Preserved Serotonin Transporter Availability in Parkinson Disease Measured with Either [<sup>11</sup>C]MADAM or [<sup>11</sup>C]DASB: A Study Including 2 Separate Cohorts of Nondepressed Patients
Bibliographic record
Abstract
Serotonin transporter (SERT) availability was assessed using 2 tracers, [11C]N,N-dimethyl-2-(2-amino-4-cyanophenylthio)benzylamine ([11C]DASB) and [11C]N,N-dimethyl-2-(2-amino-4-fluoromethylphenylthio)benzylamine) ([11C]MADAM), in independent cohorts of patients and controls. This study aimed to independently confirm whether SERT remains intact in nondepressed individuals with early-stage Parkinson disease (PD), because the use of diverse methodologies could potentially yield disparate results. Methods: Seventeen PD patients (5 women and 12 men; age, 64 ± 7 y; Unified Parkinson’s Disease Rating Scale motor score, 23 ± 5; Beck Depression Inventory score, 5 ± 4) and 20 age- and sex-matched healthy controls underwent [11C]MADAM PET at Karolinska Institutet. Fifteen PD patients (5 women and 10 men; age, 59 ± 9 y; Unified Parkinson’s Disease Rating Scale motor score, 15 ± 7; Beck Depression Inventory score, 4 ± 4) and 8 controls were examined with [11C]DASB PET at the University of British Columbia. PET scans were performed at both institutions using a high-resolution research tomograph. A simplified reference tissue model and Logan graphical analysis were used to calculate the regional nondisplaceable binding potential (BPND), using the cerebellum as the reference. Parametric BPND images were generated using wavelet-aided parametric imaging. MRI-defined volumes of interest included cortical and subcortical regions, as well as brain stem nuclei. Results: There were no significant differences between controls and early-stage PD patients in either the [11C]DASB or the [11C]MADAM cohort, regardless of the analysis method. Group differences (Cohen d) in the [11C]DASB cohort ranged from 0.34 to 0.86 in brain stem nuclei, 0.09 to 0.61 in subcortical regions, and 0.28 to 0.70 in cortical regions. In the [11C]MADAM cohort, they ranged from 0.16 to 0.40, 0.19 to 0.55, and 0.32 to 0.61, respectively. Logan BPND highly correlated with simplified reference tissue model BPND for both tracers in each group (P < 0.001). Conclusion: SERT availability is relatively preserved in nondepressed patients with PD. This study suggests that serotonergic degeneration is not a major feature of the disease in nondepressed patients with nonadvanced disease.
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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 | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 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".