function which is negatively related to risk of suicide. Furthermore, nicotine, the addictive substance in all kinds of tobacco products, is a potent activator of the hypothalamic-pituitary-adrenal (HPA) axis and is able to activate the attenuated responsiveness of the HPA axis to psychological stress. On the other hand, hyperactivity of the HPA axis is supposed to be a risk factor for suicidal behaviors (DeBry & Tiffany, 2008; Durazzo et al., 2010; van Heeringen & Mann, 2014).
