The impact of Herpes simplex virus type 1 on cognitive impairments in young, healthy individuals - A historical prospective study

Compared to soldiers who were sero-negative, soldiers who were sero-positive for HSV had significantly lower IQ scores (IQ = 97.96, SD = 15.19 vs IQ = 103.23, SD = 14.23; p ≤ 0.001, effect size (ES) = 0.2), and significantly lower Hebrew language scores (ES = 0.1, p ≤ 0.01). The results remained significant after removing subjects with mild depression, anxiety or personality disorders. Although we could not control for socio-economic status directly, our findings indicate that infection with HSV-1 is associated with reduced cognitive functioning in healthy individuals. This finding adds to the growing number of studies in the schizophrenia literature and indicates that many research findings seemingly characteristic of schizophrenia are related to the association between HSV exposure and cognitive functioning in general, and are not illness specific.