Changes in White Blood Cell and Neutrophil Counts in Patients With Schizophrenia Treated With Lithium Carbonate, Adenine, and Ninjin‐Yoei‐To: A Preliminary Study

Aim Clozapine is often unavailable to patients with treatment‐resistant schizophrenia when white blood cell (WBC) and neutrophil counts do not meet the required thresholds. This study aimed to examine changes in WBC and neutrophil counts and the factors associated with these changes. Methods Thirty‐five patients with schizophrenia who received adenine, Ninjin‐yoei‐to, or lithium carbonate were included in the treatment group. Eighty‐one patients with schizophrenia comprised the control group. A two‐way mixed analysis of variance (ANOVA) was used to compare changes in WBC and neutrophil counts before and after treatment. Stepwise multiple regression analyses were conducted to identify factors associated with changes in WBC and neutrophil counts. Results In the two‐way mixed ANOVA, WBC and neutrophil counts in the treatment group were significantly lower than those in the control group at baseline ( p < 0.001), and the counts at the final examination were significantly higher than the baseline values in the treatment group ( p < 0.001). Stepwise multiple regression analyses revealed that adenine and lithium carbonate were significant predictors of changes in WBC (adjusted R 2 = 0.173, p < 0.001) and neutrophil counts (adjusted R 2 = 0.175, p < 0.001). Conclusion Lithium carbonate and adenine may help increase the WBC and neutrophil counts in patients with schizophrenia. These agents may be useful for patients with low WBC and neutrophil counts prior to initiating clozapine treatment.