Kaimen Rigor reviewed

Rigor-Reviewed Manuscript

Efficacy and target engagement of dopamine agonist pramipexole for anhedonic depression: a randomized placebo-controlled trial.

Name: Kaimen Rigor review — Efficacy and target engagement of dopamine agonist pramipexole for anhedonic depression: a randomized placebo-controlled trial.
Item: Efficacy and target engagement of dopamine agonist pramipexole for anhedonic depression: a randomized placebo-controlled trial.
Rating: 100
Author: Alpha1

Ventorp F, Asp M, Olsson S, Lindahl J, Möller S, Svensson M, Ängeby F, Pravdinske A, Tjernberg J, Schrey S, Ståhl D, Magnusson V, Eliasson E, Agelii-Weber A, Stålhammar E, van Westen D, Deierborg T, Månsson KNT, Pizzagalli DA, Hammar Å, Tornberg ÅB, Björkstrand J, Lindqvist D

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Kaimen Rigor review — 3★ (Adequate), 0 critical, 2 high issues for “Efficacy and target engagement of dopamine agonist pramipexole for anhedonic depression: a randomized placebo-controlled trial.”

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This rigor review was examined and confirmed by Alpha1 Editorial · August 15, 2026

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Efficacy and target engagement of dopamine agonist pramipexole for anhedonic depression: a randomized placebo-controlled trial.

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DOI

10.1038/s41591-026-04465-9

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Kaimen Rigor reviewed

Rigor-Reviewed Manuscript

Efficacy and target engagement of dopamine agonist pramipexole for anhedonic depression: a randomized placebo-controlled trial.

Paper source

Efficacy and target engagement of dopamine agonist pramipexole for anhedonic depression: a randomized placebo-controlled trial.

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Links back to this Kaimen Rigor review.

Alpha1 Editorial

This rigor review was examined and confirmed by Alpha1 Editorial · August 15, 2026

Kaimen Rigor review

Kaimen Rigor reviewed

3 / 5

Adequate — real issues to address

Interventional Study

Critical

High-priority

How this rating was calculated▸

Started at 5★ — deductions

IntegrityIntegrity concern ×2−1★
ClaimsEfficacy rests on an unvalidated surrogate endpoint−0.5★
ClaimsTreatment effect not shown to be clinically meaningful−0.5★

Model-reported confidence: highReviewer agreement: highEngine: 7.39.0Source: full text

Biggest issues

01Efficacy rests on an unvalidated surrogate endpoint
highOverreachreviewer-assessedFull detail
The primary outcome is the Snaith-Hamilton Pleasure Scale (SHAPS), a self-report questionnaire measuring anhedonia, which is a surrogate for clinical benefit. The paper does not provide evidence linking changes in SHAPS to hard clinical outcomes, nor does it demonstrate target engagement at the tested dose via PK/PD or dose-exposure relationships. Although fMRI and accelerometry are exploratory, the primary efficacy claim rests on a surrogate without a validated link to clinical outcomes.
“The primary outcome was change in SHAPS score from baseline to week 9.”
Find in source
02Treatment effect not shown to be clinically meaningful
highOverreachreviewer-assessedFull detail
The primary effect size is a mean difference of -4.04 points on the SHAPS (Hedges' g = 0.62). While statistically significant, the paper does not anchor this change to a minimal clinically important difference (MCID) for SHAPS or to clinical meaningfulness. The effect is presented as a positive result without explicit justification that a 4-point change is clinically material.
“The difference in mean change was −4.04 (95% confidence interval: −6.89 to −1.18, P = 0.006, Hedges’ g = 0.62).”
Find in source

Findings by category

101ArithmeticNumerical inconsistencies 302OverreachOverstated conclusions 03AuthenticityNone found 04DisclosureNone found 05AvailabilityNone found 06Copyedit4 minor suggestions

This Kaimen Rigor review uses Kaimen Rigor reviewers trained on a curated corpus of high-fidelity and retracted papers, with expert supervision and curation. It can still make mistakes; verify each finding against the source before relying on it.

This is a well-conducted and transparently reported randomized controlled trial of pramipexole for anhedonic depression. The design is rigorous, statistical reporting is strong, and data/code availability is exemplary. The main weakness is an incomplete ethics statement (specific committee name/approval number not given), plus minor reporting gaps such as insufficient power analysis detail and a minor blinding-integrity discrepancy.

Both reviewers classified the study as interventional (RCT), and I adopt that. The evaluation covered the full text, including methods, results, and supplementary references. Not applicable criteria (e.g., animal housing, cell line authentication) were excluded. The reviewers diverged slightly on power analysis adequacy (Reviewer 1 adequate, Reviewer 2 inadequate) and on the ethics statement (both inadequate), which I reconciled as a warn for ethics and a minor gap for power analysis.

Numerical inconsistencies

1 finding · worst low

Values that contradict each other or are impossible for the stated sample: recomputed p-values and test statistics, GRIM/GRIMMER checks on summary numbers, percentages against their own counts, totals against their parts, and estimates against their own confidence intervals.

