Clinical meaning
Suicide is the 10th leading cause of death in the US and the 2nd leading cause among ages 10-34. Suicidal behavior exists on a spectrum: suicidal ideation (passive -- wishing to be dead; active -- thinking about methods), suicidal planning (formulating a specific plan with method, time, place), suicidal intent (determination to carry out the plan), and suicide attempt (self-injurious behavior with intent to die). Non-suicidal self-injury (NSSI) is distinct: self-harm WITHOUT intent to die, serving functions including emotion regulation (reducing overwhelming affect), self-punishment, communication of distress, or feeling something when emotionally numb. NSSI and suicidal behavior can co-occur, and NSSI is a RISK FACTOR for future suicide attempts. Neurobiologically, suicidal behavior involves serotonin system dysfunction (reduced serotonergic function in the prefrontal cortex impairing impulse control and decision-making), HPA axis dysregulation (elevated cortisol reflecting chronic stress), inflammatory markers (elevated IL-6, TNF-alpha in suicidal patients), and reduced BDNF (brain-derived neurotrophic factor reflecting impaired neuroplasticity). The interpersonal theory of suicide (Joiner) identifies three factors: thwarted belongingness (feeling disconnected), perceived burdensomeness (believing others would be better off without them), and acquired capability (habituation...