SCZ-001
Schizophrenia · Dopamine D2 / NMDA Hypofunction Engine · VIZASL v1
MEBICAL · EOSE Fleet · TRB-MEBICAL-HEALTH-DOMAIN-001 · Day 90 · Real data · Cited · Sorries marked
MEBICAL · PSYCH ← RESEARCH
Mesolimbic DA hyperactivation (positive sx)
NMDA hypofunction (PV+ interneuron)
γ-band disruption rings (40Hz deficit)
Hypoactive PFC (negative sx)
γ₁ floor anchor
PHASES
RX
BIOMARKERS
EEG
NPs
Two-Hit Hypothesis
Hit 1: Mesolimbic DA Hyperactivation (Positive Symptoms)
Dopamine excess in mesolimbic pathway (VTA → nucleus accumbens → limbic cortex). Drives positive symptoms: hallucinations, delusions, disorganised speech. ALL antipsychotics block D2 receptors. This is why D2 blockade = antipsychotic effect. PET: presynaptic DA synthesis elevated 2–3× in SCZ.
Carlsson & Lindqvist 1963 (DA hypothesis) · Laruelle et al. 1996 (PET DA elevation)
Hit 2: Prefrontal DA Hypoactivation (Negative Symptoms)
Dopamine deficit in mesocortical pathway (VTA → PFC). Drives negative symptoms: flat affect, anhedonia, alogia, avolition. Cognitive impairment. PFC D1 receptor hypostimulation = working memory failure. D2 blockade doesn't help (makes worse). This is the real disability.
Weinberger 1987 (hypofrontality) · Goldman-Rakic 1995 (D1/working memory)
NMDA Hypofunction Hypothesis
PCP and ketamine (NMDA antagonists) mimic schizophrenia. Both positive AND negative symptoms. NMDA hypofunction on PV+ GABAergic interneurons → disinhibition → DA surge → γ-band disruption. Explains both symptom domains from one mechanism. Glycine site agonists (glycine, D-serine) target this.
Javitt & Zukin 1991 (PCP model) · Coyle 2006 (NMDA hypothesis)
PV+ Interneuron Loss
Parvalbumin-positive GABAergic fast-spiking interneurons reduced in PFC + hippocampus at autopsy. These cells synchronise γ-oscillations. Their loss = γ-band deficit = cognitive desynchronisation. Proposed as final common pathway of NMDA hypofunction → γ loss.
Lewis et al. 2005 Nat Rev Neurosci (PV+ interneurons)
Polygenic Risk — No Single Gene
100+ GWAS loci. All tiny effect sizes. DISC1, CACNA1C, COMT, 22q11 deletion (22q11DS = 30× SCZ risk). No single genetic test diagnostic. Schizophrenia is a polygenic syndrome, not a single disease. SORRY: genetic architecture implies >100 biological mechanisms, all contributing small amounts.
Ripke et al. 2014 Nature (108 loci GWAS)
Antipsychotics PROVEN for Positive Symptoms
Clozapine — Most Effective for TRS
Treatment-resistant schizophrenia (TRS = 30%). D4 + serotonin antagonism (not just D2). Kane 1988: clozapine 30% response in TRS vs 4% chlorpromazine. Agranulocytosis risk (1–3%) — mandatory WBC monitoring. Mechanism poorly understood. SORRY: why clozapine works for TRS when others fail is unknown.
Kane et al. 1988 Arch Gen Psychiatry (clozapine vs chlorpromazine)
Atypicals (Olanzapine, Risperidone)
D2 + 5-HT2A blockade. Lower EPS than typicals. Metabolic side effects (weight gain, diabetes). Risperidone: most studied. Olanzapine: effective but most metabolic risk. Aripiprazole: D2 partial agonist — different mechanism.
Leucht et al. 2013 Lancet (meta-analysis of antipsychotics)
No Drug for Negative Symptoms or Cognition SORRY
Negative symptoms (flat affect, anhedonia, avolition) and cognitive impairment are the MAIN drivers of disability. No approved drug treats them. Negative symptoms respond poorly or not at all to antipsychotics. The real unmet need in schizophrenia.
SORRY: TURNS trial, CATIE, CUtLASS — all show cognitive + negative sx remain untreated
Biomarker Status NO VALIDATED DIAGNOSTIC
40Hz ASSRAuditory steady-state response at 40Hz. Reduced in SCZ. Most replicated EEG biomarker. Reflects PV+ interneuron → γ-oscillation deficit. Research biomarker, not yet clinical. Uhlhaas & Singer 2010
MMN reductionMismatch negativity. Reduced amplitude in SCZ. Automatic deviation detection deficit. Correlates with functional outcome. SORRY: not diagnostic.
Structural MRIReduced grey matter (PFC, temporal lobe), enlarged lateral ventricles. Present at first episode. Group-level finding, not diagnostic for individuals.
Polygenic risk scorePRS from 108 GWAS loci. Research use. Low individual predictive value. Cannot diagnose.