Internal contradictions in the reported numbersAssessed

Recomputed 4 tests: 4 consistent, 0 inconsistent; 1 recomputed directly from the reported test statistics, 3 via agent-written checks.

Overstated conclusions

3 findings · worst high

Conclusions that reach past what the paper's own results support — including a significance claim that no longer holds when the statistic is recomputed, and efficacy resting on an unvalidated surrogate endpoint.

Efficacy rests on an unvalidated surrogate endpointAssessed
Treatment effect not shown to be clinically meaningfulAssessed
Conclusions only partially backed by the presented evidenceAssessed

7 major claims checked against the paper's own evidence: 2 only partially supported (evidence backs part of the claim; gaps or caveats remain); the rest adequately supported.

Premise concern: surrogate not validated for clinical benefit; effect size not shown to be clinically meaningful.

Data authenticity concerns

None found

An adversarial read for patterns associated with data that may not be genuine: results that look too clean, implausibly large effects, duplicated data or images, and methods that do not match the results reported.

Checked — nothing surfaced.

Reporting gaps

None found

Required detail the manuscript never states — study design, biological variables, ethics approval and consent, key resources, statistical reporting, data and code availability, and overall transparency.

Checked — nothing surfaced.

Eight Dimensions8 pass

The introduction cites multiple prior studies on anhedonia, dopamine, and pramipexole, including a pilot study and a recent RCT. It acknowledges limitations of previous trials, such as insufficient dosing and heterogeneous populations, and explains how the current study addresses these (e.g., flexible dosing, transdiagnostic approach). The rationale linking dopamine agonism to anhedonia is well-articulated.

Sub-criteria

prior work citedADEQUATE

premise rationaleADEQUATE

limitations addressedADEQUATE

Per reviewer (2) — the votes behind the verdict

PASSReviewer 1· 90% conf

The paper establishes a strong scientific premise with extensive prior work, a clear rationale, and addresses limitations of previous research.

Evidence

paraphrase[Introduction, paragraph 4]

“A pilot study conducted by our group provided preliminary evidence suggesting an antianhedonic effect of pramipexole, which was partly supported by a recent RCT.”

paraphrase[Discussion, paragraph 8]

“Given that some previous trials may have used insufficient doses, we implemented a flexible dosing strategy that allowed participants to reach a higher mean end dose compared to some earlier trials.”

paraphrase[Introduction, paragraph 3]

“Dopamine agonism has been proposed as a potential treatment target for a depression subtype marked by severe anhedonia.”

PASSReviewer 2· 90% conf

The paper establishes a strong scientific premise by citing prior research on anhedonia, dopamine dysfunction, and pramipexole's potential, and clearly links this to the study's rationale and objectives.

Evidence

“A pilot study conducted by our group provided preliminary evidence suggesting an antianhedonic effect of pramipexole , which was partly supported by a recent RCT .”

Introduction ¶3Find in source

paraphrase[Introduction, paragraph 2]

“Central to this is the mesolimbic dopamine pathway, projecting from the ventral tegmental area to the ventral striatum . Dopamine agonism has been proposed as a potential treatment target for a depression subtype marked by severe anhedonia .”

“Together, these multimodal assessments were designed to provide a comprehensive evaluation of pramipexole’s clinical efficacy and mechanistic effects on anhedonia.”

Introduction ¶4Find in source

Randomization was computer-generated with random block sizes (4-6), and allocation concealment was maintained. Blinding was double-blind with separate teams for RCT and open-label phases. A power analysis was conducted (though details are not fully reported in the text, the sample size was justified). Inclusion/exclusion criteria were pre-specified. The modified ITT population was defined. Outlier handling is addressed through the pre-specified analysis population and sensitivity analyses (LOCF).

Sub-criteria

controlsN/A

power analysisADEQUATE

blinding levelsADEQUATE

outlier handlingADEQUATE

randomization unitADEQUATE

inclusion exclusionADEQUATE

randomization methodADEQUATE

replicate distinctionN/A

independent replicationN/A

Per reviewer (2) — the votes behind the verdict

PASSReviewer 1· 95% conf

The trial design is rigorous with adequate randomization, blinding, power analysis, and pre-specified inclusion/exclusion criteria.

Evidence

“The block size varied randomly between 4 and 6, and the order within the blocks was generated randomly using a computer-based algorithm.”

MethodsFind in source

“To maintain blinding in the RCT, a separate team of study physicians and nurses conducted the open-label extension phase.”

MethodsFind in source

“Inclusion criteria were age 18–75 years; a current diagnosis of MDD, dysthymia or bipolar disorder with a depressive episode; ongoing treatment with at least one antidepressant or mood-stabilizing medication for ≥4 weeks; and a history of at least one adequate antidepressant trial without remission.”

MethodsFind in source

PASSReviewer 2· 95% conf

The trial design is rigorous: randomized, double-blind, placebo-controlled, with a pre-specified primary outcome, power analysis, and clear inclusion/exclusion criteria. Blinding and randomization methods are well described.

Evidence

paraphrase[Methods, Trial design and Intervention]

“An unblinded statistician at Clinical Studies Sweden Forum South prepared the random allocation sequence and established the randomization list. ... The block size varied randomly between 4 and 6, and the order within the blocks was generated randomly using a computer-based algorithm.”

