Association between suicidal thoughts and behaviours and markers of autonomic functioning and regulation in adults: A systematic review and meta-analysis

Currently, the identification of individuals experiencing suicidal thoughts and behaviours (STBs) rely predominantly on self-report. Previous research on children and young people highlighted an association between difficulties in arousal regulation (reflected, for example, in reduced heart rate variability and altered electrodermal activity patterns) and STBs, but this has not been meta-analytically explored in adults. This systematic review and meta-analysis aimed to quantify the association between STBs and markers of autonomic functioning/regulation in adults. Based on a pre-registered protocol (PROSPERO CRD42024596886), we searched PubMed/MEDLINE, Embase, PsycINFO and Web of Science until 2nd August 2025 for empirical studies assessing the association between measures of autonomic functioning and/or regulation and STBs in adults. Quality of cross-sectional and cohort studies was assessed through the Newcastle-Ottawa Scale. Pooled effect sizes (Hedge's g) were estimated with random-effects meta-analytic models in R. Out of 2726 articles screened, 40 studies were included in the systematic review, and 22 in the meta-analyses (6290 individuals, 28% with STBs). We found reduced heart rate variability in adults with STBs (g = -0.2469, p = 0.0069) but no significant associations between electrodermal activity patterns and STBs (g = -0.2563, p = 0.3953). Our results highlight the relationship between reduced cardiac regulation and STBs, providing a rationale for further exploration of cardiac regulation as a potential objective marker for assessing and monitoring STBs in adults. Further research is warranted to understand how these markers can be used in clinical practice to assess and support the management of suicide risk in adults.