Voxel-based morphometry in Alzheimer's disease

Recent morphometric MRI studies have investigated brain volume abnormalities associated with the diagnosis of Alzheimer's disease (AD) using voxel-based morphometry (VBM). This technique allows the assessment of gray matter volumes in subjects with AD or related conditions compared with healthy controls in an automated fashion, across the whole brain. This article reviews VBM findings related to different AD stages and its prodrome, mild cognitive impairment. These findings include not only gray matter deficits in medial temporal structures as seen in former MRI studies of AD conducted using manual region-of-interest measurements, but also volume changes in several other brain regions not assessed in previous MRI studies. We also discuss potential applications of VBM to improve AD diagnostic accuracy in routine clinical practice. Finally, we highlight future research directions in this field, including: investigations on the relationship between VBM findings of multifocal gray matter deficits and changes in white matter tracts that interconnect such regions; the need for population-based VBM studies using large AD samples; and the potential of studies combining VBM measurements with other potential biological markers (such as brain imaging indices of amyloid-beta deposition and cerebrospinal fluid AD markers) to further advance our knowledge about the physiopathology of AD.