title: Free L-tryptophan plasma levels in antisocial violent offenders.
abstract: BACKGROUND
  Several studies have shown that impulsive violent behavior is associated with reduced serotonin metabolism in the brain, but no data exist on possible alterations of the serotonin precursor (free L-tryptophan) levels among violent offenders.
  
  
  OBJECTIVE
  To study free L-tryptophan and kynurenine plasma levels among antisocial violent offenders.
  
  
  METHODS
  Free L-tryptophan and competing amino acid (CAA) plasma levels were measured among 19 male impulsive antisocial violent offenders and 19 age-matched healthy male controls.
  
  
  RESULTS
  Mean free L-tryptophan/(CAA) plasma levels were 160% (95% CI 116%-204%) higher among offenders than controls (P=0.000). Seventeen of the 19 offenders (89.5%) had values of more than 2 SD above the mean value of controls. The levels of kynurenine, the major metabolite of tryptophan, were slightly increased in offenders.
  
  
  CONCLUSIONS
  Free plasma L-tryptophan/CAA levels were markedly increased among antisocial violent offenders indicating a disturbed tryptophan metabolism.
authors.affiliation: Department of Psychiatry, University of Helsinki, P.O. Box 320, 00029 Hus, Finland. jari.tiihonen@hus.fi
authors.forename: J
authors.initials: J
authors.lastname: Tiihonen
authors.forename: M
authors.initials: M
authors.lastname: Virkkunen
authors.forename: P
authors.initials: P
authors.lastname: Räsänen
authors.forename: S
authors.initials: S
authors.lastname: Pennanen
authors.forename: E L
authors.initials: EL
authors.lastname: Sainio
authors.forename: J
authors.initials: J
authors.lastname: Callaway
authors.forename: P
authors.initials: P
authors.lastname: Halonen
authors.forename: J
authors.initials: J
authors.lastname: Liesivuori
mesh_terms: D000328:Adult; D000596:Amino Acids / Q000097:blood; D001923:Brain Chemistry / Q000502:physiology; D003415:Crime / Q000523:psychology*; D006801:Humans; D006897:Hydroxyindoleacetic Acid / Q000134:cerebrospinal fluid; D007737:Kynurenine / Q000097:blood; D008297:Male; D008875:Middle Aged; D012701:Serotonin / Q000378:metabolism; D014364:Tryptophan / Q000097:blood*; D014754:Violence / Q000523:psychology*
chemical_list: D000596:Amino Acids; D012701:Serotonin; D007737:Kynurenine; D006897:Hydroxyindoleacetic Acid; D014364:Tryptophan