ObjectiveTo investigate the characteristics of gray matter structure and clinical symptoms in patients with Alzheimer's disease （AD） comorbid with apathy （AD-A）. MethodsThe study included 30 patients with AD-A， 30 AD disease patients without apathy （AD without apathy， AD-NA）， and 30 healthy controls （HCs） matched in gender， age， and years of education. All participants underwent a comprehensive neuropsychological assessment and magnetic resonance imaging （MRI） scans. Voxel-based morphometry （VBM） was used to analyze changes in gray matter volume among the three groups. Additionally， the correlation between the identified abnormal brain regions and apathy scale scores was analyzed. ResultsThere were no statistically significant differences among the three groups in terms of age， gender， years of education， or total intracranial volume. Compared with the HCs group， both the AD-A and AD-NA groups showed significantly lower scores in cognitive function （P<0.001）. The AD-A group exhibited significantly higher apathy scale scores compared with the AD-NA group （P<0.001）. Compared with the AD-NA group， the AD-A group showed reduced gray matter volume in the bilateral caudate nucleus， left orbitofrontal cortex， lingual gyrus， inferior frontal gyrus， superior frontal gyrus， entorhinal cortex， right middle frontal gyrus and posterior cingulate cortex （FWE-corrected， P<0.05 for all）. Compared with the HCs group， the AD-A group exhibited reduced gray matter volume in the bilateral middle temporal gyrus， left fusiform gyrus， calcarine sulcus， postcentral gyrus， right inferior frontal gyrus and supramarginal gyrus （FWE-corrected， P<0.05 for all）. Compared with the HCs group， the AD-NA group showed reduced gray matter volume in the left precuneus， inferior temporal gyrus， and right inferior temporal gyrus （FWE-corrected， P<0.05 for all）. In the AD-A group， changes in the gray matter volume of the left caudate nucleus （r= -0.557， P=0.002） and right middle frontal gyrus （r=-0.620， P=0.001） were negatively correlated with the apathy evaluation scale （AES） scores. ConclusionPatients in the AD-A group exhibited significant atrophy in the frontal-temporal-basal ganglia circuit， and the degree of gray matter atrophy was correlated with the severity of apathy.