Treatment-Resistant Schizophrenia: Acting Early, Looking Beyond Dopamine
Treatment-resistant schizophrenia (TRS) impacts roughly one-third of patients who do not respond to adequate trials of dopamine (DA)-blocking antipsychotics. About half of these also fail clozapine, leading to especially poor outcomes. TRS often appears early—most cases are resistant from first episode—though a minority convert to resistance later, potentially via relapse-related mechanisms. Predictors include younger onset, longer untreated psychosis, prominent negative symptoms, cognitive impairment, poorer premorbid function, obstetric complications, neurological soft signs, and higher familial risk. Converging biology suggests TRS differs from treatment-responsive illness: normal striatal DA synthesis capacity with elevated anterior cingulate glutamate, greater cortical thinning/atrophy and dysconnectivity (notably prefrontal/frontotemporal), and hints of distinct genetic burden.
Clozapine remains the gold standard and should be initiated earlier, yet is underused and delayed, with “ultra-TRS” common. Pharmacologic augmentation shows limited benefit and more side effects, though ECT can aid short-term outcomes and repetitive trans-magnetic stimulation and transcranial direct stimulation may help specific symptoms. Given the likely glutamatergic/GABAergic and endocannabinoid involvement, novel targets are promising. Clinically, the field needs reliable biomarkers and simple predictive tools to identify DA-nonresponders early and triage to clozapine or alternatives, alongside standardized definitions and multicenter validations to stratify patients and personalize therapy.
Reference: Leung CC, Gadelrab R, Ntephe CU, McGuire PK, Demjaha A. Clinical Course, Neurobiology and Therapeutic Approaches to Treatment Resistant Schizophrenia. Toward an Integrated View. Front Psychiatry. 2019;10:601. doi: 10.3389/fpsyt.2019.00601.
Josh Hamilton
DNP, APRN-BC, CTMH, CNE, CLNC, FAANP