Objective: The study objective was to examine whether and when antipsychotic-induced weight gain in first episode psychosis (FEP) stabilizes over a 12-month exposure to the same antipsychotic in a sample of previously untreated FEP patients.
Methods: In this prospective naturalistic outcome study, 109 patients diagnosed with non-affective or affective psychosis (DSM-IV) were treated with the same antipsychotic medication (olanzapine n = 45, risperidone n = 39, or aripiprazole n = 25) throughout the first year of treatment. Body weight was measured and body mass index calculated at baseline and 1, 2, 3, 6, 9, and 12 months. Additional weight data over the second year were available, making extending the comparison for a second year possible.
Results: Linear mixed model analysis showed a significant main effect of time (Type III test P < .001) after adjusting for baseline weight values. Post hoc pairwise comparisons showed that incremental weight changes subsequent to month 6 were insignificant, suggesting weight stabilization by month 9. No significant difference (P = .243) between groups or time × group interaction (P = .111) was observed. Similar findings were obtained with BMI. A follow-up analysis, of a subsample who continued treatment with the same antipsychotic for an additional 12 months (n = 57), confirmed weight stabilization in the second year. There was no significant main effect of time (P = .641), group (P = .539), or time × group interaction (P = .250).
Conclusions: Antipsychotic-induced weight gain occurs mostly in the first few months of treatment. Preventive interventions concurrent to second-generation antipsychotic treatment initiation in medication-naive FEP patients might be warranted.
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