title: High interleukin-6 and impulsivity: determining the role of endophenotypes in attempted suicide.
abstract: The dysregulation of inflammation has been associated with depression and, more recently, with suicidal behaviors. The reports regarding the relationship between interleukin-6 (IL-6) and suicide attempts are inconsistent. Personality traits such as impulsivity and aggression are considered endophenotypes and important factors that underlie suicidal behaviors. The aim of the current study was to assess whether plasma and cerebrospinal fluid (CSF) levels of IL-6 are associated with personality traits among suicide attempters. We assessed the relationships among personality traits, IL-6 and violent suicide attempts. The plasma and CSF levels of IL-6 were measured in suicide attempters (plasma=58, CSF=39) using antibody-based immunoassay systems. Personality domains were assessed using the Karolinska Scale of Personality (KSP). IL-6 levels in plasma and CSF were used to predict personality domains via regression models. Plasma IL-6 was significantly and positively correlated with extraversion as well as the KSP subscales impulsivity and monotony avoidance. CSF IL-6 was positively correlated with monotony avoidance. Violent suicide attempts tended to be associated with high plasma IL-6 levels. Plasma and CSF levels of IL-6 were not significantly associated with each other. These results indicate that impulsivity and the choice of a violent suicide attempt method might be related to higher levels of IL-6 in individuals who attempt suicide. The neuroinflammation hypothesis of suicidal behavior on the basis of elevated IL-6 levels might be partly explained by the positive association between IL-6 and impulsivity, which is a key element of the suicidal phenotype.
authors.affiliation: Department of Clinical Neuroscience/Psychiatry, Karolinska Institutet, Karolinska University Hospital, Stockholm, Sweden.
authors.forename: J
authors.initials: J
authors.lastname: Isung
authors.affiliation: Department of Clinical Neuroscience/Psychiatry, Karolinska Institutet, Karolinska University Hospital, Stockholm, Sweden.
authors.forename: S
authors.initials: S
authors.lastname: Aeinehband
authors.affiliation: Department of Clinical Sciences, Danderyd Hospital, Karolinska Institutet, Stockholm, Sweden.
authors.forename: F
authors.initials: F
authors.lastname: Mobarrez
authors.affiliation: Department of Clinical Neuroscience/Psychiatry, Karolinska Institutet, Karolinska University Hospital, Stockholm, Sweden.
authors.forename: P
authors.initials: P
authors.lastname: Nordström
authors.affiliation: Department of Clinical Neuroscience/Psychiatry, Karolinska Institutet, Karolinska University Hospital, Stockholm, Sweden.
authors.forename: B
authors.initials: B
authors.lastname: Runeson
authors.affiliation: Department of Clinical Sciences, Danderyd Hospital, Karolinska Institutet, Stockholm, Sweden.
authors.forename: M
authors.initials: M
authors.lastname: Asberg
authors.affiliation: Department of Clinical Neuroscience/Psychiatry, Karolinska Institutet, Karolinska University Hospital, Stockholm, Sweden.
authors.forename: F
authors.initials: F
authors.lastname: Piehl
authors.affiliation: 1] Department of Clinical Neuroscience/Psychiatry, Karolinska Institutet, Karolinska University Hospital, Stockholm, Sweden [2] Department of Clinical Sciences, Umeå University, Umeå, Sweden.
authors.forename: J
authors.initials: J
authors.lastname: Jokinen
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D058068:Endophenotypes / Q000097:blood* / Q000134:cerebrospinal fluid*; D005260:Female; D006801:Humans; D007175:Impulsive Behavior; D015850:Interleukin-6 / Q000097:blood* / Q000134:cerebrospinal fluid*; D008297:Male; D008875:Middle Aged; D013406:Suicide, Attempted / Q000523:psychology / Q000706:statistics & numerical data*; D055815:Young Adult
chemical_list: D015850:Interleukin-6