Immunity, Infection and Suicidal Behavior

Immunity, Infection and Suicidal Behavior

Teodor Postolache, M.D.

Teodor Postolache, M.D., has received two AFSP grants, a Pilot Research Grant in 2004 and a Standard Research Grant in 2009. Both of these studies examined the relationship between the response of the brain to infection and suicidal behavior. Genetics plays a role in how the body responds to infection, and the immune response has been shown to affect mood and behavior in many studies. By studying common immune factors, Dr. Postolache is testing the interaction between genetic and environmental factors that may contribute to suicidal behavior. Ultimately his hope is that we can develop interventions that help prevent suicide.

In his first AFSP grant, Dr. Postolache compared the brains of 34 people who died by suicide and 17 who died by other causes. He studied brain gene expression of cytokines, the immune system molecules that signal between cells to organize the defense against infection, cancer and transplanted organs. He demonstrated that cytokine gene expression was greater in the orbitofrontal cortex of the brains of people who died by suicide than in controls. The orbitofrontal cortex has been shown to be involved in aggression, impulsivity and suicidal behavior. The specific cytokines that were increased were different for men and women. Overall, the study findings suggested an association between the a brain immune response and suicide and led to Dr. Postolache’s $1,189,000 grant from the National Institutes of Health on immune triggers of suicidal behavior, a collaboration with Danish investigators.

In his next AFSP study, Dr. Postolache studied the presence of a parasite that infects the brain, Toxoplasma gondii (T. gondii), in people with schizophrenia. Previously, he had found that T. gondii was more likely to be found in people with mood disorders who had made a suicide attempt than people with mood disorders who had never attempted suicide. He replicated that finding in a sample of people with schizophrenia from Germany, which supports a role of infection and the response to infection in suicide attempts. The specific roles that infection and inflammation play in suicide attempts and suicide are not clear and further research that studies people over time may tell us more about these potentially modifiable risk factors.  Of major importance will be to investigate interactions between infection and other individual vulnerabilities and resiliencies, considering that only a small proportion of T. gondii infected individuals attempt suicide.  

According to the Centers for Disease Control and Prevention, more than 60 million men, women and children in the U.S. carry the T. gondii  parasite, but very few have symptoms because the immune system usually keeps the parasite from causing illness. Toxoplasmosis is considered one of the neglected parasitic infections, a group of five parasitic diseases that have been targeted by CDC for public health action.”

Teodor Postolache, M.D., is an Associate Professor of Psychiatry and the Director of the Mood and Anxiety Program at the University of Maryland. Click here to read more about Dr. Postolache's Standard Research Grant.

Published articles from this study:

  • Ling, V. J., Lester, D., Mortensen, P. B., Langenberg, P. W., & Postolache, T. T. (2011). Toxoplasma gondii seropositivity and suicide rates in women. [Research Support, N.I.H., Extramural Research Support, Non-U.S. Gov't]. Journal of Nervous & Mental Disease, 199(7), 440-444.
  • Manalai, P., Hamilton, R. G., Langenberg, P., Kosisky, S. E., Lapidus, M., Sleemi, A., & Postolache, T. T. (2012). Pollen-specific immunoglobulin E positivity is associated with worsening of depression scores in bipolar disorder patients during high pollen season. Bipolar Disord, 14(1), 90-98. doi: 10.1111/j.1399-5618.2012.00983.x
  • Okusaga, O., Yolken, R. H., Langenberg, P., Lapidus, M., Arling, T. A., Dickerson, F. B., & Postolache, T. T. (2011). Association of seropositivity for influenza and coronaviruses with history of mood disorders and suicide attempts. [Research Support, N.I.H., Extramural  Research Support, Non-U.S. Gov't]. J Affect Disord, 130(1-2), 220-225.
  • Okusaga, O., Langenberg, P., Sleemi, A., Vaswani, D., Giegling, I., Hartmann, A.M., & Postolache, T.T.  (2012). Toxoplasma gondii antibody titers and history of suicide attempts in patients with schizophrenia. Schiz Res, 133: 150-155.
  • Pedersen Mg, M. P. N.-P. B. P. T. T. (2012). Toxoplasma gondii infection and self-directed violence in mothers. Arch Gen Psychiatry, 1-8. doi: 10.1001/archgenpsychiatry.2012.668
  • Sublette, M. E., Galfalvy, H. C., Fuchs, D., Lapidus, M., Grunebaum, M. F., Oquendo, M. A., & Postolache, T. T. (2011). Plasma kynurenine levels are elevated in suicide attempters with major depressive disorder. [Comparative Study Research Support, N.I.H., Extramural Research Support, Non-U.S. Gov't]. Brain, Behavior, & Immunity, 25(6), 1272-1278.
  • Tonelli, L.H., Stiller, J., Rujescu, D., Giegling, I., Schneider, B., Maurer, K., Schnabel, A., Möller, H-J., Chen, H.H., & Postolache, T.T. (2008).  Elevated cytokine expression in the orbitofrontal cortex of victims of suicide. Acta Psychiatr Scand, 117: 198-206.
  • Woo, J.-M., Okusaga, O., & Postolache, T. T. (2012). Seasonality of Suicidal Behavior. International Journal of Environmental Research and Public Health, 9(2), 531-547.