Parkinson's disease dementia (PDD) and dementia with Lewy bodies (DLB), collectively known as LBD, are synucleinopathies morphologically characterized by neuronal loss, inclusions containing Lewy body/α-synuclein and β-amyloid, and tau pathologies, often reported as part of the same spectrum (2, 3). This evidence concerns the gene SNCA and dementia.