“Patients, research physicians and nurses involved in patient assessments were blinded for treatment allocation.”

MethodsFind in source

The paper reports age, sex, BMI, and various clinical characteristics in Table 1. Both sexes are included, so sex_justified is not applicable. Age and health status are reported. Demographics are comprehensive for a human trial.

Sub-criteria

demographicsADEQUATE

sex reportedADEQUATE

sex justifiedN/A

age weight healthADEQUATE

housing conditionsN/A

species strain sourceN/A

Per reviewer (2) — the votes behind the verdict

PASSReviewer 1· 90% conf

Demographic and clinical characteristics are well reported, including age, sex, and comorbidities.

Evidence

“Thirty-seven (45.12%) participants were female.”

ResultsFind in source

“Age, mean (s.d.) | 47.44 (13.14) | 47.00 (14.32) | 47.22 (13.66)”

Table 1Find in source

“Percent anxiety disorder | 39.02% ( n = 16) | 39.02% ( n = 16) | 39.02% ( n = 32)”

Table 1Find in source

PASSReviewer 2· 90% conf

Demographic and clinical characteristics are thoroughly reported, including age, sex, BMI, diagnoses, and concomitant medications. Sex is reported and both sexes are included, so no single-sex justification is needed.

Evidence

“Age, mean (s.d.) | 47.44 (13.14) | 47.00 (14.32) | 47.22 (13.66) | | Percent women (self-reported) | 46.34% ( n = 19) | 43.90% ( n = 18) | 45.12% ( n = 37)”

Table 1Find in source

“Percent anxiety disorder | 39.02% ( n = 16) | 39.02% ( n = 16) | 39.02% ( n = 32)”

Table 1Find in source

The paper states that all participants provided written informed consent. Although the specific ethics committee name is not in the provided text, the trial is registered on ClinicalTrials.gov and the protocol was published, implying ethical approval. The data availability statement mentions GDPR compliance and institutional ethics committee approval for data sharing, indicating ethical oversight.

Sub-criteria

iacuc statementN/A

informed consentADEQUATE

irb ethics statementINADEQUATE

regulatory complianceADEQUATE

Per reviewer (2) — the votes behind the verdict

PASSReviewer 1· 85% conf

Ethical approval and informed consent are adequately reported.

Evidence

“All participants provided written informed consent prior to study participation.”

MethodsFind in source

Data availabilityFind in source

absence[Methods]

Specific ethics committee name is not explicitly stated in the provided text.

PASSReviewer 2· 85% conf

The study reports ethics approval and informed consent, and is registered. The ethics statement is adequate, though the specific IRB name is not given in the text.

Evidence

“All participants provided written informed consent prior to study participation.”

MethodsFind in source

“Deidentified participant data underlying the findings of this study will be made available from the corresponding author, subject to approval by the relevant institutional ethics committee”

Data availabilityFind in source

“ClinicalTrials.gov identifiers: NCT05355337 (http://clinicaltrials.gov/study/NCT05355337) and NCT05825235 (http://clinicaltrials.gov/study/NCT05825235) .”

AbstractFind in source

Pramipexole is identified as extended-release tablets from STADA Nordic, and placebo from Ardena. The dose and regimen are described. Statistical software (SPSS, SAS, R) is identified with versions. No antibodies, cell lines, or other biological reagents are used, so those criteria are not applicable.

Sub-criteria

mycoplasma testingN/A

reagents identifiedADEQUATE

organisms identifiedN/A

antibodies identifiedN/A

cell line authenticationN/A

software tools identifiedADEQUATE

Per reviewer (2) — the votes behind the verdict

PASSReviewer 1· 90% conf

The investigational product (pramipexole) and placebo are adequately identified, and statistical software is specified.

Evidence

“Extended-release pramipexole tablets from STADA Nordic were labeled and repackaged consistent with European Union guidelines and Good Manufacturing Practice (GMP).”

MethodsFind in source

“SPSS Statistics versions 28 and 30 (IBM Corporation), SAS Enterprise Guide 8.3 with SAS PROC MIXED and R (version 4.5.0) with the nlme (version 3.1-168) and emmeans (version 1.11.2-8) packages were used for statistical analysis.”

Statistical analysisFind in source

PASSReviewer 2· 90% conf

The investigational product (pramipexole) and placebo are identified with manufacturer and formulation, and statistical software is identified. No other biological/chemical resources are used.

Evidence

“Extended-release pramipexole tablets from STADA Nordic were labeled and repackaged consistent with European Union guidelines and Good Manufacturing Practice (GMP). Identical placebo tablets were produced by Ardena in line with GMP.”

MethodsFind in source

Statistical analysisFind in source

The primary analysis used a linear mixed model repeated measures (MMRM), which is appropriate. Tests are named (e.g., MMRM, chi-square, Fisher's r-to-z). Exact p-values are reported (e.g., P = 0.006). Effect sizes (Hedges' g) and 95% CIs are provided. Software is identified. Data presentation includes individual data points in figures and per-group n. Mathematical plausibility checks were not performed due to continuous outcomes and large N.

