We therefore aimed to investigate whether HSV‐1 seropositivity, indicating ever exposure to HSV‐1, or high IgG antibody titres and/or IgM antibodies, indicating recent HSV‐1 infection or reactivation, were associated with rates of cognitive decline or whole brain atrophy among individuals with and without PSEN1, PSEN2 and APP mutations from the Dominantly Inherited Alzheimer Network (DIAN) cohort. Here, CD40LG is linked to Mental deterioration.