A pilot study of repeated suicide attempts in persons hospitalized for depression: The role of immune factors

Background: Individuals with major depressive disorder (MDD) hospitalized for a suicide attempt are at high risk for a repeated suicide attempt. Previous studies have identified immune alterations in MDD, but not the prospective association between immunological abnormalities and subsequent suicide behavior. Methods: We enrolled 69 adults with MDD following hospitalization for a suicide attempt. Participants were assessed for co-occurring immunological disorders and on clinical measures. Participants had a blood sample drawn from which were measured cytokines, antibodies, and other markers of inflammation. Following hospital discharge, participants were assessed for six months. Cox proportional hazard models examined the relationships between baseline variables and a repeated suicide attempt. Results: A total of 15 (24 %) of the 62 participants with at least one post-hospital visit had a suicide attempt in the follow-up period. These individuals had a significant alteration in a combined immune marker consisting of the cytokines, IL-1β, TNF-α, and IFN‐γ as well as IgG antibodies to Epstein Barr Virus (HR= 8.03, 95 % CI 1.73, 37.08, p=.008). A diagnosis of asthma was also associated with a repeated suicide attempt (HR= 3.10, 95 % CI 1.10, 8.79, p=.033). Suicidal intent, stressful events, and aspects of psychiatric history also predicted this outcome. Limitations: The sample was relatively small limiting statistical power. Also, we focused on one specific high-risk group. Conclusions: Persons with MDD and immunological abnormalities have an increased rate of repeated suicide attempts. Immunological measurements combined with clinical information may identify high risk individuals who would benefit from personalized interventions.