Cytomegalovirus seropositivity and serointensity are associated with hippocampal volume and verbal memory in schizophrenia and bipolar disorder.

Cytomegalovirus (CMV) is a member of the herpesviridae family that
has a limbic and temporal gray matter tropism. It is usually latent in
humans but has been associated with schizophrenia, bipolar disorder and
cognitive deficits in some populations. Hippocampal decreased volume and
dysfunction play a critical role in these cognitive deficits. We
hypothesized that CMV seropositivity and serointensity would be
associated with hippocampal volume and cognitive functioning in patients
with schizophrenia or bipolar disorder.

METHODS:

102 healthy controls, 118 patients with bipolar disorder and 69 patients
with schizophrenia performed the California Verbal Learning Test (CVLT)
and had blood samples drawn to assess CMV IgG levels. A subgroup of 52
healthy controls, 31 patients with bipolar disorder and 27 patients with
schizophrenia underwent T1 MRI for hippocampal volumetry. We analyzed
the association between CMV serointensity and seropositivity with
hippocampal volume. We also explored the correlation between CMV
serointensity and seropositivity and CVLT scores.

RESULTS:

In both patient groups but not in controls, higher CMV serointensity was
significantly associated with smaller right hippocampal volume. Further,
in the group of patients with schizophrenia but not bipolar disorder,
CMV serointensity was negatively correlated with CVLT scores.

CONCLUSION:

CMV IgG titers are associated with decreased hippocampal volume and poorer
episodic verbal memory in patients with schizophrenia or bipolar
disorder. The mechanism of this association warrants further
exploration.