Association of Temporolimbic Volumes with Treatment Response to Antipsychotic Medication for Delusion in Patients with Alzheimer’s Disease

OBJECTIVE: This study investigated the association between gray matter volume and the treatment response to antipsychotic medication in patients with Alzheimer’s disease (AD). METHODS: We included 26 AD patients with delusions from the Memory Impairment Center of the Pusan National University Hospital in South Korea. All participants underwent baseline brain magnetic resonance imaging and took risperidone as an antipsychotic medication for 6 weeks. Gray matter volumes were measured using voxel-based morphometry at baseline. Treatment response with respect to delusional symptoms was defined as the change in delusion item scores in the Korean version of the Neuropsychiatry Inventory (K-NPI), from baseline to 6 weeks later. A voxel-based multiple linear regression model integrated with statistical parametric mapping was used to investigate the association between gray matter volume and treatment response after controlling for covariates. RESULTS: The treatment response was significantly positively correlated with gray matter volume in the temporal lobe (both the fusiform gyri and the left superior and inferior temporal gyri) and the limbic system (the left parahippocampal gyrus and left amygdala) after controlling for age, sex, education level, total intracranial volume, risperidone dosage, baseline Korean version of the Mini-Mental Status Examination scores, and baseline K-NPI scores for the delusion and non-delusion domains (P < .001, uncorrected, K(E) > 100 voxels). CONCLUSION: Our findings suggest that specific gray matter volumes, including those of the temporal region and the limbic system, may affect treatment response to antipsychotic medication in terms of delusional symptoms in patients with AD.