Reduced peripheral BDNF levels are associated with suicide attempts across various psychiatric disorders: A...

Brain-derived neurotrophic factor (BDNF) is a crucial protein marker involved in neurogenesis and synaptic plasticity. Its role in suicidal behaviour has been widely implicated with inconsistent findings across diverse studies. This systematic review and meta-analysis evaluated the peripheral BDNF levels among psychiatric patients with a history of suicide attempt (SA) compared to psychiatric controls (PCs) without SA.

PubMed, Web of Science, and EMBASE were systematically searched as per the defined study protocol prospectively registered in PROSPERO [CRD420261412668]. A random-effects (RE) model was used to pool standardised mean differences (SMDs) and 95% confidence intervals (CIs). Subgroup analyses, meta-regression, sensitivity analyses, and publication bias assessments were also performed to explore sources of heterogeneity.

A total of 20 studies, including 667 SA and 952 PC, were quantitatively pooled. We found significantly lower peripheral BDNF levels in SA than PC [SMD = -0.26; 95% CI = -0.43,-0.09; p = 0.002]. During subgroup analysis, significant associations were found in plasma samples among depressed patients, medication-naïve/free and medicated patients, recent SA, and in both fasting and non-fasting samples. However, no significant subgroup differences were observed. Additionally, meta-regression analysis did not reveal significant moderators affecting the pooled estimates, and the findings were robust in sensitivity analyses, with no evidence of publication bias.

Peripheral BDNF levels are significantly lower in psychiatric patients with a lifetime history of SA across diverse clinical and methodological settings. These findings suggest a potential role for BDNF as a transdiagnostic biological correlate of suicide attempts.