HSV Type 1 and bipolar disorder

Serologic evidence of herpes simplex virus type 1 infection is associated with cognitive impairment in individuals with bipolar disorder.

Dickerson, F.B. (2004). Infection with herpes simplex virus type 1 is associated with cognitive deficits in bipolar disorder. Biol Psychiatry, 55. Retrieved from https://www.ncbi.nlm.nih.gov/m/pubmed/15013827/

Herpes viruses cause a spectrum of pathology in the human brain, ranging from apparently asymptomatic latent infection to catastrophic encephalitis. A growing body of evidence suggests that individuals exposed chronically to herpes viruses, particularly HSV1 have impaired cognitive performance compared with unexposed individuals. The differences are detectable among otherwise healthy individuals; they are more substantial among persons with schizophrenia. Similar associations have also been observed among patients with bipolar disorder, suggesting that the HSV1 associations may not be restricted to a particular psychiatric diagnostic group.

Prasad, K.M., & Watson, A.M. (2012). Exposure to Herpes Simplex Virus Type 1 and Cognitive Impairments in Individuals With Schizophrenia. Schizophr Bull, 38. Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3494052/