Exposure to herpes simplex virus type 1 and cognitive impairments in individuals with schizophrenia

Konasale M. Prasad, Annie M.M. Watson, Faith B. Dickerson, Robert H. Yolken, Vishwajit L. Nimgaonkar

Research output: Contribution to journalArticlepeer-review

Abstract

Latent infection with neurotropic herpes viruses, such as herpes simplex virus, type 1 (HSV1), has been generally considered benign in most immunocompetent individuals except for rare cases of encephalitis. However, several recent studies have shown impaired cognitive functions among individuals with schizophrenia exposed to HSV1 compared with schizophrenia patients not exposed to HSV1. Such impairments are robust and are prominently observed in working memory, verbal memory, and executive functions. Brain regions that play a key role in the regulation of these domains have shown smaller volumes, along with correlation between these morphometric changes and cognitive impairments in schizophrenia. One study noted temporal decline in executive function and gray matter loss among HSV1-exposed first-episode antipsychotic-naïve schizophrenia patients. Furthermore, a proof-of-concept double-blind placebo-controlled trial indicated improvement in cognitive performance following supplemental anti-herpes-specific medication among HSV1 seropositive schizophrenia patients. Cross-sectional studies have also identified an association between HSV1 exposure and lesser degrees of cognitive impairment among healthy control individuals and patients with bipolar disorder. These studies fulfill several Bradford-Hill criteria, suggesting etiological links between HSV1 exposure and cognitive impairment. Exposure to other human herpes viruses such as cytomegalovirus and herpes simplex virus type 2 (HSV2) may also be associated with cognitive impairment, but the data are less consistent. These studies are reviewed critically and further lines of enquiry recommended. The results are important from a public health perspective, as HSV1 exposure is highly prevalent in many populations.

Original languageEnglish (US)
Pages (from-to)1137-1148
Number of pages12
JournalSchizophrenia bulletin
Volume38
Issue number6
DOIs
StatePublished - Nov 2012

Keywords

  • HSV1
  • cognition
  • herpes
  • neuroimaging
  • neuroscience
  • schizophrenia

ASJC Scopus subject areas

  • Psychiatry and Mental health

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