SNCA and Alzheimer disease: The distinct topographies of Lewy body pathology match the presenting clinical features of DLB and PD: In DLB, early cognitive and neuropsychiatric impairments, with or without motor decline, on the basis of cortical and limbic alpha-synuclein pathology, and frequently in association with some degree of concurrent Alzheimer’s disease (AD) neuropathologic change(31–35); in PD, largely isolated motor manifestations of parkinsonism on the basis of alpha-synuclein pathology and dopamine cell loss in the substantia nigra pars compacta.