The study's findings, reported in the Sept. 6 issue of The Lancet, trace the disorders to reduced expression of the genes, known as oligodendrocytes, responsible for myelin development in brain cells. Composed mostly of fats and proteins, myelin sheaths insulate nerve cells, enabling them to safely conduct electric signals between the brain and other parts of the body.
"Patients with schizophrenia and bipolar disorder differ in terms of their presentation and clinical course," says the study's co-author, Robert Yolken, M.D., a neurovirologist at the Children's Center.
"However, there is some overlap in terms of symptoms and there are medications that have been used for the treatment of both disorders. Our findings suggest that there are similar mechanisms involved in both disorders and that they may be more closely related than previously thought."
In the study, researchers compared expression of myelin-associated genes in the preserved brains of 15 people with schizophrenia, 15 with manic-depressive illness (bipolar disorder), and 15 from a control group of individuals with neither disorder.
"The expression profiles of most known oligodendrocyte-specific and myelin-associated genes were greatly reduced, and several transcription factors known to coordinate myelin gene expression showed corresponding changes," says Yolken. "These results provide strong evidence for oligodendrocyte and myelin dysfunction in patients with schizophrenia and bipolar disorder."
Yolken says the reason for this dysfunction is not currently known, but may be related, in some cases, to infections of the central nervous system or other env
Contact: Jessica Collins
Johns Hopkins Medical Institutions