We observed a significant inverse association between global Aβ deposition and hippocampal SV2A binding in participants with aMCI (r = − 0.55, P = 0.04), but not mild dementia (r = 0.05, P = 0.82; difference statistically significant by Fisher z = − 1.80, P = 0.04). This evidence concerns the gene SV2A and dementia.