Every antipsychotic drug tested to date modulates microtubule biology, yet no formal hypothesis hasproposed this as the primary therapeutic mechanism. Here I assemble converging evidence — spanningdirect tubulin binding, MAP2 expression changes, GSK-3β pathway inhibition, cytoskeletal genetics, andthe MAP6/STOP knockout mouse model — to argue that antipsychotic efficacy derives primarily fromnormalization of pathologically altered microtubule dynamics, with dopamine D2 receptor blockaderepresenting a pharmacologically prominent but therapeutically secondary effect. A newly constructedcomposite microtubule-modulating score integrating four independent mechanisms correlates positivelywith antipsychotic clinical efficacy (standardized mean difference, SMD; r = +0.49, n = 7), while D2receptor affinity correlates negatively with efficacy (r = −0.53). A controlled within-class analysis of CF3substituted phenothiazine/thioxanthene pairs (4/4 concordant) provides independent structuralpharmacological support. This hypothesis resolves three longstanding puzzles: (1) why clozapine, themost effective antipsychotic, has the weakest D2 affinity; (2) why 30–50% of patients are treatmentresistant to D2-blocking agents; and (3) why the MAP6/STOP knockout mouse — a purely cytoskeletalmodel — produces a complete schizophrenia phenotype including downstream dopamine dysregulation.The critical experiment — systematic nanoDSF screening of second-generation antipsychotics combinedwith a prospective clinical trial of MT-normalizing agents in “D2-responsive” patients — is now bothfeasible and urgently indicated.
Marko Leicht (Fri,) studied this question.