Free L-tryptophan plasma levels in antisocial violent offenders.
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.
Tiihonen
J
J
Department of Psychiatry, University of Helsinki, P.O. Box 320, 00029 Hus, Finland. jari.tiihonen@hus.fi
Virkkunen
M
M
Räsänen
P
P
Pennanen
S
S
Sainio
E L
EL
Callaway
J
J
Halonen
P
P
Liesivuori
J
J
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*
D000596:Amino Acids; D012701:Serotonin; D007737:Kynurenine; D006897:Hydroxyindoleacetic Acid; D014364:Tryptophan