Association of serum antibodies to herpes simplex virus 1 with cognitive deficits in individuals with schizophrenia

Background: Cognitive deficits are a characteristic feature of schizophrenia and contribute to the profound disabilities associated with this illness. Some of the cognitive deficits that occur in individuals with schizophrenia are similar to those found in individuals who have recovered from central nervous system infections with human herpesviruses. Methods: We measured cognitive functioning and serologic evidence of infection with human herpesviruses in 229 outpatients with schizophrenia. We evaluated cognitive functioning with the Repeatable Battery for the Assessment of Neuropsychological Status. For each patient, serum IgG class antibodies with specificities for the following potentially neurotropic human herpesviruses were measured by means of a solid-phase immunoassay: herpes simplex viruses 1 and 2, cytomegalovirus, Epstein-Barr virus, human herpesvirus 6, and varicellazoster virus. We determined the association between serologic evidence of herpesviruses infection and cognitive functioning by univariate and multivariate analyses, including demographic and clinical factors associated with cognitive functioning. Results: We found that serologic evidence of infection with herpes simplex virus 1 is an independent predictor of cognitive dysfunction in individuals with schizophrenia. Discriminant function analysis indicated that much of the difference in cognitive functioning could be attributed to immediate memory. We found no significant association between cognitive dysfunction and serologic evidence of infection with other human herpesviruses. Conclusion: Serologic evidence of herpes simplex virus 1 infection is associated with cognitive impairment in schizophrenia.