【 課題番号 3-2 】
Innovative Research Program on Suicide Countermeasures in FY2021: Report on Commissioned
Research Results

Field 3: Developing new policy areas
Topic number：3-2
Research topic:
Study on Enhancement and Improvement of Psychological Care/Support for People with Traumatic Experienceof Disaster and/or Child Abuse

Principal Researcher:
Yoshiharu Kim
Director General, National Institute of Mental Health, National Center of Neurology and Psychiatry

Co-Researcher:
Hiroaki Hori,Section Chief, Department of Behavioral Medicine, National Center of Neurology and Psychiatry

Summary:Childhood adversity, especially maltreatment, has been shown to increase the risk of developing psychiatricdisorders such as depression and posttraumatic stress disorder (PTSD), as well as the risk of suicide. Individuals
with a history of childhood maltreatment tend not to use help-seeking behaviors that can prevent suicidal
behaviors, and thus it is difficult to predict their suicidal behaviors. Therefore, it is important to develop
objective markers that can detect individuals with high suicide risk.
A growing number of studies have examined the biological basis of suicide, and evidence has suggested anassociation of suicide with inflammation and hypothalamic-pituitary-adrenal (HPA) axis function. However,such research is scarce on PTSD. Childhood maltreatment has been associated with alterations in theinflammatory system and HPA axis function and with increased suicide risk. To identify useful predictive
markers of suicide risk in patients with PTSD, the present study investigated the relationship of suicide risk with1

【 課題番号 3-2 】
blood levels of inflammatory molecules and HPA axis hormones, and further explored possible effects ofchildhood maltreatment.
A total of 93 civilian patients with PTSD and 119 healthy volunteers without traumatic experiences (allwomen, average age: late 30s) participated in this study. Suicidal ideation/risk and history of childhood
maltreatment were assessed with a structured interview and self-report questionnaires. Blood was drawn fromeach participant around noon, and levels of proinflammatory markers (including high-sensitivity CRP, IL-6, andhigh-sensitivity TNF-α) and HPA axis hormones (Cortisol, ACTH, and DHEAS) were measured.
Compared with healthy controls, patients showed significantly higher suicidal ideation and more experience
with childhood maltreatment. For example, 36.2% of the patients endorsed “I would like to kill myself” or “Iwould kill myself if I had the chance” whereas none of the controls did. Suicidal ideation and risk in patientswere significantly associated with childhood maltreatment history. In patients, suicidal ideation wassignificantly positively correlated with high-sensitivity CRP and IL-6 levels, and suicide risk was significantlycorrelated with high-sensitivity CRP levels. Regarding HPA axis hormones, Cortisol and ACTH levels were notsignificantly correlated with any of the indices of suicide. DHEAS levels were significantly negatively
correlated with suicide risk, and the Cortisol/DHEAS ratio was significantly positively correlated with suicidal
ideation and risk.
Our results confirmed that PTSD patients show elevated suicidal ideation/risk, and those with a history ofchildhood maltreatment have an even higher risk of suicide. Our findings suggest that high-sensitivity CRP
levels and Cortisol/DHEAS ratio may serve as state markers of suicide risk in PTSD. Based on these findings
we are planning to explore protective factors for suicide, in addition to risk factors, and to investigate theirassociation with biomarkers. Although the elucidation of how various biological factors affect suicidal behaviors
is a big challenge, it is expected that these lines of research will eventually lead to the development of more
effective suicide countermeasures.

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