Objective: To investigate differences in striatal presynaptic dopamine function between multiple system atrophy (MSA) and progressive supranuclear palsy (PSP) using combined data from all available PET and SPECT studies.

Background: Presynaptic striatal dopaminergic functional brain imaging detects dopaminergic defects in Parkinson’s disease (PD) and atypical parkinsonisms. However, possible differences in presynaptic striatal dopamine function between PD, MSA and PSP are unclear. In contrast to PD (Kaasinen & Vahlberg 2017), there are no previous meta-analyses of dopaminergic brain imaging data in atypical parkinsonisms.

Methods: The PRISMA statement was followed. For this quantitative meta-analysis, studies were collected from PubMed using a systematic search on March 7, 2018. Full-text articles were obtained and assessed if they were deemed relevant to the analysis or if their eligibility could not be determined from title and abstract alone. PET and SPECT imaging investigating L-amino acid decarboxylase (AADC) activity, dopamine transporter (DAT) binding and vesicular monoamine transporter 2 (VMAT2) were included in this study. Heterogeneity of the data were examined using I2 statistics and a random effect model was used to summarize data. Hedges g was used as an estimator of effect size in group comparisons. The level of significance was set at p<0.05.

Results: Altogether 32 studies (26 DAT, 6 AADC, no VMAT2 studies) with 327 MSA patients and 204 PSP patients were included in the analysis. PSP patients had lower caudate nucleus (12 studies, Hedges g = -1.17, 95% CI = -1.61 to -0.72, p<0.001) and putamen (-0.70, -1.15 to -0.26, p<0.001) DAT binding compared to PD patients. There were no differences in striatal DAT binding between MSA and PD patients (13 studies, Hedges g caudate = -0.27, putamen=-0.14, p>0.11). Caudate nucleus DAT binding was lower in PSP as compared to MSA (7 studies, Hedges g = -0.51, 95% CI = -1.04 to -0.02, p=0.02) but there were no differences in the putamen between MSA and PSP (Hedges g = -0.33, p=0.12).

Conclusions: Combined data from brain imaging studies suggest that striatal DAT binding is decreased in PSP as compared to PD, whereas there are no differences between MSA and PD. PSP patients also appear to have lower caudate nucleus DAT binding as compared to patients with MSA.

References: Kaasinen V, Vahlberg T. Striatal dopamine in Parkinson’s disease: a meta-analysis of imaging studies. Ann Neurol 2017; 82: 873-882

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MDS Abstracts - https://www.mdsabstracts.org/abstract/striatal-dopamine-function-in-multiple-system-atrophy-and-progressive-supranuclear-palsy-a-meta-analysis-of-imaging-studies/