M81. Atypical Antipsychotic Dose-Dependent Effects on Fractional Anisotropy in a Cohort of Chronic Schizophrenia Patients
Bibliographic record
Abstract
Background: The neurotoxic and/or neuroprotective effects of individual antipsychotics remain controversial, with equivocal reports emerging from the animal and human literature, particularly in cognitively critical fronto-temporal areas. We investigated the relationship between antipsychotic dose and frontal white matter fractional anisotropy (FA) to determine potential neurotoxicity of atypical antipsychotics and the relationships between white matter FA, symptom severity and cognition. Methods: 3T diffusion imaging was performed in 10 chronic DSM-V schizoaffective and 9 schizophrenia patients (mean age 30.6 yr: 6 F, 13 M). Symptom severity was assessed with the PANSS (mean score = 96.1). Cognitive measures included Trails A & B, the Hopkins Verbal Learning Test and the Symbol Digit Modalities Test. Patients were being treated with a mix of one or more atypical medications (aripriprazole, clozapine, olanzapine, quetiapine, palliperidone, risperidone). Fractional anisotropy (FA) of the major frontal tracts (genu, fornix, bilateral anterior limb internal capsule, bilateral superior longitudinal fasciculus—SLF) was extracted with FSLv5.3 FMRIB and co-registered to the JHU DTI atlas prior to FreeSurfer 5.0 segmentation. Exploratory linear regressions were used to probe regions prior to specific region-of-interest analysis of variance. Bonferroni correction was applied at the .01 level. Results: One dataset was omitted due to poor imaging quality. Mean chlorpromazine equivalent (CPZE) dose was 680.2 mg/d. Mean duration of illness = 10.1 years. Strong inverse relationships were observed between FA in the left SLF (r = −.654, F(17,1) = 12.7, P = .0024) and the fornix body (r = −.651, F(17,1) = 12.5, P = .0025) and CPZE dose. These relationships were not associated with age, PANSS scores or cognitive measures (P > .05). FA values in all other regions of interest were not significantly correlated to any other measures of interest. Conclusion: In vitro investigations suggested that atypical neuroleptics, particularly clozapine, may be associated with increased cerebral cell death The inverse association of reduced FA signal in the SLF and the fornix with antipsychotic dose suggests a dose-dependent alteration in axonal permeability in patients receiving atypical medications, however, this change in FA signal is not necessarily a direct measure of neuronal pathology.
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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 | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.003 | 0.001 |
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".