Brain serotonin synthesis in adult males characterized by physical aggression during childhood: a 21-year longitudinal study.
BACKGROUND
Adults exhibiting severe impulsive and aggressive behaviors have multiple indices of low serotonin (5-HT) neurotransmission. It remains unclear though whether low 5-HT mediates the behavior or instead reflects a pre-existing vulnerability trait.


RESULTS
In the present study, positron emission tomography with the tracer alpha-[(11)C]methyl-L-tryptophan ((11)C-AMT) was used to compare 5-HT synthesis capacity in two groups of adult males from a 21-year longitudinal study (mean age +/- SD: 27.1+/-0.7): individuals with a history of childhood-limited high physical aggression (C-LHPA; N = 8) and individuals with normal (low) patterns of physical aggression (LPA; N = 18). The C-LHPA males had significantly lower trapping of (11)C-AMT bilaterally in the orbitofrontal cortex and self-reported more impulsiveness. Despite this, in adulthood there were no group differences in plasma tryptophan levels, genotyping, aggression, emotional intelligence, working memory, computerized measures of impulsivity, psychosocial functioning/adjustment, and personal and family history of mood and substance abuse disorders.


CONCLUSIONS
These results force a re-examination of the low 5-HT hypothesis as central in the biology of violence. They suggest that low 5-HT does not mediate current behavior and should be considered a vulnerability factor for impulsive-aggressive behavior that may or may not be expressed depending on other biological factors, experience, and environmental support during development.
Booij
Linda
L
Department of Psychiatry, McGill University, Montreal, Canada.
Tremblay
Richard E
RE
Leyton
Marco
M
Séguin
Jean R
JR
Vitaro
Frank
F
Gravel
Paul
P
Perreau-Linck
Elisabeth
E
Lévesque
Mélissa L
ML
Durand
France
F
Diksic
Mirko
M
Turecki
Gustavo
G
Benkelfat
Chawki
C
D000328:Adult; D000374:Aggression; D001921:Brain / Q000000981:diagnostic imaging / Q000378:metabolism*; D004644:Emotions; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008568:Memory; D049268:Positron-Emission Tomography; D012701:Serotonin / Q000096:biosynthesis*; D014364:Tryptophan / Q000097:blood
D012701:Serotonin; D014364:Tryptophan