Herpes is the dreaded ‘gift that keeps on giving’. But could it also be taking our memories? Decades of research show a striking correlation between Alzheimer’s disease risk and infection with Herpes Simplex Virus 1 (HSV1) in people carrying a specific gene. Now, newly-available epidemiological data provide a causal link between HSV1 infection and senile dementia — raising the tantalizing prospect of a simple, effective preventive treatment for one of humanity’s costliest disorders.