Antipsychotic response in the first week predicts later efficacy
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Updated: May 20, 2026

Behavioral Characterization of Pentylenetetrazole-induced Seizures: Moving Beyond the Racine Scale
Published on: July 8, 2025
Ina Giegling1, Stefano Porcelli, Beatrice Balzarro
1Department of Psychiatry, Ludwig Maximilians University, Munich, Germany.
Background And Aims:
Time of onset of antipsychotic action is still a debated matter. We aimed to replicate and extend previous findings that early response can predict subsequent non-response.
Methods:
86 acutely psychotic patients treated with haloperidol were studied.
Results:
A PANSS reduction ≤16% at 1 week predicts non-response at 3 weeks of treatment (specificity 92%, sensitivity 82%). Conversely, a PANSS reduction ≥23% at 1 week of treatment predicts response at 3 weeks, with a specificity of 84% and a sensitivity of 86%.
Conclusion:
Our results confirm that an early response to antipsychotic treatment accurately predicts the treatment effectiveness and extends it to a prediction performed as early as 1 week.
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