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  "slug": "brain-disease-measured-not-just-named",
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  "newsroom_title": "Health & Biotech",
  "angle": "Brain-disease work is shifting from one test per diagnosis to shared, calibrated measures",
  "headline": "Brain disease is getting measured, not just named: a blood test, a trial design and a shared signal",
  "dek": "A blood marker for amyloid works better with locally tuned cutoffs, a platform trial borrows registry data to test more drugs, and one brain signal shows up across three kinds of psychiatric risk.",
  "published_at": "2026-11-07T00:39:43Z",
  "labels": {
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    "trust_text": "Reported · 3 Manifests",
    "newsroom": "Health & Biotech"
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    {
      "text": "In a preprint in 205 Singaporean participants with high cerebrovascular disease burden, the plasma pTau217/Aβ42 ratio detected amyloid pathology with an AUC of 0.951, against 0.925 for pTau217 alone.",
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      "text": "In the same preprint, locally optimised cutoffs reached 95% accuracy and 88% positive predictive value, against 85% accuracy and 77% with FDA-cleared cutoffs, and cut intermediate-risk classifications from 29% to 10%.",
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      "text": "In a preprint, the Path to Prevention platform trial design supplements randomised placebo data with Parkinson's Precision Medicine Initiative registry data, raising statistical power by up to 4%, and is powered to detect a 40% slowing in progression.",
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      "text": "In a preprint meta-analysis of 101 task-based fMRI studies with 2,534 high-risk and 2,686 control participants, increased activation in the left lateral prefrontal cortex was a shared alteration across mood, anxiety and psychotic disorder risk groups.",
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  "sections": [
    {
      "heading": "What changed",
      "paragraphs": [
        {
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          "markdown": "Three preprints posted this week approach brain disease from the same angle: stop arguing about the label, and fix the measurement. One recalibrates a blood test for Alzheimer's amyloid pathology in a population where the standard cutoffs underperform. One redesigns how early Parkinson's-like disease trials are run, so several drugs can be tested inside one standing trial. And one pools 101 brain-imaging studies to find a signal shared across mood, anxiety and psychotic disorder risk, rather than a marker for any single diagnosis."
        },
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          "markdown": "The common thread is calibration. A test, a trial design and a brain signal are all only as good as the population and the comparison they were tuned on, and all three papers show what happens when that tuning is made explicit. The blood test needs local cutoffs. The trial needs a control group assembled from more than its own randomised patients. And the imaging signal needs to survive across different ways of defining who is at risk before it can be trusted."
        }
      ]
    },
    {
      "heading": "A blood test that needs local tuning",
      "paragraphs": [
        {
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          "markdown": "The blood-test preprint evaluated the Lumipulse plasma pTau217/Aβ42 ratio in 205 Singaporean participants with high cerebrovascular disease burden, checking the blood marker against amyloid neuroimaging. The ratio outperformed pTau217 alone for detecting amyloid pathology, with an area under the curve of 0.951 against 0.925. That is the headline result, but the more consequential finding concerns the cutoffs: the FDA-cleared cutoffs showed lower specificity, 86%, and lower accuracy, 85%, in this cohort than locally optimised cutoffs, which reached 95% accuracy."
        },
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          "markdown": "The practical difference shows up in the grey zone. With the FDA-cleared cutoffs, 29% of the cohort fell into an intermediate-risk classification, against 10% with the optimised cutoffs, and positive predictive value rose from 77% to 88% with local tuning. This suggests a blood test that looks settled on paper can leave nearly a third of patients in an uncertain middle when it is used in a population it was not tuned for. The study has no external validation in other Asian cohorts and was limited to Singapore-based participants, so the locally tuned cutoffs are a demonstration that calibration matters, not a new standard to adopt elsewhere."
        }
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    },
    {
      "heading": "A trial built to keep running",
      "paragraphs": [
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          "markdown": "The Path to Prevention trial, known as P2P, is a design paper rather than a report of results: it lays out a perpetual phase 2A platform trial for early neuronal alpha-synuclein disease, embedded in the Parkinson's Precision Medicine Initiative. The design uses a longitudinal Bayesian mixed-effects model to compare active treatment against shared placebo controls, with dynamic discounting of non-randomised data. Supplementing the randomised control data with non-randomised PPMI registry data increases statistical power by up to 4% for the primary endpoints, and the trial is powered to detect a 40% slowing in progression on both DAT SPECT and MDS-UPDRS Part III."
        },
        {
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          "markdown": "The point of the perpetual platform is that the infrastructure stays in place while investigational therapies come and go, so several candidates can be tested concurrently instead of each one requiring a fresh trial to be built. The design was tested in simulations using a PPMI cohort of 275 participants, with treated follow-up of 96 to 144 weeks. Because this is a design paper, it proves nothing about any drug; what it offers is a way to run early neurodegeneration trials faster, at the cost of relying on registry data that has to be discounted carefully rather than treated as equal to randomised controls."
        }
      ]
    },
    {
      "heading": "One signal across three kinds of risk",
      "paragraphs": [
        {
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          "markdown": "The imaging preprint is a meta-analysis of 101 task-based functional MRI studies, covering 2,534 high-risk participants and 2,686 controls, using activation likelihood estimation to find brain alterations shared across risk for mood, anxiety and psychotic disorders. It found increased activation in the left lateral prefrontal cortex across all three risk groups, with a cluster size of 319, and the finding held across both familial and phenotypic ways of defining risk, and across cognitive, affective and reward tasks."
        },
        {
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          "markdown": "This suggests executive-function regions of the brain may carry a shared marker of psychiatric vulnerability that does not respect diagnostic boundaries, which is the transdiagnostic idea in its simplest form. The limitation is stated plainly in the preprint: there are no longitudinal data to confirm whether this marker predicts who will go on to develop a disorder, and the studies pooled together varied in task types and in how risk was defined, which may influence the size of the effect. A shared signal is a place to start looking, not a test anyone can order, and the next step is following people over time rather than pooling more snapshots."
        }
      ]
    }
  ],
  "unresolved": [
    "All three papers are preprints, not yet peer reviewed.",
    "The pTau217 cutoffs have no external validation in other Asian cohorts and were tested only in Singapore-based participants.",
    "The Path to Prevention paper is a trial design only; it reports no clinical trial results.",
    "There are no longitudinal data confirming that the shared prefrontal signal predicts future disorder onset."
  ],
  "decision_card": {
    "not_for": [
      "Clinical diagnosis on the basis of any of these preprints",
      "Treating locally optimised cutoffs as a general standard",
      "Treating the shared imaging signal as a predictive test"
    ],
    "useful_for": [
      "Clinicians and labs adopting blood-based amyloid biomarkers in diverse populations",
      "Trial designers working on early neurodegenerative disease",
      "Researchers studying shared mechanisms across psychiatric disorders"
    ],
    "compare_against": [
      "FDA-cleared Lumipulse cutoffs for pTau217/Aβ42",
      "Standalone randomised trials for each candidate therapy",
      "Single-diagnosis imaging markers"
    ]
  },
  "writer": {
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    "run_id": "2026-11-07T00"
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      "title": "Optimizing Lumipulse plasma pTau217/Aβ42 ratio cutpoints in an Asian cohort with high cerebrovascular disease burden",
      "source_url": "https://medrxiv.org/content/10.64898/2026.11.04.26367313v1.full",
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