Stijn Bijttebier

Suicidal brains: A review of functional and structural brain studies in association with suicidal behaviour

Evidence of an association between a vulnerability to suicidal behaviour and neurobiological abnormalities is accumulating. Post-mortem studies have demonstrated structural and biochemical changes in the brains of suicide victims. More recently, imaging techniques have become available to study changes in the brain in vivo. This systematic review of comparative imaging studies of suicidal brains shows that changes in the structure and functions of the brain in association with suicidal behaviour are mainly found in the orbitofrontal and dorsolateral parts of the prefrontal cortex. Correlational studies suggest that these changes relate to neuropsychological disturbances in decision-making, problem solving and fluency, respectively. As a consequence, the findings from these studies suggest that suicidal behaviour is associated with (1) a particular sensitivity to social disapproval (2) choosing options with high immediate reward and (3) a reduced ability to generate positive future events. Further study is needed to elaborate these findings and to investigate to what extent changes in the structure and function of suicidal brains are amenable to psychological and/or biological interventions.

Is there a neuroanatomical basis of the vulnerability to suicidal behavior? A coordinate-based meta-analysis of structural and functional MRI studies

Objective: We conducted meta-analyses of functional and structural neuroimaging studies comparing adolescent and adult individuals with a history of suicidal behavior and a psychiatric disorder to psychiatric controls in order to objectify changes in brain structure and function in association with a vulnerability to suicidal behavior. Methods: Magnetic resonance imaging studies published up to July 2013 investigating structural or functional brain correlates of suicidal behavior were identified through computerized and manual literature searches. Activation foci from 12 studies encompassing 475 individuals, i.e., 213 suicide attempters and 262 psychiatric controls were subjected to meta-analytical study using anatomic or activation likelihood estimation (ALE). Result: Activation likelihood estimation revealed structural deficits and functional changes in association with a history of suicidal behavior. Structural findings included reduced volumes of the rectal gyrus, superior temporal gyrus and caudate nucleus. Functional differences between study groups included an increased reactivity of the anterior and posterior cingulate cortices. Discussion: A history of suicidal behavior appears to be associated with (probably interrelated) structural deficits and functional overactivation in brain areas, which contribute to a decision-making network. The findings suggest that a vulnerability to suicidal behavior can be defined in terms of a reduced motivational control over the intentional behavioral reaction to salient negative stimuli.

The Role of Neuroimaging in Our Understanding of the Suicidal Brain

This paper provides a review of the literature on neuroimaging studies of suicidal behaviour, and discusses the relevance of these studies for our understanding of suicidal behaviour. Main findings from molecular imaging studies include a reduced prefrontal perfusion or metabolism and a blunted increase in activation when challenged in association with a history of suicide attempts. Moreover, impairment of the prefrontal serotonergic system in association with suicidal behaviour is demonstrated in a number of studies. Recent structural and functional imaging studies show changes in cortical and subcortical areas and their connections. A number of methodological issues hamper the interpretation of findings. Nevertheless, when findings from studies using divergent techniques are taken together there is increasing evidence of the involvement of a fronto-cingulo-striatal network in suicidal behaviour. This involvement is supported additionally by findings from neuropsychological studies, which demonstrate changes in decision-making processes in association with suicidal behaviour that rely on the same network. Further study is needed to translate the increasing knowledge from neuroimaging studies in clinical tools for the prediction and prevention of suicidal behaviour.

The Vulnerability to Suicidal Behavior is Associated with Reduced Connectivity Strength

Suicidal behavior constitutes a major public health problem. Based on the stress–diathesis model, biological correlates of a diathesis might help to predict risk after stressor-exposure. Structural changes in cortical and subcortical areas and their connections have increasingly been linked with the diathesis. The current study identified structural network changes associated with a diathesis using a whole-brain approach by examining the structural connectivity between regions in euthymic suicide attempters (SA). In addition, the association between connectivity measures, clinical and genetic characteristics was investigated. We hypothesized that SA showed lower connectivity strength, associated with an increased severity of general clinical characteristics and an elevated expression of short alleles in serotonin polymorphisms. Thirteen euthymic SA were compared with fifteen euthymic non-attempters and seventeen healthy controls (HC). Clinical characteristics and three serotonin-related genetic polymorphisms were assessed. Diffusion MRI together with anatomical scans were administered. Preprocessing was performed using Explore DTI. Whole brain tractography of the diffusion-weighted images was followed by a number of streamlines-weighted network analysis using NBS. The network analysis revealed decreased connectivity strength in SA in the connections between the left olfactory cortex and left anterior cingulate gyrus. Furthermore, SA had increased suicidal ideation, hopelessness and self-reported depression, but did not show any differences for the genetic polymorphisms. Finally, lower connectivity strength between the right calcarine fissure and the left middle occipital gyrus was associated with increased trait anxiety severity (rs = −0.78, p < 0.01) and hopelessness (rs = −0.76, p < 0.01). SA showed differences in white matter network connectivity strength associated with clinical characteristics. Together, these variables could play an important role in predicting suicidal behavior.

