Increased long-term antibody response to cytomegalovirus and decreased long-term antibody response to Toxoplasma gondii were associated with bipolar disorder as well as the subphenotypes of bipolar I, disease onset after age 19, and a history of manic psychosis.
The findings stem from a case-control study recently published online in JAMA Psychiatry.
“To our knowledge, this cohort of more than 1200 participants with bipolar disorder was the largest to be evaluated for environmental exposure to infection with quantification of immune activation and inflammation,” researchers wrote. “The sample size and clinical phenotyping of illness may provide potential new insights into pathophysiologic mechanisms warranting further study.”
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Researchers analyzed antibody titers from serum samples taken from 1207 patients with bipolar disorder and 745 control subjects to identify differences between the groups.
In addition to significantly higher cytomegalovirus immunoglobulin G (IgG) and significantly lower toxoplasma IgG in patients with bipolar disorder, the study revealed that the 272 patients with bipolar disorder who received drug treatment with antitoxoplasma activity had significantly lower Toxoplasma gondii immunoglobulin M (IgM) titers compared with the 900 patients who did not receive such treatment.
“Further work appears to be needed,” researchers wrote, “to better understand genetic vs environmental disease risk and infection or immune activation contribution to overall disease pathogenesis with particular reference to disease onset.”