The Association between Suicide Attempts and Toxoplasma gondii Infection

OBJECTIVE: Chronic ‘latent’ infection by Toxoplasma 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: One hundred fifty-five 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 17-item Korean version of Hamilton Depression Scale (HAMD), Columbia Suicide Severity Rating Scale (C-SSRS), State-Trait Anxiety Inventory (STAI) and Korean-Barratt Impulsiveness Scale (BIS). RESULTS: Immunoglobulin G 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.

The Normalization of Brain ¹⁸F-fluorodeoxy-D-glucose Positron Emission Tomography Hypometabolism following Electroconvulsive Therapy in a 55-year-old Woman with Treatment-resistant Late Onset Depression: A Case Report

Major depressive disorder, especially in later life, has heterogeneous clinical characteristics and treatment responses. Symptomatically, psychomotor retardation, lack of energy, and apathy tends to be more common in people with late-onset depression (LOD). Despite recent advances in psychopharmacologic treatments, 20% to 30% of patients with mood disorders experience inadequate responses to medication, often resulting in a trial of electroconvulsive therapy (ECT). However, the therapeutic mechanism of ECT is still unclear. By using ¹⁸F-fluorodeoxy-D-glucose positron emission tomography-computed tomography (18F-FDG PET/CT), we can obtain the status of brain metabolism in patients with neuropsychiatric disorders and changes during psychiatric treatment course. The object of this case report is evaluating the effect of ECT on brain metabolism in treatment-refractory LOD by PET/CT and understanding the mode of action of ECT. In this case report, we presented a 55-year-old female patient who suffered psychotic depression that was resistant to pharmacological treatment. Several antidepressants and atypical anti-psychotics were applied but there was no improvement in her symptoms. The patient presented not only depressed mood and behaviors but also deficit in cognitive functions. We found decreased diffuse cerebral metabolism in her brain ¹⁸F-FDG PET/CT image. ECT resulted in amelioration of the patients' symptoms and another brain PET imaging 7 weeks after the last ECT course showed that her brain metabolism was normalized.