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Precursor amino acid concentrations in normal weight bulimics and normal controls
R B Lydiard1, K T Brady, P M O'Neil
1Department of Psychiatry, Medical University of South Carolina, Charleston.
Progress in Neuro-Psychopharmacology & Biological Psychiatry
|January 1, 1988
Summary
This study found no difference in plasma tryptophan ratios between individuals with bulimia nervosa and controls. These findings suggest that reduced tryptophan availability is unlikely to be a cause of bulimia or depression.
Area of Science:
- Neuroscience
- Psychiatry
- Biochemistry
Background:
- Central nervous system (CNS) serotonergic neurotransmission influences appetitive behavior.
- The ratio of plasma tryptophan (TRP) to other large neutral amino acids (LNAA) is thought to regulate CNS serotonin (5-HT) synthesis.
Purpose of the Study:
- To investigate baseline plasma TRP ratios in normal-weight individuals with bulimia nervosa compared to normal controls.
- To assess the relationship between TRP ratios, mood disorders, and bulimic symptomatology.
Main Methods:
- Plasma TRP ratios were measured in 23 normal-weight bulimics and 7 normal controls after an overnight fast.
- Mood disorders were assessed using the Schedule for Affective Disorders and Schizophrenia (SADS) interview and Beck Depression Inventory ratings.
Main Results:
- No significant differences in plasma TRP ratios were observed between bulimics and normal controls.
- TRP ratios did not differ significantly between depressed and nondepressed bulimic individuals.
- Baseline TRP ratios do not appear to reflect potential abnormalities in CNS serotonergic function in bulimia nervosa.
Conclusions:
- Reduced tryptophan availability for serotonin conversion is unlikely to be the common biological abnormality in depression and bulimia.
- Further research into the dynamic aspects of the serotonergic system in bulimia nervosa is warranted.