Is There a Neuroanatomical Basis for the Vulnerability to Suicide

Is there a neuroanatomical basis for the vulnerability to suicide? Kees van Heeringen MD PhD Unit for Suicide Research Ghent University, Belgium 1. Objectives Suicidal behaviour is the consequence of the interaction between stressors and a diathesis or vulnerability. Evidence is accumulating that changes in the central nervous system contribute to this vulnerability. A substantial number of imaging studies in suicide attempters have been published, but most studies are characterized by small sample sizes and increased risk of false positive findings. Therefore, the current study aimed at a systematic review and meta-analysis of published study in order to describe consistently identified disturbances in brain structure and, or, functions. 2. Methods Systematic review and meta-analysis of imaging studies of attempted suicide patients, affective controls and healthy volunteers, including structural and functional MRI studies and molecular imaging studies. 3. Results A reduced prefrontal perfusion or metabolism, a blunted increase in activation when challenged, and impairment of the prefrontal serotonergic system in association with a history of suicide attempts is shown in molecular imaging studies. Recent structural and functional imaging studies show changes in cortical and subcortical areas and their connections. Meta-analyses revealed structural deficits and functional changes in association with a history of suicidal behaviour. Structural findings included reduced volumes of the rectal gyrus, superior temporal gyrus and caudate nucleus. Functional differences between study groups included an increased reactivity of the anterior and posterior cingulate cortices to negatively valenced emotional stimuli. A number of methodological issues hamper the interpretation of findings. Nevertheless, there is increasing evidence of the involvement of a serotonin-mediated network in suicidal behaviour. The involvement of this network in decision-making, and particularly the prediction of reward and punshment, has been shown previously in healthy individuals. 4. Conclusions A diathesis to suicidal behaviour appears to be associated with changes in biochemical, functional and structural brain characteristics, which point at the involvement of a serotonin-mediated decision-making network in the development of suicidal behaviour.

Functional Brain Imaging of Suicidal Behavior

Suicidal behaviour poses a major challenge to clinicians and health policy makers due to its difficult prediction and prevention, and its substantial impact at individual and societal levels. Although current research focuses particularly on the biological causes of suicidal behaviour, surprisingly little use has been made of structural and functional neuroimaging in order to increase our understanding of the suicidal brain. This chapter reviews the few available studies that have utilized functional neuroimaging, including brain perfusion and receptor ligand studies. The results of these studies have contributed to the development of the suicidal brain concept. The suicidal brain is thought to be composed of the frontotemporal cortex (in connection with the hippocampus) and the prefrontal cortex (in conjunction with the amygdala). These structures appear to be involved in the social cognitive and behavioural expressive components of the suicidal brain. Evidence is increasingly showing, among others using functional neuroimaging techniques, that these two components are involved in the neurobiologically mediated basic neuropsychological dysfunctions associated with suicidal behaviour.

Human Imaging Studies of Suicidal Behavior and its Risk Factors

This chapter reviews neuroimaging studies of suicidal behavior and its major risk factors, and discusses the relevance of the findings for the understanding, prediction, and prevention of suicide. Functional and structural imaging studies show a reduced prefrontal perfusion or metabolism and a blunted increase in activation when challenged in association with a history of suicide attempts. Moreover, impairment of the prefrontal serotonergic system in association with suicidal behavior is demonstrated in a number of studies. Recent structural and functional imaging studies show changes in cortical and subcortical areas and their connections in association with suicidal behavior and risk factors, such as hopelessness, impulsivity, and aggression. The global picture that emerges from these studies reflects the involvement of a fronto-cingulo-striatal network in the development of suicidal behavior. The relevance of these findings for our understanding of suicidal behavior is supported by findings from neuropsychological studies in suicide attempters, showing dysfunctions in neuropsychological domains, which involve similar neuroanatomical regions. Further study is needed to translate the increasing knowledge from neuroimaging studies in clinical tools for the prediction and prevention of suicidal behavior.