Abstract
INTRODUCTION: Caffeine, in the form of coffee, tea and energy drinks, is recognised as the world's most utilised psychoactive substance and consumed by approximately 80% of the global population daily. Emerging studies have suggested a more complex relationship in terms of the mental health outcomes that can arise after consumption. This is the first systematic review and meta-analysis that aims to explore the effects of caffeine consumption on the risk of suicide attempts, ideation and self-harm. METHODS: This PRISMA-adherent systematic review involved a systematic search of PubMed, Embase, Cochrane and PsycINFO for all studies that evaluated the effects of caffeine consumption on the risk of suicide attempts, ideation and self-harm. Random effects meta-analyses and meta-regression were used for primary analysis. RESULTS: Seventeen studies were included. The results demonstrated that coffee consumption of more than 60 cups per month significantly decreases the risk of suicide attempts. In contrast, energy drink consumption from as low as one cup per month was significantly associated with an increased risk of both suicide attempts and ideation. Meta-regression demonstrated a strong association between the dosage consumed and suicidality outcomes. Systematic review highlighted that male gender and substance usage significantly increased caffeine consumption. CONCLUSION: The results studied the associations between coffee and energy drink intake with suicide risk and suicidal ideation. Coffee intake was associated with reduced odds of suicide ideation and attempts, while consuming energy drinks was associated with an increased risk of both adverse outcomes. Further studies would be essential to elucidate the psychosocial factors and causative links underlying this association. Understanding the relationship between caffeine consumption and mental health outcomes is crucial to develop public health strategies to boost the mental health of consumers.