Abstract Importance The relationship between HRT use and dementia risk is unclear, with studies reporting both increased and decreased risk. Objective To identify modulators of the association between HRT use and dementia risk and identify potentially responsive subgroups of women. Design, setting, and participants This study used data from the UK Biobank, with baseline assessment conducted between 2006 and 2010 and follow up through to October 2022. The cohort included post-menopausal women without a diagnosis of…