The current pilot immunohistochemistry screen assessed human post-mortem brain tissue from Parkinson’s disease (PD) at Braak stages 4–6 and incidental Lewy body disease (ILBD; representative of pre-clinical PD [27]), highlighting elevated protein levels of specific PAD isozymes and increased deimination and histone H3 deimination in early stages of PD. This evidence concerns the gene PADI4 and Lewy body dementia.