Hormone replacement therapy (HRT) may help prevent Alzheimer’s disease, new research suggested. Previous research found APOE4 to be a significant risk factor gene for Alzheimer’s disease, although inheriting the gene does not mean that someone will definitely develop the condition. In this latest study, published in the journal Alzheimer’s Research & Therapy, the team found that HRT was most effective when given during perimenopause, where symptoms build up months or years before periods actually stop.