Exploring Metabolic Factors and Health-Related Behaviours In Relation to Suicidal Behaviours

Abstract

Background: Suicidal behaviour devastates families, communities, and societies, as well as the millions of individuals who survive suicide attempts. This thesis addresses an urgent need to develop new treatment and intervention strategies for millions of at-risk people by exploring potential metabolic risk factors of suicidal behaviour. Methods: A systematic review and meta-analysis was performed to assess the association between BMI and suicidal behaviour. We explored the association between attempted suicide and various metabolic factors and health behaviours using data from the Determinants of Suicide Conventional and Emergent Risk (DISCOVER) study. DISCOVER is an age and sex matched case-control study comparing adult psychiatric inpatients who had made a recent suicide attempt (n=84) to psychiatric inpatients (n=104) and community members (n=93) who have never attempted suicide. The following potential risk factors were assessed using logistic regression analyses: BMI, waist-circumference, serum total cholesterol, physical activity, tobacco use, and dietary food groups. Results: The systematic review included 38 studies. A meta-analysis established an inverse association between BMI and completed suicide, whereby being underweight is associated with the greatest risk of suicide and being obese or overweight is associated with a deceased risk of suicide relative to normal weight. Evidence for an association between BMI and attempted suicide remains equivocal. The review suggests no association between BMI and suicidal ideation. Analysis of DISCOVER data demonstrated that even a small amount of regular physical activity is significantly associated with decreased risk of attempted suicide. Tobacco use was associated with an increased risk of attempted suicide. Contrary to prior research, obesity, serum-total cholesterol, and diet were not found to be significant risk factors. Conclusion: BMI is inversely related to completed suicide. Obese individuals may be more likely to choose less lethal methods of suicide or may be less susceptible to fatal overdose or self-poisonings. Clinicians should monitor underweight patients for increased risk of suicide. Contrary to prior research, serum total cholesterol, BMI, and waist-circumference were not significantly associated with risk of attempted suicide. Increased physical activity was associated with a decreased risk of attempted suicide, and tobacco use was associated with an increased risk of attempted suicide. While people at risk of attempting suicide tend to use more tobacco products and exercise less than non-suicidal community members, so do non-suicidal psychiatric patients. For this reason, it remains unclear whether smoking habits represent a useful clinical predictor of suicide risk.