Voxel-based morphometry has been used to investigate the associations between regional gray and white matter volume and cognitive function. The manuscript introduces these studies' methods, cautions, results, and problems related to the reports of the results. In many studies of ours that investigating these associations using the huge sample size and robust statistics, the associations were weak and wide spread in the brain. These patterns of results suggest the difficulty in finding the specific neural bases that underlie individual cognitive functions through VBM.