title: Temperament, character and serotonin activity in the human brain: a positron emission tomography study based on a general population cohort.
abstract: BACKGROUND
  The psychobiological model of personality by Cloninger and colleagues originally hypothesized that interindividual variability in the temperament dimension 'harm avoidance' (HA) is explained by differences in the activity of the brain serotonin system. We assessed brain serotonin transporter (5-HTT) density in vivo with positron emission tomography (PET) in healthy individuals with high or low HA scores using an 'oversampling' study design. Method Subjects consistently in either upper or lower quartiles for the HA trait were selected from a population-based cohort in Finland (n = 2075) with pre-existing Temperament and Character Inventory (TCI) scores. A total of 22 subjects free of psychiatric and somatic disorders were included in the matched high- and low-HA groups. The main outcome measure was regional 5-HTT binding potential (BPND) in high- and low-HA groups estimated with PET and [11C]N,N-dimethyl-2-(2-amino-4-methylphenylthio)benzylamine ([11C]MADAM). In secondary analyses, 5-HTT BPND was correlated with other TCI dimensions.
  
  
  RESULTS
  5-HTT BPND did not differ between high- and low-HA groups in the midbrain or any other brain region. This result remained the same even after adjusting for other relevant TCI dimensions. Higher 5-HTT BPND in the raphe nucleus predicted higher scores in 'self-directedness'.
  
  
  CONCLUSIONS
  This study does not support an association between the temperament dimension HA and serotonin transporter density in healthy subjects. However, we found a link between high serotonin transporter density and high 'self-directedness' (ability to adapt and control one's behaviour to fit situations in accord with chosen goals and values). We suggest that biological factors are more important in explaining variability in character than previously thought.
authors: Department of Psychiatry, University of Turku, Turku, Finland.
authors: L
authors: L
authors: Tuominen
authors: J
authors: J
authors: Salo
authors: J
authors: J
authors: Hirvonen
authors: K
authors: K
authors: Någren
authors: P
authors: P
authors: Laine
authors: T
authors: T
authors: Melartin
authors: E
authors: E
authors: Isometsä
authors: J
authors: J
authors: Viikari
authors: C R
authors: CR
authors: Cloninger
authors: O
authors: O
authors: Raitakari
authors: J
authors: J
authors: Hietala
authors: L
authors: L
authors: Keltikangas-Järvinen
mesh_terms: D000223:Adaptation, Psychological / Q000502:physiology*; D000704:Analysis of Variance; D001596:Benzylamines; D001921:Brain / Q000000981:diagnostic imaging / Q000378:metabolism*; D001931:Brain Mapping; D002250:Carbon Radioisotopes; D002605:Character; D015331:Cohort Studies; D005260:Female; D005387:Finland; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008297:Male; D008960:Models, Psychological; D010555:Personality Inventory; D049268:Positron-Emission Tomography / Q000379:methods; D011485:Protein Binding; D019275:Radiopharmaceuticals; D012044:Regression Analysis; D020377:Self Efficacy; D050486:Serotonin Plasma Membrane Transport Proteins / Q000378:metabolism*; D013694:Temperament / Q000502:physiology*
chemical_list: D001596:Benzylamines; D002250:Carbon Radioisotopes; C470437:N,N-dimethyl-2-(2-amino-4-methylphenylthio)benzylamine; D019275:Radiopharmaceuticals; D050486:Serotonin Plasma Membrane Transport Proteins