Suicidal thoughts and behaviors are elevated among active-duty service members (ADSM) and veterans compared to the general population. Hence, it is a priority to examine maintenance factors underlying suicidal ideation among ADSM and veterans to develop effective, targeted interventions. In particular, interpersonal risk factors, hopelessness, and overarousal have been robustly connected to suicidal ideation and intent.

To identify the suicidal ideation risk factors that are most relevant, we employed network analysis to examine between-subjects (cross-sectional), contemporaneous (within seconds), and temporal (across four hours) group-level networks of suicidal ideation and related risk factors in a sample of ADSM and veterans (participant n = 92, observations n = 10 650). Participants completed ecological momentary assessment (EMA) surveys four times a day for 30 days, where they answered questions related to suicidal ideation, interpersonal risk factors, hopelessness, and overarousal.

The between-subjects and contemporaneous networks identified agitation, not feeling close to others, and ineffectiveness as the most central symptoms. The temporal network revealed that feeling ineffective was most likely to influence other symptoms in the network over time.

Our findings suggest that ineffectiveness, low belongingness, and agitation are important drivers of moment-to-moment and longitudinal relations between risk factors for suicidal ideation in ADSM and veterans. Targeting these symptoms may disrupt suicidal ideation.

The interpersonal theory of suicide (IPTS) is one of the most intensively researched contemporary theories on the development of suicidal ideation and behaviour. However, there is a lack of carefully conducted prospective studies.

To evaluate the main predictions of the IPTS regarding the importance of perceived burdensomeness, thwarted belongingness and capability for suicide in predicting future suicide attempts in a prospective design.

Psychiatric in-patients (n = 308; 53.6% (n = 165) female; mean age 36.82 years, s.d. = 14.30, range 18–81) admitted for severe suicidal ideation (n = 145, 47.1%) or a suicide attempt completed self-report measures of thwarted belongingness, perceived burdensomeness, capability for suicide, hopelessness, depression and suicidal ideation as well as interviews on suicide intent and suicide attempts and were followed up for 12 months. Logistic regression and receiver operating characteristics (ROC) analysis were conducted.

The interaction of perceived burdensomeness, thwarted belongingness and capability for suicide was not predictive of future suicide attempts, but perceived burdensomeness showed a significant main effect (z = 3.49, P < 0.01; OR = 2.34, 95% CI 1.59–3.58) and moderate performance in screening for future suicide attempts (area under the curve AUC = 0.729, P < 0.01).

The results challenge the theoretical validity of the IPTS and its clinical utility – at least within the methodological limitations of the current study. Yet, findings underscore the importance of perceived burdensomeness in understanding suicidal ideation and behaviour.

Over half of individuals with eating disorders experience suicidal ideation at some point in their lives, yet few longitudinal studies have examined predictors of ideation in this at-risk group. Moreover, prospective research has focused on relatively distal or trait-level factors that are informative for distinguishing who is most at risk but not when. Little is known about more proximal or state-level risk factors that fluctuate within an individual, which is critical for determining when a person is most likely to engage in suicidal behaviors.

Women (N = 97) receiving treatment for their eating disorder completed questionnaires weekly to assess suicidal ideation and interpersonal constructs (i.e. perceived burdensomeness, thwarted belongingness) theorized to be proximal predictors of suicidal desire. Longitudinal multilevel models were conducted to examine both within- and between-person predictors of suicidal ideation across 12 weeks of treatment.

Statistically significant within-person effects for burdensomeness (β = 0.06; p < 0.001) indicate that when individuals have greater feelings of burdensomeness compared to their own average, they also experience higher suicidal ideation. We did not find any significant influence of thwarted belongingness or the interaction between burdensomeness and belongingness on suicidal ideation.

This study was the first to examine dynamic associations between interpersonal constructs and suicidal ideation in individuals with eating disorders. Results are only partially consistent with the Interpersonal Theory of Suicide and suggest that short-term changes in burdensomeness may impact suicidal behavior in individuals with eating disorders.