Free L-tryptophan plasma levels in antisocial violent offenders

Area of Science:

• Neurobiology
• Biochemistry
• Forensic Psychiatry

Background:

• Impulsive violent behavior is linked to reduced brain serotonin metabolism.
• No prior data existed on serotonin precursor levels in violent offenders.

Purpose of the Study:

• To investigate free L-tryptophan and kynurenine plasma levels in antisocial violent offenders.
• To explore potential alterations in tryptophan metabolism associated with violent behavior.

Main Methods:

• Measured plasma levels of free L-tryptophan and competing amino acids (CAA).
• Compared levels between 19 impulsive antisocial violent offenders and 19 healthy male controls.
• Analyzed kynurenine, a major tryptophan metabolite.

Main Results:

• Free L-tryptophan/CAA plasma levels were 160% higher in offenders than controls (P=0.000).
• 89.5% of offenders had levels exceeding 2 standard deviations above the control mean.
• Kynurenine levels showed a slight increase in offenders.

Conclusions:

• Markedly increased free plasma L-tryptophan/CAA levels were observed in antisocial violent offenders.
• These findings indicate a disturbed tryptophan metabolism in this population.
• Suggests a potential neurobiological marker for violent behavior.