Amyloid imaging of Lewy body-associated disorders

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Amyloid imaging of Lewy body-associated disorders

4 OCT 2010

Abstract

Clinicopathologic studies of Parkinson disease dementia (PDD) and dementia with

Lewy bodies (DLB) commonly reveal abnormal â-amyloid deposition in addition to

diffuse Lewy bodies (á-synuclein aggregates), but the relationship among these

neuropathologic features and the development of dementia in these disorders

remains uncertain. The purpose of this study was to determine whether amyloid-â

deposition detected by PET imaging with Pittsburgh Compound B (PIB)

distinguishes clinical subtypes of Lewy body-associated disorders. Nine healthy

controls, 8 PD with no cognitive impairment, 9 PD with mild cognitive

impairment, 6 DLB, and 15 PDD patients underwent [11C]-PIB positron emission

tomography imaging, clinical examination, and cognitive testing. The binding

potential (BP) of PIB for predefined regions and the mean cortical BP (MCBP)

were calculated for each participant. Annual longitudinal follow-up and

postmortem examinations were performed on a subset of participants. Regional PIB

BPs and the proportion of individuals with abnormally elevated MCBP were not

significantly different across participant groups. Elevated PIB binding was

associated with worse global cognitive impairment in participants with Lewy body

disorders but was not associated with any other clinical or neuropsychological

features, including earlier onset or faster rate of progression of cognitive

impairment. These results suggest that the presence of fibrillar amyloid-â does

not distinguish between clinical subtypes of Lewy body-associated disorders,

although larger numbers are needed to more definitively rule out this

association. Amyloid-â may modify the severity of global cognitive impairment in

individuals with Lewy body-associated dementia. © 2010 Movement Disorder Society

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