Open Sorries
SORRY-1: D2 hypothesis explains antipsychotic mechanism but not disease causation. Not all SCZ patients have elevated DA.
SORRY-2: No drug for negative symptoms or cognitive impairment — the main disability.
SORRY-3: γ-band deficit mechanism (PV+ interneuron loss) not yet targetable.
SORRY-4: Clozapine TRS mechanism unknown despite 35yr of use.
SORRY-5: Why antipsychotics take 2–4 weeks for full effect despite immediate D2 blockade is unknown.
EEG Signatures — Schizophrenia
γ-deficit 40Hz STRONGReduced 40Hz ASSR (auditory steady-state response). Same EEG SIGNATURE as AD γ-loss. DIFFERENT MECHANISM: SCZ = PV+ interneuron loss from NMDA hypofunction. AD = GABAergic interneuron loss from neurodegeneration. Different cause, same oscillation band. Uhlhaas & Singer 2010 Nat Rev Neurosci
MMN↓Mismatch negativity reduction. Automatic change detection. Pre-attentive auditory processing deficit. Correlates with functional outcome better than PANSS.
P300 amplitude↓P300 reduction = attention/working memory deficit. Correlates with negative symptoms. State-independent trait marker.
γ vs AD γCRITICAL NOTE: SCZ and AD both show γ-band deficit. SCZ = PV+ interneuron dysfunction (NMDA-mediated). AD = GABAergic interneuron loss (amyloid/tau). Same EEG finding, different biology, different therapeutic target.
Novel Patterns (8)
PROVENNP-SCZ-001 · Two-hit: mesolimbic DA excess (positive sx) + mesocortical DA deficit (negative sx) = same disease, opposite directions in different circuits
PROVENNP-SCZ-002 · PCP/ketamine mimics BOTH positive AND negative symptoms via NMDA blockade — strongest evidence for NMDA hypofunction hypothesis
PROVENNP-SCZ-003 · Clozapine 30% TRS response when all other drugs fail · D4 mechanism not D2 · mechanism unknown · 35yr of use · SORRY: still don't know why
PROVENNP-SCZ-004 · 40Hz ASSR γ-deficit = SAME EEG signature as AD · DIFFERENT MECHANISM · SCZ=PV+ NMDA · AD=GABAergic neurodegeneration · oscillation convergence, biology divergence
OPENNP-SCZ-005 · PV+ interneuron rescue: glycine site agonists (D-serine, glycine) target NMDA hypofunction · Phase 2/3 trials · could restore γ-oscillations
OPENNP-SCZ-006 · 22q11 deletion syndrome: 30× SCZ risk, 25% develop SCZ · strongest single genetic risk · reveals developmental origin of schizophrenia
SORRYNP-SCZ-007 · No treatment for negative symptoms/cognition (the real disability) · clozapine mechanism unknown · 2-4 week antipsychotic delay unexplained · no biomarker
SORRYNP-SCZ-008 · Polygenic architecture: 100+ loci, all tiny effects · implies 100+ biological mechanisms · no single drug target covers the disease · paradigm problem
⚠ OPEN SORRIES · SCZ-001
SORRY-1 · No treatment for negative symptoms/cognition
Negative symptoms (flat affect, avolition, anhedonia) and cognitive impairment (working memory, executive function) are the primary drivers of disability in schizophrenia. No approved drug treats them. Antipsychotics target positive symptoms only.

SORRY-2 · D2 hypothesis explains mechanism, not disease
All antipsychotics block D2. This explains why they work. But not all schizophrenia patients show elevated dopamine on PET. D2 is the drug target, not necessarily the disease cause.

SORRY-3 · Clozapine mechanism unknown
Clozapine has been used for 35 years and is the most effective drug for TRS. Its mechanism is still not understood. D4 blockade? Serotonin? Immune modulation? All proposed, none definitive.

SORRY-4 · Antipsychotic delay mystery
D2 receptors are blocked within hours of the first antipsychotic dose. But clinical antipsychotic effect takes 2–4 weeks. The biology of why immediate receptor blockade produces delayed clinical response is unexplained.

SORRY-5 · γ-band: same signature, different disease
SCZ and AD share the 40Hz γ-band deficit signature on EEG. But the mechanisms are entirely different. Using EEG alone cannot distinguish these diseases. The oscillation convergence is a red herring for diagnosis.
SCZ-001 · DA TWO-HIT · NMDA HYPOFUNCTION · PV+ INTERNEURON LOSS · γ-DEFICIT ≠ AD γ-DEFICIT · NO NEGATIVE SX TREATMENT
γ₁ = 14.134725141734693