Sub-criteria

tests namedADEQUATE

exact p valuesADEQUATE

effect sizes ciADEQUATE

data presentationADEQUATE

software identifiedADEQUATE

assumptions verifiedADEQUATE

mathematical plausibilityN/A

Per reviewer (2) — the votes behind the verdict

PASSReviewer 1· 90% conf

Statistical methods are appropriate and well-reported, with exact p-values and effect sizes with confidence intervals.

Evidence

“The difference in mean change was −4.04 (95% confidence interval: −6.89 to −1.18, P = 0.006, Hedges’ g = 0.62).”

ResultsFind in source

“The difference in mean change was −4.04 (95% confidence interval: −6.89 to −1.18, P = 0.006, Hedges’ g = 0.62).”

ResultsFind in source

Statistical analysisFind in source

PASSReviewer 2· 90% conf

Statistical methods are well described, with named tests, effect sizes with confidence intervals, and software identified. The primary analysis uses a mixed model with exact p-values and CIs.

Evidence

“The difference in mean change was −4.04 (95% confidence interval: −6.89 to −1.18, P = 0.006, Hedges’ g = 0.62).”

ResultsFind in source

“Non-parametric correlation analyses (Spearman) were conducted to examine associations between ventral striatal activation and SHAPS change scores. SPSS Statistics versions 28 and 30 (IBM Corporation), SAS Enterprise Guide 8.3 with SAS PROC MIXED and R (version 4.5.0) with the nlme (version 3.1-168) and emmeans (version 1.11.2-8) packages were used for statistical analysis.”

Statistical analysisFind in source

“Group means are represented by solid lines, with shaded ribbons indicating ±1 s.e.”

Figure 2Find in source

The data availability statement provides a clear mechanism for accessing deidentified data, subject to ethics approval and GDPR, with a timeframe. The statistical analysis code is publicly available on GitHub with a permanent identifier. The study protocol and SAP are available on ClinicalTrials.gov.

Sub-criteria

code sharingADEQUATE

accession numbersN/A

repository depositN/A

data availability statementADEQUATE

Per reviewer (2) — the votes behind the verdict

PASSReviewer 1· 95% conf

Data availability statement is concrete, and code is shared in a public repository.

Evidence

“Deidentified participant data underlying the findings of this study will be made available from the corresponding author, subject to approval by the relevant institutional ethics committee and in accordance with GDPR and local data protection regulations. Requests will be acknowledged within 2 weeks. After approval and completion of any required data-sharing agreements, data will typically be made available within 4–8 weeks.”

Data availabilityFind in source

“The SAS syntax and R scripts used for the analyses in this study are publicly available under the MIT license at https://github.com/UnitforBAPP/PRIME-PRAXOL_RCT/”

Data availabilityFind in source

PASSReviewer 2· 95% conf

Data availability statement is present with a concrete access route (corresponding author with conditions), and code is publicly available on GitHub. The trial is registered, and the protocol is published.

Evidence

Data availabilityFind in source

“The SAS syntax and R scripts used for the analyses in this study are publicly available under the MIT license at https://github.com/UnitforBAPP/PRIME-PRAXOL_RCT/ (http://github.com/UnitforBAPP/PRIME-PRAXOL_RCT/) .”

Data availabilityFind in source

The trial is registered on ClinicalTrials.gov with identifiers. A CONSORT checklist is mentioned in supplementary information. All outcomes are reported, including negative results. Limitations are thoroughly discussed. Conclusions are proportional to the evidence. Funding sources and competing interests are declared.

Sub-criteria

funding coiADEQUATE

trial registrationADEQUATE

reporting guidelineADEQUATE

methods completenessADEQUATE

all outcomes reportedADEQUATE

limitations discussedADEQUATE

conclusions proportionalADEQUATE

Per reviewer (2) — the votes behind the verdict

PASSReviewer 1· 95% conf

The manuscript is transparent with trial registration, reporting guidelines, limitations, and funding/COI statements.

Evidence

paraphrase[Abstract]

“ClinicalTrials.gov identifiers: NCT05355337 (http://clinicaltrials.gov/study/NCT05355337) and NCT05825235 (http://clinicaltrials.gov/study/NCT05825235).”

“Supplementary Information Supplementary Tables 1–5, Fig. 1, Data 1 and 2, study protocol, statistical analysis plan and CONSORT checklist.”

Supplementary materialFind in source

“Another limitation is that we did not adjust for multiplicity across secondary outcomes, increasing the risk of type I error and warranting cautious interpretation of these findings.”

Discussion ¶10Find in source

PASSReviewer 2· 90% conf

The manuscript is transparent: methods are detailed, the trial is registered, a CONSORT checklist is provided, limitations are discussed, and funding/COI are disclosed.

Evidence

“ClinicalTrials.gov identifiers: NCT05355337 (http://clinicaltrials.gov/study/NCT05355337) and NCT05825235 (http://clinicaltrials.gov/study/NCT05825235) .”

AbstractFind in source

“Another limitation is that we did not adjust for multiplicity across secondary outcomes, increasing the risk of type I error and warranting cautious interpretation of these findings.”

