Relationships of plasma tryptophan availability to course of illness and clinical features of alcoholism: a preliminary study.
BACKGROUND
Serotonergic (5-HT) mechanisms may be involved in impulse control (including antisocial behavior) across psychiatric syndromes. Age of onset may differentiate alcoholics on psychopathological characteristics associated with impulse control, especially mood disturbance, hostility, and a broad range of antisocial behaviors. Thus, there may be a predictable relationship between markers of 5-HT function and age of onset-related characteristics.


OBJECTIVE
We tested the hypothesis that there would be a predictable relationship between the ratio of plasma tryptophan to large neutral amino acids (i.e. TRYP/LNAA ratio), a marker of 5-HT function, age of onset and related psychopathological characteristics associated with impulse control.


METHODS
Fifty-eight male and female DSM-IV diagnosed alcoholics attending an outpatient treatment center completing a comprehensive psychopathological assessment, and from whom blood samples were obtained.


RESULTS
Plasma TRYP/LNAA ratio was positively correlated with symptoms of dysphoria, and negatively associated with harm avoidance on Cloninger's Temperament and Character Inventory. Low tryptophan availability was associated with antisocial-type personality characteristics. Interestingly, the few (nine) subjects who had both early onset alcoholism and antisocial personality disorder had a higher plasma tryptophan but similar TRYP/LNAA ratio to the others.


CONCLUSIONS
These data suggest that a low plasma TRYP/LNAA ratio is associated with susceptibility to anxiety, antisocial-type personality characteristics, and an early age of onset for alcoholism. In contrast, a high plasma TRYP/LNAA ratio is associated with a later onset of alcoholism and dysphoria.
Swann
A C
AC
University of Texas-Houston Health Science Center, USA.
Johnson
B A
BA
Cloninger
C R
CR
Chen
Y R
YR
D017668:Age of Onset; D000437:Alcoholism / Q000097:blood* / Q000523:psychology; D000596:Amino Acids / Q000097:blood*; D001682:Biological Availability; D003863:Depression / Q000523:psychology; D007174:Disruptive, Impulse Control, and Conduct Disorders / Q000523:psychology; D005260:Female; D006791:Hostility; D006801:Humans; D008297:Male; D019964:Mood Disorders / Q000523:psychology; D012701:Serotonin / Q000097:blood*; D014364:Tryptophan / Q000493:pharmacokinetics*
D000596:Amino Acids; D012701:Serotonin; D014364:Tryptophan