Fatty acid amide hydrolase in major depressive episodes: A [11C]CURB positron emission tomography study
Bibliographic record
Abstract
Abstract The role of the endocannabinoid system (ECS) in major depressive disorder (MDD) is under-investigated despite reports of increased activity and/or concentration of fatty acid amide hydrolase (FAAH), a key ECS enzyme, in fronto-limbic brain regions in some animal models of depressive behavior. We hypothesized that [11C]CURB λk 3, an index of FAAH density, would be elevated in the prefrontal cortex, hippocampus, and anterior cingulate cortex in major depressive episodes of MDD compared to healthy controls. Fifteen unmedicated MDD participants and 15 age- and sex-matched healthy controls underwent [11C]CURB positron emission tomography and FAAH genotyping. Psychological tests of depressive severity, apathy, and anxiety were administered and measurements were assessed as covariates in exploratory analyses. No significant group differences in [11C]CURB λk 3 were observed between MDD participants and controls (F 1,27 = 0.32; p = 0.58). A mixed effects model revealed that Marin Apathy Evaluation Scale scores in the MDD group had a significant main effect on [11C]CURB λk 3 binding across the collective regions of medial prefrontal cortex, orbitofrontal cortex, anterior cingulate cortex, ventral striatum, and midbrain (F 1,11 = 6.75; p = 0.02). Depressive severity and anxiety did not have a significant relationship to [11C]CURB λk 3 binding. The relationship of greater fronto-limbic [11C]CURB λk 3 to greater apathy along with the metabolic role of FAAH in the ECS, the latter which supports maintaining feelings of interest, initiative, and motivation, has important implications for the pathophysiology of apathy in MDD.
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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) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 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".