SNCA and Lewy body dementia: We also found a SNP between MMRN1 and the 5′ end of SNCA, but not at the 3′ end to be significantly associated with lower odds of developing dementia, consistent with previous candidate gene studies13 and GWAS.11 Postmortem studies have found that alpha-synuclein in cortical areas is a predictor of dementia in Lewy body diseases.