Istanbul University, Turkey, describe

the largest trial to date studying the efficacy of the N-methyl D-aspartate

(NMDA) receptor antagonist memantine, which is approved for treatment of AD, in

patients with PDD and DLB. Emre and colleagues found that memantine provides a

moderate benefit to DLB patients. Together, these studies raise intriguing

questions about the interrelatedness of these disorders, with implications for

research, diagnosis, and treatment.

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http://www.alzforum.org/new/detail.asp?id=2544