Reduced striatal dopamine transmission as a transdiagnostic substrate of psychomotor retardation
Bibliographic record
Abstract
Psychomotor retardation, defined as generalized slowing of movement and speech, is a feature of several neurological and psychiatric disorders. In this review, we discuss the hypothesis that reduced striatal dopaminergic transmission is a transdiagnostic substrate for psychomotor retardation underlying the motor features of conditions such as Parkinson's disease, drug-induced parkinsonism, neuroleptic malignant syndrome, catatonia and depression. We examine the evidence across clinical, epidemiological, neuroimaging, laboratory and therapeutic studies. Parkinsonian disorders share slowed movement and a reduction in verbal output with catatonia and depression. Bradyphrenia, slowed cognitive processing, also occurs in Parkinson's disease and depression. In addition, there are close epidemiological relationships between depression and Parkinson's disease, and between catatonia and neuroleptic malignant syndrome. Neuroimaging studies also generally support the association of psychomotor retardation with reduced dopaminergic transmission, particularly in the dorsal striatum. CSF measurement of homovanillic acid (a dopamine catabolite) yields inconsistent results and is non-specific. Parkinson's disease and catatonia generally respond well to dopaminergic medication. In contrast, dopamine antagonists can induce both parkinsonism and catatonia. Our review is limited by the variability in measurement of psychomotor retardation and difficulty distinguishing between cognitive and motor slowing. It is also likely that other neurotransmitters, such as GABA and serotonin, play an important role in psychomotor speed. It is possible that dopaminergic deficits in psychiatric disorders represent functional disruptions, in contrast to the structural damage to the substantia nigra in Parkinson's disease. We propose further research be conducted into the effects of levodopa and dopamine agonists in depression with psychomotor retardation. Alternative neuroimaging methods such as PET sequences with shorter imaging protocols and neuromelanin-MRI should also be explored.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| 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 | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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 teacher head, 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".