SNCA and Parkinson disease: SV2A density was decreased by 5% in PD (p = 0.006), and 6% in PDD (p < 0.001), and did not differ in DLB (p = 0.105) compared to controls across all regions (Fig. 3B). When looking at regions affected at different Braak α-synuclein stages, SV2A density was significantly lower in regions affected at Braak 4 in DLB (-10%, p = 0.001) and PDD (-10%, p < 0.001) compared to controls, and in regions affected at Braak 5 in PD (-10%, p < 0.001), PDD (-7%, p = 0.003) and DLB (-6%, p = 0.047) compared to controls (Fig. 3D, F). SV2A density did not differ between groups in regions affected at Braak 6.