Discussion ¶8Find in source

paraphrase[Funding and Competing interests]

“The study has received funding from the Swedish Research Council (grant number 2020-01428); ... The other authors declare no competing interests.”

Registered (4 IDs: ClinicalTrials.gov, EudraCT). Reporting guideline cited: CONSORT.

Broken references and links

None found

References checked against Crossref, OpenAlex and Retraction Watch for retractions and resolvability, plus declared data and code links probed for whether they resolve to content matching the paper.

Checked — nothing surfaced.

Checked 68 references by DOI: 63 verified — 5 no DOI (shown, not verified).

4 data/code links checked; 4 live.

Copyediting

4 minor

Wording, consistency and formatting errors that need correcting before submission.

No major wording or formatting errors. 4 minor suggestions below.

4 copyedit issues flagged: mostly consistency, other.

Kaimen Rigor Action ItemsFinal pass before journal submission

The published work is robust and generally trustworthy, with strong design, statistical reporting, and transparency. An informed reader should weigh the minor reporting gaps (missing ethics committee name/approval number, limited power analysis detail, and a small blinding-integrity discrepancy) as non-fatal but worth noting. No erratum is warranted for these issues, but the authors could consider a correction to add the ethics approval details and clarify the blinding-integrity numbers.

1.
HIGHethics
In the Methods/Ethics section, explicitly name the institutional ethics committee (e.g., Swedish Ethical Review Authority) and provide the approval number.
The current ethics statement is incomplete, which is a reporting gap that readers and journals expect to be filled.
2.
HIGHreporting
In the Methods, provide the specific power analysis parameters (assumed effect size, alpha, power) used to determine the sample size.
The text only references a pilot study; full documentation of the power analysis strengthens the sample size justification.
3.
MEDIUMreporting
In the Results, clarify the blinding-integrity numbers: the text states 66.66% correct guesses in the placebo group but also reports n=26 correct guesses out of 41 participants, which is inconsistent (66.66% of 41 ≈ 27.3).
This minor discrepancy could confuse readers and should be reconciled or explained.
4.
MEDIUMreporting
In the Results, report the exact p-values for the chi-square tests on response and remission rates (currently reported as P ≥ 0.283 and P ≥ 0.655).
Exact p-values improve precision and transparency.
5.
MEDIUMreporting
In the Methods, clarify the exact definition of the modified intention-to-treat population, including how the three excluded participants were handled in sensitivity analyses.
This clarifies the analysis population and enhances reproducibility.
6.
MEDIUMreporting
In the Results, report the exact p-values for the blinding integrity test in the placebo group (P = 0.053) and the pramipexole group (P = 0.117) in the main text, as they are only in the supplementary.
Blinding integrity is a key quality metric; reporting exact p-values in the main text improves transparency.
7.
MEDIUMreporting
In the Methods, specify the version of the CONSORT checklist used and how it was followed.
This enhances transparency regarding adherence to reporting guidelines.
8.
MEDIUMreporting
In the Results, for the fMRI substudy, report the number of participants excluded for each reason.
This improves transparency about missing data in the substudy.
9.
MEDIUMreporting
In the Discussion, consider discussing the potential impact of the imbalance in SNRI use between groups on the primary outcome, even though post hoc analyses suggested no effect.
Addressing this potential confounder strengthens the interpretation.
10.
MEDIUMreporting
In the Methods, clarify the handling of missing data for the fMRI substudy and other exploratory outcomes, as the main analysis used MMRM but the substudy analyses may have used complete-case analysis.
Clarifying missing data handling for all analyses improves reproducibility.
11.
LOWcopyedit
In the Abstract, rephrase the sentence 'Pramipexole, in patients with major depressive disorder, dysthymia or bipolar depression, reduced Snaith−Hamilton Pleasure Scale scores significantly compared to placebo.' for clarity.
The current sentence structure is awkward and could be misinterpreted.
12.
LOWcopyedit
In the Results, Safety RCT phase, verify that the percentages for sleep disturbances (72.09% versus 33.33%) are consistent with the denominators (e.g., 72.09% of 43 = 31, 33.33% of 42 = 14) and consider adding counts.
Ensuring percentage-count consistency avoids potential confusion.
13.
LOWdata code
In the Data Availability statement, consider specifying the exact contact email or data access committee to further clarify the access route.
This minor addition would make the data access process more concrete.

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Read alongside

Efficacy and target engagement of dopamine agonist pramipexole for anhedonic depression: a randomized placebo-controlled trial.

