Suicidal Ideation and Behavior
Authors:   , Wiebenga Jasper Xiao Ming 
Published: July 2024

Globally, the annual age-standardized suicide rate is 9 per 100,000 individuals. In the Netherlands, we are faced with an average of 5 suicides per day. While mental health disorders, like depressive or anxiety disorders, elevate suicide risk, these conditions alone are insufficient for determining who will develop suicidal thoughts and which suicidal individuals will act on suicidal thoughts via a suicide attempt. Enhancing suicide risk detection requires a nuanced understanding of suicidal processes within specific mental health disorder populations. Hence, the goals of this thesis were to: 1) investigate the prevalence and course of suicide ideation and attempts in individuals with a depressive and/or anxiety disorder and 2) examine risk determinants (sociodemographics, clinical, personality, psychosocial and (neuro)biological) and mechanisms of suicide ideation and attempts in psychiatric populations.

The goals were investigated using data from two different studies: The Netherlands Study of Depression and Anxiety (NESDA) and Trauma tO Personality Spectrum Study (TOPSS). The main aims of NESDA are to study the longitudinal course of depression and anxiety and their predictors and repercussions. The NESDA sample consists of 2981 respondents between 18 and 65 years old form different areas in The Netherlands and multiple follow-up measurements have been completed across 9-years since the baseline measurement. The presence of a depressive and/or anxiety disorder as defined by the DSM-IV classification system was assessed using a structured diagnostic interview. Suicide outcomes were measured in several ways. The Scale for Suicidal Ideation was used to measure suicide ideation and a history of suicide attempts was measured using a question developed by the WHO/Euro multicenter study on parasuicide. The cross-sectional observational study TOPSS contains 120 respondents between the age of 18 and 65 years with a personality disorder and/or post-traumatic stress disorder as defined by the DSM-IV that were recruited at the specialized outpatient department of mental healthcare center GGZ inGeest in The Netherlands.

Chapter 2 of the thesis provides information on the prevalence of suicide ideation and attempts across a 9-year timespan and a synthesis of NESDA articles that investigated the course and most important cross-sectional and longitudinal determinants of suicide ideation and attempts found so far. Chapter 3 examined the extent to which various sociodemographic, clinical, personality and psychosocial variables can distinguish individuals that attempt suicide from those that only think about suicide and non-suicidal individuals. Next, associations between individual markers and cumulative indices of three major physiological stress systems and suicide ideation and attempts were investigated in Chapter 4. Chapter 5 built upon findings in Chapter 3 by investigating to what extent the association found between higher levels of childhood trauma and suicide ideation and suicide attempts is mediated by psychosocial, personality, lifestyle, and biological variables. In Chapter 6, the association between personality traits and suicide ideation and attempts was investigated among individuals with a personality disorder. Finally, all of the results from the previous chapters were combined and discussed and ideas for future research directions and clinical implications of the results were considered in Chapter 7.