One hundred and seventy-five participants (N=70 HSV-1 seropositive and N=105 HSV-1 seronegative) will be randomized 1:1 to receive adjunctive valacyclovir or adjunctive placebo for a 16 week period. The primary outcome that will be assessed is improvement in changes in visual and working memory scores in HSV-1 positive and negative participants over the course of the study. We will also measure the overall cognitive functioning and the severity of psychiatric symptoms over the course of the study and will evaluate the tolerability and safety of valacyclovir treatment in this population. In addition, we will explore the relationship between changes in the levels of inflammatory markers (HSV2, CMV, EBV, CRP, and Toxoplasmosis) and treatment response over the course of the study.