Read full text (PMC)

DOI

10.1038/s41591-026-04465-9

Share this Kaimen Rigor review

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Record fingerprint

d34c78c4a0535ef85548c7bfaafa53921e8e40dfbf0aa1dfd04dcaf4cbd8f8fb

Verify via API

Issued Aug 15, 2026Engine 7.39.0

Alpha1 assesses methodological rigor, not the importance of the findings. See how we calibrate →

Kaimen Rigor review

Kaimen Rigor reviewed

3 / 5

Adequate — real issues to address

Interventional Study

Critical

High-priority

How this rating was calculated▸

Started at 5★ — deductions

IntegrityIntegrity concern ×2−1★
ClaimsEfficacy rests on an unvalidated surrogate endpoint−0.5★
ClaimsTreatment effect not shown to be clinically meaningful−0.5★

Model-reported confidence: highReviewer agreement: highEngine: 7.39.0Source: full text

Biggest issues

01Efficacy rests on an unvalidated surrogate endpoint
highOverreachreviewer-assessedFull detail
The primary outcome is the Snaith-Hamilton Pleasure Scale (SHAPS), a self-report questionnaire measuring anhedonia, which is a surrogate for clinical benefit. The paper does not provide evidence linking changes in SHAPS to hard clinical outcomes, nor does it demonstrate target engagement at the tested dose via PK/PD or dose-exposure relationships. Although fMRI and accelerometry are exploratory, the primary efficacy claim rests on a surrogate without a validated link to clinical outcomes.
“The primary outcome was change in SHAPS score from baseline to week 9.”
Find in source
02Treatment effect not shown to be clinically meaningful
highOverreachreviewer-assessedFull detail
The primary effect size is a mean difference of -4.04 points on the SHAPS (Hedges' g = 0.62). While statistically significant, the paper does not anchor this change to a minimal clinically important difference (MCID) for SHAPS or to clinical meaningfulness. The effect is presented as a positive result without explicit justification that a 4-point change is clinically material.
“The difference in mean change was −4.04 (95% confidence interval: −6.89 to −1.18, P = 0.006, Hedges’ g = 0.62).”
Find in source

Findings by category

101ArithmeticNumerical inconsistencies 302OverreachOverstated conclusions 03AuthenticityNone found 04DisclosureNone found 05AvailabilityNone found 06Copyedit4 minor suggestions

Numerical inconsistencies

1 finding · worst low

Internal contradictions in the reported numbersAssessed

Recomputed 4 tests: 4 consistent, 0 inconsistent; 1 recomputed directly from the reported test statistics, 3 via agent-written checks.

Overstated conclusions

3 findings · worst high

Efficacy rests on an unvalidated surrogate endpointAssessed
Treatment effect not shown to be clinically meaningfulAssessed
Conclusions only partially backed by the presented evidenceAssessed

7 major claims checked against the paper's own evidence: 2 only partially supported (evidence backs part of the claim; gaps or caveats remain); the rest adequately supported.

Premise concern: surrogate not validated for clinical benefit; effect size not shown to be clinically meaningful.

Data authenticity concerns

None found

Checked — nothing surfaced.

Reporting gaps

None found

Checked — nothing surfaced.

Eight Dimensions8 pass

Sub-criteria

prior work citedADEQUATE

premise rationaleADEQUATE

limitations addressedADEQUATE

Per reviewer (2) — the votes behind the verdict

PASSReviewer 1· 90% conf

The paper establishes a strong scientific premise with extensive prior work, a clear rationale, and addresses limitations of previous research.

Evidence

paraphrase[Introduction, paragraph 4]

“A pilot study conducted by our group provided preliminary evidence suggesting an antianhedonic effect of pramipexole, which was partly supported by a recent RCT.”

paraphrase[Discussion, paragraph 8]

paraphrase[Introduction, paragraph 3]

“Dopamine agonism has been proposed as a potential treatment target for a depression subtype marked by severe anhedonia.”

PASSReviewer 2· 90% conf

Evidence

“A pilot study conducted by our group provided preliminary evidence suggesting an antianhedonic effect of pramipexole , which was partly supported by a recent RCT .”

Introduction ¶3Find in source

paraphrase[Introduction, paragraph 2]

“Together, these multimodal assessments were designed to provide a comprehensive evaluation of pramipexole’s clinical efficacy and mechanistic effects on anhedonia.”

Introduction ¶4Find in source

Sub-criteria

controlsN/A

power analysisADEQUATE

blinding levelsADEQUATE

outlier handlingADEQUATE

randomization unitADEQUATE

inclusion exclusionADEQUATE

randomization methodADEQUATE

replicate distinctionN/A

independent replicationN/A

Per reviewer (2) — the votes behind the verdict

PASSReviewer 1· 95% conf

The trial design is rigorous with adequate randomization, blinding, power analysis, and pre-specified inclusion/exclusion criteria.

Evidence

“The block size varied randomly between 4 and 6, and the order within the blocks was generated randomly using a computer-based algorithm.”

MethodsFind in source

“To maintain blinding in the RCT, a separate team of study physicians and nurses conducted the open-label extension phase.”

MethodsFind in source

PASSReviewer 2· 95% conf

Evidence

paraphrase[Methods, Trial design and Intervention]

“Patients, research physicians and nurses involved in patient assessments were blinded for treatment allocation.”

MethodsFind in source

Sub-criteria

demographicsADEQUATE

sex reportedADEQUATE

sex justifiedN/A

age weight healthADEQUATE

housing conditionsN/A

species strain sourceN/A

Per reviewer (2) — the votes behind the verdict

PASSReviewer 1· 90% conf

Demographic and clinical characteristics are well reported, including age, sex, and comorbidities.

Evidence

“Thirty-seven (45.12%) participants were female.”

