Dimethylguanidino-valeric acid, a metabolite associated with impaired fatty acid and amino acid metabolism, showed a stronger positive association with dementia risk among individuals carrying the C allele at rs2154481, a variant mapped to the APP gene that encodes Aβ precursor protein (APP), suggesting that dysregulated lipid and glucose metabolism may influence the processing of APP, leading to increased Aβ production34. This evidence concerns the gene APP and dementia.