Exposure to herpes simplex virus, type 1 and reduced cognitive function

Abstract

Herpes Simplex virus, type 1 (HSV-1) causes cold sores, keratitis and rarely, fatal encephalitis. The infection is life long, with sensory ganglia serving as reservoirs of latent infection. Recently, exposure to HSV-1 has also been repeatedly associated with reduced cognitive function among healthy individuals without prior encephalitis. Though HSV-1 does not elevate risk for schizophrenia (SZ) per se, exposure is likewise associated with impaired cognitive functions among SZ patients. The range of cognitive changes observed in HSV-1 exposed persons has not been investigated systematically, nor is it known whether interaction between HSV-1 exposure and SZ related factors contributes to the impairment among SZ patients. Persons with or without schizophrenia/schizophreniform disorder (N = 298 total, DSM IV criteria) were assessed for HSV-1 exposure using serum HSV-1 antibody titers. The Penn Computerized Neurocognitive battery was used to assess eight cognitive domains with respect to accuracy and speed. There were no significant case-control differences in HSV-1 exposure. The SZ/schizophreniform disorder cases were significantly impaired in all cognitive domains compared with the controls. HSV-1 exposure was also associated with reduced cognitive function in the entire sample, but the magnitude of the effects and their patterns differed from the SZ related changes. Further, statistically significant interactions between HSV-1 exposure and SZ case status were not detected. HSV-1 exposure does not elevate risk for SZ, but it is associated with reduced function in specific cognitive domains regardless of SZ diagnostic status. An ‘epidiagnostic’ model for the association is proposed to explain the results.

A randomised controlled trial of adjunctive yoga and adjunctive physical exercise training for cognitive dysfunction in schizophrenia

“…Two block randomised lists were prepared in advance to enable age stratified randomisation: 18–30 years or older than 30 years. The age range was based on the mean age of SZ participants enrolled in our prior research studies (33,34). The randomisation lists were stored in a password-protected computer by TB, who did not collect outcome measures, administer any interventions or treat the participants.…”

Different presence of Chlamydia pneumoniae, herpes simplex virus type 1, human herpes virus 6, and Toxoplasma gondii in schizophrenia: meta-analysis and analytical study

“… 26 , 53 Moreover, a controlled trial showed an improvement in cognitive functioning among seropositive schizophrenic patients treated with one antipsychotic plus valacyclovir when compared to those treated with the antipsychotic agent only. 54 Nevertheless, these results may be due to a simple clinical coincidence 30 due to the high prevalence of this infection, as shown in other studies ( Table 2 ). Also, regarding the possible role of the glutamate system, the association between mutations in the specific GluN2B N-methyl-D-aspartate (NMDA) receptor subunit and maternal herpes simplex virus infection and schizophrenia, 55 a disorder where brain activation and cortical neurotoxicity of NMDA receptor antagonists, has been extensively reported.…”

Natural cause mortality in persons with serious mental illness

“…The current study also builds on our studies in that previously we have found an association between exposure to other human herpes viruses and clinical characteristics in serious mental illness. Specifically, we have demonstrated a robust association between exposure to human simplex virus type 1 (HSV‐1) and reduced cognitive functioning in schizophrenia and bipolar disorder . In an earlier study with a small version of our mortality cohort limited to schizophrenia, we also found an association between HSV‐1 antibody levels and natural cause mortality ; however, this association is not apparent in this larger cohort.…”