We would like to highlight an important technical limitation that should be considered before accepting these results as conclusive. Sheline et al. observed an average hippocampal volume of 8,298.2 mm3 in the group of patients who achieved remission from depression and 7,942.3 mm3 in those who did not achieve remission after treatment. The values are provided in volume (mm3), and although the volumetric difference seems large, the difference represents less than 0.3 mm on each dimension of the measured volume. The cubic root of 8,298.2 mm3 is 20.24 mm and the cubic root of 7,942.3 mm3 is 19.95 mm, so the approximate difference in each dimension measured of the volume of hippocampus is in the range of 0.3 mm, which is below the resolution of MRI.