An Exploratory Investigation of Trait Anhedonia and Its Correlates Across the Schizophrenia Spectrum
Bibliographic record
Abstract
Anhedonia, the reduced capacity to experience pleasure, has long been considered a core negative symptom of schizophrenia. However, while people with schizophrenia consistently report anhedonia on trait questionnaires, they also consistently report intact state pleasure relative to healthy controls. Several theories have been proposed to reconcile this apparent paradox within the schizophrenia literature. Recent work grounded in the evaluative space model, a theory of the motivational underpinnings of the positive and negative emotional valence systems, is showing promise in better understanding state-trait discrepancies in this population. The current dissertation includes four studies designed to better understand, and improve the convergent validity between, state and trait pleasure assessments in people with schizophrenia. Study 1 is a systematic review and meta-analysis of 146 studies showing that samples of people with schizophrenia ubiquitously report elevated trait anhedonia relative to healthy controls. Moderator analyses showed that clinical and demographic characteristics weakly predicted trait anhedonia effect sizes. Using Exploratory Structural Equation Modelling (ESEM) in 2250 Canadian and American Prolific volunteers, Study 2 refined existing items from trait anhedonia measures identified in Study 1 and validated them against positive and negative response tendencies to develop a trait anhedonia measure grounded in the evaluative space model. It also showed measurement invariance across differing scale types, sex, age, and positive schizotypal personality features. Using a multi-trait multi-method ESEM approach in 1305 Prolific volunteers, Study 3 showed that the refined measure of trait anhedonia is moderately correlated with state pleasure using stimuli from the International Affective Picture System, suggesting that state and trait anhedonia are related but not equivalent constructs. Finally, Study 4 tested the validity of the refined measure of trait anhedonia in 50 people with schizophrenia and 48 community controls. Although state-trait discrepancies remained using a previously validated measure of trait anhedonia, there were no significant between-group differences in state or trait anhedonia using the refined measure. Moreover, coactivation of state positive and negative emotions significantly predicted trait anhedonia. Based on these results, candidate mechanisms for trait anhedonia in schizophrenia and associated treatment considerations are discussed, including emotional ambivalence, biased expectations and beliefs, shifting values, and neurocognition.
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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 | 0.003 | 0.005 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.002 | 0.002 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| 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".