Presynaptic Striatal Dopaminergic Function in Atypical Parkinsonism: A Metaanalysis of Imaging Studies
Bibliographic record
Abstract
The purpose of this study was to determine whether striatal positron emission tomography (PET) and single-photon emission computed tomography (SPECT) imaging could be used to differentiate the atypical parkinsonian disorders multiple-system atrophy (MSA), progressive supranuclear palsy (PSP) and corticobasal syndrome (CBS) from the typical Parkinson disease (PD) for clinical and differential diagnostic purposes. Presynaptic tracers for dopamine transporter (DAT), aromatic amino acid decarboxylase (AADC) and vesicular monoamine type 2 (VMAT2) were investigated. \nA metaanalysis of 35 published presynaptic dopaminergic brain imaging studies of parkinsonian disorder patients and healthy controls was performed. PubMed was screened for eligible studies, and studies that fulfilled inclusion criteria determined by the study group were identified and included. Available striatal tracer binding values, disease severity scores as well as data concerning imaging methodology were extracted manually from the included studies. Collected data was synthesized using Meta-Essentials, with a statistical significance cut-off at 2-tailed P<0.05. Hedges g was used to estimate effect size in group comparisons. The data was screened for heterogeneity, and quality evaluation was performed using the Ottawa-Newcastle Scale. \nKey results from the synthesis showed a statistically significant difference in striatal DAT binding between PSP and PD, while PD and MSA-C or CBS did not demonstrate a significant difference. Caudal, but not putaminal DAT binding was significantly different between PD and MSA with predominant parkinsonism (MSA-P). A further significant DAT binding difference of 31.4% was found between the atypical parkinsonian syndromes PSP and MSA with predominant cerebellar ataxia (MSA-C). Clinical MSA subtypes MSA-C and MSA-P showed a 40.6% difference in DAT binding. The meta-analysis demonstrated a lower presynaptic dopaminergic function in PSP compared to both PD and MSA-P as measured by DAT binding, which may be diagnostically significant. The study provides evidence for the loss of caudate-to-putamen dopaminergic deficit gradient in MSA compared to PD.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.019 | 0.027 |
| Meta-epidemiology (narrow) | 0.003 | 0.001 |
| Meta-epidemiology (broad) | 0.013 | 0.039 |
| Bibliometrics | 0.005 | 0.008 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.004 | 0.002 |
| Open science | 0.002 | 0.002 |
| Research integrity | 0.002 | 0.002 |
| Insufficient payload (model declined to judge) | 0.002 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".