Exploratory analysis of the whole hippocampus showed that the polymorphism did not moderate the effect of PTSD symptoms on the volume of the entire left (ΔF = 0.47, p = 0.624, ΔR2 = 0.004) or right (ΔF = 0.24, p = 0.786, ΔR2 = 0.002) hippocampus, suggesting that subfield volumes are more sensitive to DRD2 Taq1A polymorphism moderation when exposed to stress. This evidence concerns the gene DRD2 and post-traumatic stress disorder.