More severe substantia nigra neuronal loss in PD than in DLB; higher burden of cortical Lewy bodies in temporal and parietal cortex, more frequent and severe alpha‐synuclein load in the CA2 region of the hippocampus, and higher beta‐amyloid load in cortical and subcortical regions in DLB than in PD. This evidence concerns the gene SNCA and Lewy body dementia.