Association between striatal amyloid deposition and motor prognosis in Parkinson's disease

Abstract

Background and purpose: The co-occurrence of amyloid-β pathology in Parkinson's disease (PD) is common; however, the role of amyloid-β deposition in motor prognosis remains elusive. This study aimed to investigate the association between striatal amyloid deposition, motor complications and motor prognosis in patients with PD.

Methods: Ninety-six patients with PD who underwent ¹⁸F florbetaben (FBB) positron emission tomography were retrospectively assessed. The ratio of the striatum to global (STG) FBB uptake was obtained for each individual, and patients were allotted into low and high STG groups according to the median value. The effect of STG group on regional amyloid deposition, the occurrence of motor complications and longitudinal change in levodopa equivalent dose (LED) requirement were investigated after controlling for age, sex, LED and disease duration at FBB scan.

Results: The high STG group was associated with lower cortical FBB uptake in the parietal, occipital and posterior cingulate cortices and higher striatal FBB uptake compared to the low STG group. Patients in the high STG group had a higher risk of developing wearing off and levodopa-induced dyskinesia than those in the low STG group, whereas the risk for freezing of gait was comparable between the two groups. The high STG group showed a more rapid increase in LED requirements over time than the low STG group.

Conclusions: These findings suggest that relatively high striatal amyloid deposition is associated with poor motor outcomes in patients with PD.

Keywords: Parkinson disease; amyloid‐β; motor complication; motor prognosis; striatum.

FIGURE 1

Box‐and‐whisker plots of regional SUVR according to STG group. Patients in the high STG group showed lower regional SUVR in the parietal, occipital and posterior cingulate cortices and higher regional SUVR in the striatum. ACC, anterior cingulate cortex; PCC, posterior cingulate cortex; STG, striatum to global ratio; SUVR, standardized uptake value ratio.

FIGURE 2

Kaplan–Meier survival curve of developing WO, LID and FoG. Curves of Kaplan–Meier estimates of developing WO, LID and FoG after symptom onset in the high STG group (in green) and low STG group (in red). Patients in the high STG group showed a higher risk of WO and LID during the follow‐up period. The risk of developing FoG was comparable between the two groups. FoG, freezing of gait; LID, levodopa‐induced dyskinesia; PD, Parkinson's disease; STG, striatum to global ratio; WO, wearing off.

FIGURE 3

Association between STG group and levodopa equivalent dose (LED) over time. A linear mixed model analysis showed a significant difference between the high STG (in green) and low STG (in red) groups (STG group × time interaction, p < 0.001). STG, striatum to global ratio.