The Course of Relapse Following Antipsychotic Discontinuation in Schizophrenia: A Test of the Antipsychotic Withdrawal Syndrome Hypothesis of Relapse

Abstract Background Antipsychotics are central to relapse prevention in schizophrenia, but longer-term use is associated with adverse effects that often prompt dose reduction or discontinuation. Although relapse risk increases after discontinuation, the nature of relapse remains unclear. Specifically, it is uncertain whether relapse reflects re-emergence of underlying illness or pharmacological withdrawal. Methods We analysed longitudinal symptom data (Positive and Negative Syndrome Scale; PANSS) from 417 individuals with schizophrenia who experienced relapse post-stabilization in five randomized, double-blind, placebo-controlled discontinuation trials of oral and long-acting injectable (LAI) paliperidone. Latent class mixed modelling was used to identify distinct trajectories of symptom change preceding relapse. Findings Two latent classes of relapse were identified: ‘rapid’ and ‘delayed’ onset. Rapid relapse was associated with more severe positive, negative, and cognitive symptoms at relapse. The proportion of individuals experiencing rapid relapse did not differ between those randomized to placebo (treatment discontinuation) versus treatment continuation in either LAI (p=0.119) or oral trials (p=0.949). No consistent increase in withdrawal-like symptoms (e.g. anxiety, agitation, depression) was found in discontinuation compared to continuation groups. Across formulations, individuals with rapid relapse had significantly higher baseline PANSS scores than those with delayed relapse (p