BDNF, impulsiveness and avoidant focused coping in suicide attempters

Abstract: Brain-derived neurotrophic factor (BDNF) is an important protein for neuroplasticity and neurogenesis. In this thesis the role of BDNF, in suicidal behaviour was investigated with focus on possible risk factors for suicidal behaviour such as avoidant focused coping, dysfuntional personality traits like impulsiveness and hyperactivity of the Hypothalamic-Pituitary-Adrenal (HPA) axis.Paper I: The association between avoidant focused coping and the BDNF Val66Met gene polymorphism in two different cohorts of suicide attempters was investigated. The Met allele of this gene polymorphism was associated with increased use of avoidant focused coping, irrespectively of age and the severity of depressive symptoms. Paper II: The relationships between BDNF in plasma, clinical symptoms and personality dimensions were studied in recent suicide attempters. BDNF concentrations in plasma were correlated significantly with Solidity but not with symptoms of depression or anxiety.Paper III: The association between BDNF in plasma and HPA axis activity in recent suicide attempters was investigated. Plasma BDNF concentrations were correlated significantly and negatively with post-dexamethasone cortisol in female but not in male suicide attempters. Paper IV: The association between avoidant coping strategies, suicide risk measured with the Suicide assessment self-rating scale (SUAS-S) and suicidal ideation was studied in two different cohorts of suicide attempters, and in a cohort of depressed patients without a history of attempted suicide. Regression analyses revealed significant positive correlations between avoidant coping strategies and the total scores of SUAS-S adjusted for age, gender, the severity of depressive symptoms and the co-morbidity with personality disorder in both cohorts of suicide attempters and in depressed patients without a history of attempted suicide. Furthermore, a significant correlation between more severe suicidal ideations and increased use of avoidant focused coping was observed in all three cohorts of patients.Paper V: The relationship between avoidant focused coping and personality traits in recent suicide attempters and in healthy controls was examined. Avoidant focused coping was correlated significantly with Solidity in suicide attempters. The finding remained significant after controlling for age and gender. Conclusion: The results indicate that there are associations between BDNF, impulsiveness and HPA axis hyperactivity in suicide attempters. Furthermore, an increased use of avoidant focused coping is suggested as a risk factor for suicidal behaviour in psychatric patients.