Interaction between baseline BMI and baseline disease severity predicts greater improvement in negative symptoms in first-episode schizophrenia

Several studies have reported that baseline symptom severity in patients with schizophrenia (SCZ) is associated with the efficacy of antipsychotic medication. Overweight/obesity is common in SCZ and has also been reported to be correlated with therapeutic response to antipsychotics. This study aimed to evaluate whether baseline body mass index (BMI) and disease severity were associated with improvements in negative symptoms in patients with first-episode and medication-naive (FEMN) SCZ. A total of 241 FEMN patients were recruited in this study and treated with oral risperidone over 3 months. Clinical symptoms were measured by the Positive and Negative Syndrome Scale (PANSS) and BMI was assessed at baseline and 3-month follow-up. We found that baseline BMI was correlated with the baseline severity of symptoms. Baseline BMI or baseline disease severity was associated with improvement in negative symptoms after 3 months of treatment. Linear regression analysis indicated that the interaction of BMI and disease severity at baseline was associated with improvement in negative symptoms in the early stage of SCZ after controlling for sex, age, and dose of risperidone. Our study suggests that the interaction of baseline BMI and disease severity may play a role in predicting negative symptom improvement after 3 months of risperidone treatment.