The Association between Suicide Attempts and Toxoplasma gondii Infection
Jeongjae Bak 1, Se-Hoon Shim 1*, Young-Joon Kwon 1, Hwa-Young Lee 1, Ji-Sun Kim 1, Heejung Yoon 2, Yeon-Jung Lee 3
1Department of Psychiatry, Soonchunhyang University Cheonan Hospital, College of Medicine, Soonchunhyang University, Cheonan, Korea., 2Korean Society of Infectious Diseases, 3Department of Psychiatry, Soonchunhyang University Seoul Hospital
Received: May 6, 2017; Revised: July 5, 2017; Accepted: July 28, 2017; Published online: July 28, 2017.
© The Korean College of Neuropsychopharmacology. All rights reserved.

Background/Objective: Chronic ‘latent’ infection by Toxoplasma gondii (T. gondii) is common and most of the hosts have minimal symptoms or they are even asymptomatic. However, there are possible mechanisms by which T. gondii may affect human behavior and it may also cause humans to attempt suicide. This article aimed to investigate the potential pathophysiological relationship between suicide attempts and T. gondii infection in Korea.
Methods: 155 psychiatric patients with a history of suicide attempt and 135 healthy control individuals were examined with enzyme-linked immunoassays and fluorescent antibody technique for T. gondii seropositivity and antibody titers. The group of suicide attempters was interviewed regarding the history of suicide attempt during lifetime and evaluated using HAMD, C-SSRS, STAI and BIS.
Results: IgG antibodies were found in 21 of the 155 suicide attempters and in 8 of the 135 controls (p = 0.011). The Toxoplasma-seropositive suicide attempters had a higher HAMD score on the depressed mood and feeling of guilt subscales and a higher total score than the seronegative suicide attempters. T. gondii seropositive status was associated with higher C-SSRS in the severity and lethality subscales. T. gondii IgG seropositivity was significantly associated with higher STAI-X1 scores in the suicide attempters group.
Conclusion: Suicide attempters showed higher seroprevalence of T. gondii than healthy controls. Among the suicide attempters, the T. gondii seropositive and seronegative groups showed several differences in the aspects of suicide. These results suggested a significant association between T. gondii infection and psychiatric problems in suicidality.
Keywords: Suicide, Toxoplasma, Infection, Depression, Anxiety, Impulse control