The catechol-O-methyltransferase polymorphism: relations to the tonic-phasic dopamine hypothesis and neuropsychiatric phenotypes.

Objective: Involvement of personality traits in susceptibility to suicidality has been the subject of research since the 1950s. Because of the diversity of conceptual and methodological approaches, the extent of their independent contribution has been difficult to establish. Here, we review conceptual background and empirical evidence investigating roles of traits in suicidal behaviors. Method: We selected original studies published in English in MEDLINE and PsycINFO databases, focusing on suicidal ideation, suicide attempts, or suicide completions, and using standardized personality measures. Results: Most studies focused on investigating risk for suicide attempts. Hopelessness, neuroticism, and extroversion hold the most promise in relation to risk screening across all three suicidal behaviors. More research is needed regarding aggression, impulsivity, anger, irritability, hostility, and anxiety. Conclusion: Selected personality traits may be useful markers of suicide risk. Future research needs to establish their contributions in relation to environmental and genetic variation in different gender, age, and ethnocultural groups.

Personality traits as correlates of suicidal ideation, suicide attempts, and suicide completions: a systematic review.

Conduct disorder is a childhood behaviour disorder that is characterized by persistent aggressive or antisocial behaviour that disrupts the child's environment and impairs his or her functioning. A proportion of children with conduct disorder have psychopathic traits. Psychopathic traits consist of a callous-unemotional component and an impulsive-antisocial component, which are associated with two core impairments. The first is a reduced empathic response to the distress of other individuals, which primarily reflects reduced amygdala responsiveness to distress cues; the second is deficits in decision making and in reinforcement learning, which reflects dysfunction in the ventromedial prefrontal cortex and striatum. Genetic and prenatal factors contribute to the abnormal development of these neural systems, and social-environmental variables that affect motivation influence the probability that antisocial behaviour will be subsequently displayed.

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The neurobiology of psychopathic traits in youths

http://www.ikpp.si/att/181/Seo%202008%20Serotonin%20and%20Dopamine%20in%20impulsive%20aggression%20%20Agg.pdf

Role of serotonin and dopamine system interactions in the neurobiology of impulsive aggression and its comorbidity with other clinical disorders

Suicide is a leading cause of death, but it is not well understood or well researched. Our purpose in this review is to summarize extant knowledge on neurobiological and psychological factors involved in suicide, with specific goals of identifying areas particularly in need of future research and of articulating an initial agenda that may guide future research. We conclude that from both neurobiological and psychological perspectives, extant research findings converge on the view that two general categories of risk for suicide can be identified: (a) dysregulated impulse control; and (b) propensity to intense psychological pain (e.g., social isolation, hopelessness), often in the context of mental disorders, especially mood disorders. Each of these categories of risk is underlain at least to some degree by specific genetic and neurobiological factors; these factors in general are not well characterized, though there is emerging consensus that most if not all reside in or affect the serotonergic system. We encourage future theorizing that is conceptually precise, as well as epistemically broad, about the specific preconditions of serious suicidal behavior, explaining the daunting array of suicide-related facts from the molecular to the cultural level.

The Psychology and Neurobiology of Suicidal Behavior

A functional single nucleotide polymorphism (V158M) in the COMT gene is associated with aggressive personality traits.

Since both aggression-related traits and serotonergic activity are partially heritable and correlate inversely, variations in genes of the serotonergic system might then, to some extent, account for variations in aggression-related behavior. Tryptophan hydroxylase (TPH) is the rate limiting biosynthetic enzyme in the serotonin pathway and regulates levels of serotonin. Recently, a genetic variation in TPH has been associated with aggression and anger-related traits in volunteers. We investigated a sample of community-based healthy volunteers (n = 154) and suicide attempters (n = 86), a clinical population with a high risk for elevated impulsive aggression and related traits. The subjects were genotyped for a A218C and a A779C single nucleotide polymorphism (SNP) located in the TPH gene. All subjects were administered standard psychiatric interviews as well as self-report questionnaires for aggression, irritability and anger-related traits. For anger-related traits, a multivariate effect of the tryptophan hydroxylase genotype and an interaction effect for genotype and diagnosis was observed in healthy volunteers and suicide attempters after controlling for age and educational level. U-carriers in both groups showed higher scores for State Anger, Trait Anger and Angry Temperament. These findings support the hypothesis that the A218C and the A779C SNP in the TPH gene may be associated with anger-related traits in German samples.

Association of anger-related traits with SNPs in the TPH gene.

ABCG1 gene variants in suicidal behavior and aggression-related traits

The gene that codes for the ABC transporter ABCG1 is located in a chromosomal susceptibility region (21q22.3) for affective disorders. Genetic variations in ABCG1 have been associated with affective disorders in Japanese males. In this study, we investigated the distribution of a G2457A polymorphism in patients with affective disorders, suicide attempters with various psychiatric diagnoses and healthy subjects. We initially found a trend towards a modest association with affective disorders in males (p = 0.046 for allele frequencies and p = 0.046 for AA versus GG). We conducted a replication study with independent patients and controls. There was no association with affective disorders, either in the replication or in the combined group. Furthermore, we found no association with suicidal behavior. These findings do not support the hypothesis that ABCG1 is a susceptibility gene for affective disorders or suicidal behavior.

/pdf/association-study-of-suicidal-behavior-and-affective-58vqnph830.pdf

A. Gietl

Papers

A functional single nucleotide polymorphism (V158M) in the COMT gene is associated with aggressive personality traits.

Association of anger-related traits with SNPs in the TPH gene.

ABCG1 gene variants in suicidal behavior and aggression-related traits

Association Study of Suicidal Behavior and Affective Disorders with a Genetic Polymorphism in ABCG1, a Positional Candidate on Chromosome 21q22.3

Association study of suicidal behavior and affective disorders with a genetic polymorphism in ABCG1, a positional candidate on chromosome 21q22.3