RT Journal Article
SR Electronic
T1 Comorbid cortical β-amyloid plaques affect postural instability and gait disorder symptoms in Parkinson disease
JF Journal of Nuclear Medicine
JO J Nucl Med
FD Society of Nuclear Medicine
SP 469
OP 469
VO 53
IS supplement 1
A1 Muller, Martijn
A1 Albin, Roger
A1 Koeppe, Robert
A1 Frey, Kirk
A1 Bohnen, Nicolaas
YR 2012
UL http://jnm.snmjournals.org/content/53/supplement_1/469.abstract
AB 469 Objectives Postural instability and gait disorder (PIGD) symptoms are one of the hallmark symptoms of Parkinson disease (PD). Although impairments in PD have been attributed to nigrostriatal denervation, PIGD symptoms are less responsive to dopaminergic medications. As PIGD is a risk factor for future development of dementia in PD we examined the effects of cortical Aβ depositions ([11C]-PiB) and the degree of striatal dopaminergic denervation ([11C]-DTBZ) on PIGD in PD. Methods 40 PD patients (8F/32M; 69.7±6.1 (60-84) years; 7.2±4.9 (1-20) years motor disease duration; mean Hoehn and Yahr stage 2.7±0.5 (1.5-4) underwent [11C]-DTBZ and [11C]-PiB PET imaging, MDS-UPDRS, and computerized gait and balance assessments. The PIGD score was calculated as the mean of items 2.11-2.13 and 3.9-3.13 of the MDS-UPDRS. Standard spatiotemporal parameters were calculated for the computerized gait and balance assessments. Distribution Volume Ratio (DVR) was calculated for both [11C]-DTBZ and [11C]-PiB using the Logan plot approach. Results Increased PIGD score was associated with increased cortical [11C]-PiB DVR (ρ=0.374, p=0.018), but not with striatal [11C]-DTBZ DVR (ρ=-0.247, ns). Increased cortical [11C]-PiB DVR was also associated with increased sway in balance conditions in which vision was occluded (ρ=0.384, p=0.019) or erroneous (ρ=0.342, p=0.041). Increased cortical [11C]-PiB DVR was associated with decreased cadence (steps per minute; ρ=-0.391, p=0.018). Exclusion of ‘PiB positive’ patients (cortical [11C]-PiB DVR > 1.3, N=5) yielded similar significant results. Conclusions Balance and gait is negatively affected by comorbid cortical amyloid plaques in PD. The absence of a striatal dopaminergic effect on PIGD score and biomechanical parameters of balance and gait likely reflects severe striatal dopaminergic denervation, resulting in a statistical ‘floor’ effect. Prevention of comorbid cortical amyloid plaques may slow the progression of PIGD symptoms in PD in the course of the disease. Research Support NIH P01 NS015655 & RO1 NS070856 and Department of Veterans Affair