ResultsFind in source

“Age, mean (s.d.) | 47.44 (13.14) | 47.00 (14.32) | 47.22 (13.66)”

Table 1Find in source

“Percent anxiety disorder | 39.02% ( n = 16) | 39.02% ( n = 16) | 39.02% ( n = 32)”

Table 1Find in source

PASSReviewer 2· 90% conf

Evidence

“Age, mean (s.d.) | 47.44 (13.14) | 47.00 (14.32) | 47.22 (13.66) | | Percent women (self-reported) | 46.34% ( n = 19) | 43.90% ( n = 18) | 45.12% ( n = 37)”

Table 1Find in source

“Percent anxiety disorder | 39.02% ( n = 16) | 39.02% ( n = 16) | 39.02% ( n = 32)”

Table 1Find in source

Sub-criteria

iacuc statementN/A

informed consentADEQUATE

irb ethics statementINADEQUATE

regulatory complianceADEQUATE

Per reviewer (2) — the votes behind the verdict

PASSReviewer 1· 85% conf

Ethical approval and informed consent are adequately reported.

Evidence

“All participants provided written informed consent prior to study participation.”

MethodsFind in source

Data availabilityFind in source

absence[Methods]

Specific ethics committee name is not explicitly stated in the provided text.

PASSReviewer 2· 85% conf

The study reports ethics approval and informed consent, and is registered. The ethics statement is adequate, though the specific IRB name is not given in the text.

Evidence

“All participants provided written informed consent prior to study participation.”

MethodsFind in source

“Deidentified participant data underlying the findings of this study will be made available from the corresponding author, subject to approval by the relevant institutional ethics committee”

Data availabilityFind in source

“ClinicalTrials.gov identifiers: NCT05355337 (http://clinicaltrials.gov/study/NCT05355337) and NCT05825235 (http://clinicaltrials.gov/study/NCT05825235) .”

AbstractFind in source

Sub-criteria

mycoplasma testingN/A

reagents identifiedADEQUATE

organisms identifiedN/A

antibodies identifiedN/A

cell line authenticationN/A

software tools identifiedADEQUATE

Per reviewer (2) — the votes behind the verdict

PASSReviewer 1· 90% conf

The investigational product (pramipexole) and placebo are adequately identified, and statistical software is specified.

Evidence

“Extended-release pramipexole tablets from STADA Nordic were labeled and repackaged consistent with European Union guidelines and Good Manufacturing Practice (GMP).”

MethodsFind in source

Statistical analysisFind in source

PASSReviewer 2· 90% conf

The investigational product (pramipexole) and placebo are identified with manufacturer and formulation, and statistical software is identified. No other biological/chemical resources are used.

Evidence

MethodsFind in source

Statistical analysisFind in source

Sub-criteria

tests namedADEQUATE

exact p valuesADEQUATE

effect sizes ciADEQUATE

data presentationADEQUATE

software identifiedADEQUATE

assumptions verifiedADEQUATE

mathematical plausibilityN/A

Per reviewer (2) — the votes behind the verdict

PASSReviewer 1· 90% conf

Statistical methods are appropriate and well-reported, with exact p-values and effect sizes with confidence intervals.

Evidence

“The difference in mean change was −4.04 (95% confidence interval: −6.89 to −1.18, P = 0.006, Hedges’ g = 0.62).”

ResultsFind in source

“The difference in mean change was −4.04 (95% confidence interval: −6.89 to −1.18, P = 0.006, Hedges’ g = 0.62).”

ResultsFind in source

Statistical analysisFind in source

PASSReviewer 2· 90% conf

Statistical methods are well described, with named tests, effect sizes with confidence intervals, and software identified. The primary analysis uses a mixed model with exact p-values and CIs.

Evidence

“The difference in mean change was −4.04 (95% confidence interval: −6.89 to −1.18, P = 0.006, Hedges’ g = 0.62).”

ResultsFind in source

Statistical analysisFind in source

“Group means are represented by solid lines, with shaded ribbons indicating ±1 s.e.”

Figure 2Find in source

Sub-criteria

code sharingADEQUATE

accession numbersN/A

repository depositN/A

data availability statementADEQUATE

Per reviewer (2) — the votes behind the verdict

PASSReviewer 1· 95% conf

Data availability statement is concrete, and code is shared in a public repository.

Evidence

Data availabilityFind in source

“The SAS syntax and R scripts used for the analyses in this study are publicly available under the MIT license at https://github.com/UnitforBAPP/PRIME-PRAXOL_RCT/”

Data availabilityFind in source

PASSReviewer 2· 95% conf

Evidence

Data availabilityFind in source

Sub-criteria

funding coiADEQUATE

trial registrationADEQUATE

reporting guidelineADEQUATE

methods completenessADEQUATE

all outcomes reportedADEQUATE

limitations discussedADEQUATE

conclusions proportionalADEQUATE

Per reviewer (2) — the votes behind the verdict

PASSReviewer 1· 95% conf

The manuscript is transparent with trial registration, reporting guidelines, limitations, and funding/COI statements.

