Bipolar disorder is the least Studied among the three major psychiatric disorders of schizophrenia, major depression and bipolar disorder. Furthermore, investigations on infection and immunity in bipolar disorder make up only a small portion of the sparse research done on this disorder. However, there are reports that modulation of the immune system and certain infections might be associated with bipolar disorder and that there might be differences between bipolar and the other disorders. The purpose of this paper is to briefly review published data on these issues in bipolar versus the other disorders, and to present an ongoing clinical study on the putative involvement of infection with the parasite Toxoplasma gondii in these three major psychiatric disorders.
We studied a Japanese patient who developed parkinsonian symptoms over 3 months before the diagnosis of acquired immunodeficiency syndrome. Brain MRI showed multiple lesions with mass effect and ring enhancement in the basal ganglia and subcortical white matter suggesting Toxoplasma infection. Anti-Toxoplasma therapy and highly active antiretroviral therapy for 6 months allowed improvement of parkinsonism, brain MRI findings, and immune system.