The<scp>D</scp><sub>2/3</sub>dopamine receptor in pathological gambling: a positron emission tomography study with [<sup>11</sup><scp>C</scp>]‐(+)‐propyl‐hexahydro‐naphtho‐oxazin and [<sup>11</sup><scp>C</scp>]raclopride
Bibliographic record
Abstract
AIMS: Pathological gambling (PG) shares diagnostic features with substance use disorder (SUD), but the neurochemical mechanisms underlying PG are poorly understood. Because dopamine (DA), a neurotransmitter implicated in reward and reinforcement, is probably involved, we used positron emission tomography (PET) to test whether PG is associated with abnormalities in D2 and D3 receptor levels, as observed in SUD. DESIGN: Case-control study comparing PG to healthy control (HC) subjects. SETTING: Academic research imaging centre. PARTICIPANTS: Thirteen non-treatment-seeking males meeting DSM-IV criteria for PG, and 12 matched HC (11 of whom completed PET). MEASUREMENTS: Two PET scans (one with the D3 receptor preferring agonist [11C]-(+)-propyl-hexahydro-naphtho-oxazin (PHNO) and the other with [11C]raclopride) to assess D(2/3) DA receptor availability, and behavioural measures (self-report questionnaires and slot-machine game) to assess subjective effects and relationships to PET measures. FINDINGS: Binding of both radiotracers did not differ between groups in striatum or substantia nigra (SN) (all P > 0.1). Across PG, [11C]-(+)-PHNO binding in SN, where the signal is attributable primarily to D3 receptors, correlated with gambling severity (r = 0.57, P = 0.04) and impulsiveness (r = 0.65, P = 0.03). In HC, [11C]raclopride binding in dorsal striatum correlated inversely with subjective effects of gambling (r = -0.70, P = 0.03) and impulsiveness (r = -0.70, P = 0.03). CONCLUSIONS: Unlike with substance use disorder, there appear to be no marked differences in D2 /D3 levels between healthy subjects and pathological gamblers, suggesting that low receptor availability may not be a necessary feature of addiction. However, relationships between [11C]-(+)-PHNO binding and gambling severity/impulsiveness suggests involvement of the D3 receptor in impulsive/compulsive behaviours.
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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 | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.001 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| 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".