Evidence

paraphrase[Abstract]

“ClinicalTrials.gov identifiers: NCT05355337 (http://clinicaltrials.gov/study/NCT05355337) and NCT05825235 (http://clinicaltrials.gov/study/NCT05825235).”

“Supplementary Information Supplementary Tables 1–5, Fig. 1, Data 1 and 2, study protocol, statistical analysis plan and CONSORT checklist.”

Supplementary materialFind in source

“Another limitation is that we did not adjust for multiplicity across secondary outcomes, increasing the risk of type I error and warranting cautious interpretation of these findings.”

Discussion ¶10Find in source

PASSReviewer 2· 90% conf

The manuscript is transparent: methods are detailed, the trial is registered, a CONSORT checklist is provided, limitations are discussed, and funding/COI are disclosed.

Evidence

“ClinicalTrials.gov identifiers: NCT05355337 (http://clinicaltrials.gov/study/NCT05355337) and NCT05825235 (http://clinicaltrials.gov/study/NCT05825235) .”

AbstractFind in source

“Another limitation is that we did not adjust for multiplicity across secondary outcomes, increasing the risk of type I error and warranting cautious interpretation of these findings.”

Discussion ¶8Find in source

paraphrase[Funding and Competing interests]

“The study has received funding from the Swedish Research Council (grant number 2020-01428); ... The other authors declare no competing interests.”

Registered (4 IDs: ClinicalTrials.gov, EudraCT). Reporting guideline cited: CONSORT.

Broken references and links

None found

References checked against Crossref, OpenAlex and Retraction Watch for retractions and resolvability, plus declared data and code links probed for whether they resolve to content matching the paper.

Checked — nothing surfaced.

Checked 68 references by DOI: 63 verified — 5 no DOI (shown, not verified).

4 data/code links checked; 4 live.

Copyediting

4 minor

Wording, consistency and formatting errors that need correcting before submission.

No major wording or formatting errors. 4 minor suggestions below.

4 copyedit issues flagged: mostly consistency, other.

Kaimen Rigor Action ItemsFinal pass before journal submission

1.
HIGHethics
In the Methods/Ethics section, explicitly name the institutional ethics committee (e.g., Swedish Ethical Review Authority) and provide the approval number.
The current ethics statement is incomplete, which is a reporting gap that readers and journals expect to be filled.
2.
HIGHreporting
In the Methods, provide the specific power analysis parameters (assumed effect size, alpha, power) used to determine the sample size.
The text only references a pilot study; full documentation of the power analysis strengthens the sample size justification.
3.
MEDIUMreporting
In the Results, clarify the blinding-integrity numbers: the text states 66.66% correct guesses in the placebo group but also reports n=26 correct guesses out of 41 participants, which is inconsistent (66.66% of 41 ≈ 27.3).
This minor discrepancy could confuse readers and should be reconciled or explained.
4.
MEDIUMreporting
In the Results, report the exact p-values for the chi-square tests on response and remission rates (currently reported as P ≥ 0.283 and P ≥ 0.655).
Exact p-values improve precision and transparency.
5.
MEDIUMreporting
In the Methods, clarify the exact definition of the modified intention-to-treat population, including how the three excluded participants were handled in sensitivity analyses.
This clarifies the analysis population and enhances reproducibility.
6.
MEDIUMreporting
In the Results, report the exact p-values for the blinding integrity test in the placebo group (P = 0.053) and the pramipexole group (P = 0.117) in the main text, as they are only in the supplementary.
Blinding integrity is a key quality metric; reporting exact p-values in the main text improves transparency.
7.
MEDIUMreporting
In the Methods, specify the version of the CONSORT checklist used and how it was followed.
This enhances transparency regarding adherence to reporting guidelines.
8.
MEDIUMreporting
In the Results, for the fMRI substudy, report the number of participants excluded for each reason.
This improves transparency about missing data in the substudy.
9.
MEDIUMreporting
In the Discussion, consider discussing the potential impact of the imbalance in SNRI use between groups on the primary outcome, even though post hoc analyses suggested no effect.
Addressing this potential confounder strengthens the interpretation.
10.
MEDIUMreporting
In the Methods, clarify the handling of missing data for the fMRI substudy and other exploratory outcomes, as the main analysis used MMRM but the substudy analyses may have used complete-case analysis.
Clarifying missing data handling for all analyses improves reproducibility.
11.
LOWcopyedit
In the Abstract, rephrase the sentence 'Pramipexole, in patients with major depressive disorder, dysthymia or bipolar depression, reduced Snaith−Hamilton Pleasure Scale scores significantly compared to placebo.' for clarity.
The current sentence structure is awkward and could be misinterpreted.
12.
LOWcopyedit
In the Results, Safety RCT phase, verify that the percentages for sleep disturbances (72.09% versus 33.33%) are consistent with the denominators (e.g., 72.09% of 43 = 31, 33.33% of 42 = 14) and consider adding counts.
Ensuring percentage-count consistency avoids potential confusion.
13.
LOWdata code
In the Data Availability statement, consider specifying the exact contact email or data access committee to further clarify the access route.
This minor addition would make the data access process more concrete.

Full text (92,832 chars · analyzed ~81%, head + tail)Analyzed: Aug 15, 2026