title: Kynurenic acid and psychotic symptoms and personality traits in twins with psychiatric morbidity.
abstract: Increased cytokines and kynurenic acid (KYNA) levels in cerebrospinal fluid (CSF) have been reported in patients with schizophrenia and bipolar disorder. The aim of the present study was to investigate cytokines and kynurenines in the CSF of twin pairs discordant for schizophrenia or bipolar disorder and to study these CSF markers in relation to psychotic symptoms and personality traits. CSF levels of tryptophan (TRP), KYNA, quinolinic acid (QUIN), interleukin (IL)-6, IL-8 and tumor necrosis factor-alpha (TNF-α) were analyzed in 23 twins with schizophrenia or bipolar disorder, and in their not affected co-twins. Ratings of psychotic symptoms and personality traits were made using the Scales for Assessment of Negative and Positive symptoms, the Structured Clinical Interview for DSM-IV - Axis II Disorders, and the Schizotypal Personality Questionnaire - Brief. A total score for psychotic symptoms and personality traits was constructed for analysis. CSF KYNA was associated with the score for psychotic symptom and personality traits. TNF-α and IL-8 were associated, and the intra-pair differences scores of TNF-α and IL-8 were highly correlated. Intraclass correlations indicated genetic influences on CSF KYNA, TRP, IL-8 and TNF-α. The association between KYNA and psychotic symptoms further supports a role of KYNA in psychotic disorders.
authors.affiliation: Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Magdalena E
authors.initials: ME
authors.lastname: Kegel
authors.affiliation: Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden. Electronic address: viktoria.johansson@ki.se.
authors.forename: Viktoria
authors.initials: V
authors.lastname: Johansson
authors.affiliation: Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Lennart
authors.initials: L
authors.lastname: Wetterberg
authors.affiliation: Protein Biomarkers, Personalized Healthcare & Biomarker Laboratories, Innovative Medicines, Gothenburg, Sweden.
authors.forename: Maria
authors.initials: M
authors.lastname: Bhat
authors.affiliation: Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Lilly
authors.initials: L
authors.lastname: Schwieler
authors.affiliation: Departments of Psychology and Psychiatry, Yale University, New Haven, USA.
authors.forename: Tyrone D
authors.initials: TD
authors.lastname: Cannon
authors.affiliation: Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden; AstraZeneca, Research & Development, Innovative Medicines, Personalized Healthcare & Biomarkers, Translational Science Centre, Science for Life Laboratory, Solna, Sweden.
authors.forename: Ina
authors.initials: I
authors.lastname: Schuppe-Koistinen
authors.affiliation: Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Göran
authors.initials: G
authors.lastname: Engberg
authors.affiliation: Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden; Institute of Neuroscience and Physiology, University of Gothenburg, Gothenburg, Sweden.
authors.forename: Mikael
authors.initials: M
authors.lastname: Landén
authors.affiliation: Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Christina M
authors.initials: CM
authors.lastname: Hultman
authors.affiliation: Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Sophie
authors.initials: S
authors.lastname: Erhardt
mesh_terms: D001714:Bipolar Disorder / Q000134:cerebrospinal fluid* / Q000523:psychology; D005260:Female; D006801:Humans; D015850:Interleukin-6 / Q000134:cerebrospinal fluid; D016209:Interleukin-8 / Q000134:cerebrospinal fluid; D007736:Kynurenic Acid / Q000134:cerebrospinal fluid*; D008297:Male; D008875:Middle Aged; D010551:Personality; D011618:Psychotic Disorders / Q000150:complications; D017378:Quinolinic Acid / Q000134:cerebrospinal fluid; D012559:Schizophrenia / Q000134:cerebrospinal fluid*; D012565:Schizophrenic Psychology; D014364:Tryptophan / Q000134:cerebrospinal fluid; D014409:Tumor Necrosis Factor-alpha / Q000134:cerebrospinal fluid; D014427:Twins / Q000523:psychology*
chemical_list: D015850:Interleukin-6; D016209:Interleukin-8; D014409:Tumor Necrosis Factor-alpha; D014364:Tryptophan; D017378:Quinolinic Acid; D007736:Kynurenic Acid
keywords: Bipolar disorder; Cerebrospinal fluid; Kynurenic acid; Neuroinflammation; Schizophrenia; Twin studies