Impaired functioning in euthymic patients with bipolar disorder--HSV-1 as a predictor.

There is a possible association between infectious agents and psychiatric disorders. Previous studies in the US provided evidence for cognitive impairment correlated with Herpes simplex virus type 1 (HSV-1) infection. For a replication study in Europe we chosed individuals diagnosed with bipolar disorder to analyse the correlation with HSV-1 infection. Antibody prevalence was analyzed by using solid phase immunoassay techniques. Cognitive functioning was tested with the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) Form A, the Trail Making Test A&B, and two subtests from the WAIS III: the Letter Number Sequencing Task and the subtest on information. History and psychopathology was assessed using structured interviews and validated rating scales (SCID, HRSD-21, YMRS, PANSS). Additionally, we investigated social functioning and quality of life using self-assessment-scales (SAS, LQLP). Prevalence rates of antibodies against diverse infectious agents did not differ significantly between patients and controls. We found a significant correlation between cognitive impairment in patients with bipolar disorder and the prevalence of antibodies directed against HSV-1. Cognitive functions were significantly impaired including language, attention, and immediate memory. The results of this study confirm previous findings suggesting that HSV-1 affects cognitive functions in patients with bipolar disorder. This may also result in more impaired functioning, less quality of life and difficulties in social adjustment.