<jats:sec><jats:title>Objective</jats:title><jats:p>We conducted a neuroimaging analysis to understand the neuroanatomical correlates of gray matter loss in a group of mild cognitive impairment and early Alzheimer's disease patients who developed delusions.</jats:p></jats:sec><jats:sec><jats:title>Methods</jats:title><jats:p>With data collected as part of the Alzheimer's Disease Neuroimaging Initiative, we conducted voxel‐based morphometry to determine areas of gray matter change in the same Alzheimer's Disease Neuroimaging Initiative participants, before and after they developed delusions.</jats:p></jats:sec><jats:sec><jats:title>Results</jats:title><jats:p>We identified 14 voxel clusters with significant gray matter decrease in patient scans post‐delusional onset, correcting for multiple comparisons (false discovery rate, <jats:italic>p</jats:italic> < 0.05). Major areas of difference included the right and left insulae, left precuneus, the right and left cerebellar culmen, the left superior temporal gyrus, the right posterior cingulate, the right thalamus, and the left parahippocampal gyrus.</jats:p></jats:sec><jats:sec><jats:title>Conclusions</jats:title><jats:p>Although contrary to our initial predictions of enhanced right frontal atrophy, our preliminary work identifies several neuroanatomical areas, including the cerebellum and left posterior hemisphere, which may be involved in delusional development in these patients. Copyright © 2015 John Wiley & Sons, Ltd.</jats:p></jats:sec>