Gray Matter Volumes and Treatment Response of Psychotic Symptoms to Risperidone in Antipsychotic-Naive Alzheimer's Disease Patients

Objective: The purpose of this study was to determine whether gray matter volumes are associated with treatment response of psychotic symptoms in Alzheimer's disease (AD) patients. Method: Risperidone, which is commonly used as an atypical antipsychotic drug, was administered in a clinical setting for 6 weeks from April 2012 to February 2013 to 25 antipsychotic-naive AD patients with psychosis, diagnosed according to Jeste and Finkel's proposed diagnostic criteria for psychosis of Alzheimer's disease. Psychotic symptoms were rated with the Korean version of the Neuropsychiatric Inventory (K-NPI) at baseline and at 6 weeks, and treatment response was defined as the change in K-NPI score from baseline to 6 weeks. Gray matter volumes were measured with magnetic resonance imaging and voxel-based morphometry at baseline. Age, gender, years of education, total intracranial volume, apolipoprotein E genotype, dosage of risperidone, the baseline scores on the Korean version of the Mini-Mental State Examination, and the baseline psychotic and nonpsychotic symptoms scores on the K-NPI were measured as covariates of no interest. Results: We found that treatment response of psychotic symptoms to risperidone in antipsychotic-naive AD patients was positively associated with both left and right putamina, left parahippocampal gyrus, and left amygdala volume after controlling covariates of no interest (uncorrected P < .001, K-E > 100 voxels). Conclusions: Therefore, we conclude that gray matter volumes of putamina, left parahippocampal gyrus, and left amygdala are associated with treatment response of psychotic symptoms after 6 weeks of treatment with risperidone in antipsychotic-naive AD patients with psychosis. These results suggest that the volumes of specific gray matter regions probably contribute to treatment response of psychotic symptoms in AD patients.