Effects of a novel method of acute tryptophan depletion on plasma tryptophan and cognitive performance in healthy volunteers.

@article{citeulike:1115578, abstract = {RATIONALE: Disorders associated with low levels of serotonin (5-HT) are characterized by mood and cognitive disturbances. Acute tryptophan depletion (ATD) is an established method for lowering 5-HT levels and an important tool to study the effects of reduced 5-HT on mood and cognition in human subjects. The traditional ATD method, i.e., administration of separate amino acids (AAs), has several disadvantages. The AA mixture is costly, unpalatable and associated with gastrointestinal discomfort. OBJECTIVES: The University of Maastricht developed a new and inexpensive method for ATD: a natural collagen protein (CP) mixture with low tryptophan (TRP) content. The reductions in plasma TRP after taking this CP mixture were compared with the reductions achieved taking the traditional AA mixture, and effects on memory and reversal learning were studied. METHODS: Fifteen healthy young volunteers participated in a double-blind, counterbalanced within-subject study. Reversal learning, verbal memory and pattern recognition were assessed at baseline and 3-4 h after taking the CP mixture. RESULTS: The new ATD method significantly reduced plasma TRP by 74\% and the ratio between TRP and the other large AAs (TRP/LNAA) by 82\%. The placebo mixture did not change these measures. Delayed recognition reaction time on the verbal learning task was increased following ATD. No other cognitive effects were found. CONCLUSIONS: The CP mixture was shown to be an efficient tool for lowering plasma TRP in humans. The validity of this method with regard to behavioral changes remains to be established in healthy, vulnerable and clinical populations.}, address = {Department of Psychiatry and Neuropsychology (DRT10), Brain and Behavior Institute, Maastricht University, P.O. Box 616, Maastricht, 6200, The Netherlands. l.evers@np.unimaas.nl}, author = {Evers, E. A. and Tillie, D. E. and van der Veen, F. M. and Lieben, C. K. and Jolles, J. and Deutz, N. E. and Schmitt, J. A. }, citeulike-article-id = {1115578}, doi = {10.1007/s00213-004-2141-y}, issn = {0033-3158}, journal = {Psychopharmacology (Berl)}, keywords = {tryptophan\_depletion}, month = {February}, number = {1}, pages = {92--99}, posted-at = {2007-02-21 03:53:01}, priority = {5}, title = {Effects of a novel method of acute tryptophan depletion on plasma tryptophan and cognitive performance in healthy volunteers.}, url = {http://dx.doi.org/10.1007/s00213-004-2141-y}, volume = {178}, year = {2005} }

TY - JOUR ID - citeulike:1115578 L3 - citeulike-article-id:1115578 TI - Effects of a novel method of acute tryptophan depletion on plasma tryptophan and cognitive performance in healthy volunteers. JF - Psychopharmacology (Berl) VL - 178 IS - 1 SP - 92 EP - 99 AD - Department of Psychiatry and Neuropsychology (DRT10), Brain and Behavior Institute, Maastricht University, P.O. Box 616, Maastricht, 6200, The Netherlands. l.evers@np.unimaas.nl SN - 0033-3158 N2 - RATIONALE: Disorders associated with low levels of serotonin (5-HT) are characterized by mood and cognitive disturbances. Acute tryptophan depletion (ATD) is an established method for lowering 5-HT levels and an important tool to study the effects of reduced 5-HT on mood and cognition in human subjects. The traditional ATD method, i.e., administration of separate amino acids (AAs), has several disadvantages. The AA mixture is costly, unpalatable and associated with gastrointestinal discomfort. OBJECTIVES: The University of Maastricht developed a new and inexpensive method for ATD: a natural collagen protein (CP) mixture with low tryptophan (TRP) content. The reductions in plasma TRP after taking this CP mixture were compared with the reductions achieved taking the traditional AA mixture, and effects on memory and reversal learning were studied. METHODS: Fifteen healthy young volunteers participated in a double-blind, counterbalanced within-subject study. Reversal learning, verbal memory and pattern recognition were assessed at baseline and 3-4 h after taking the CP mixture. RESULTS: The new ATD method significantly reduced plasma TRP by 74% and the ratio between TRP and the other large AAs (TRP/LNAA) by 82%. The placebo mixture did not change these measures. Delayed recognition reaction time on the verbal learning task was increased following ATD. No other cognitive effects were found. CONCLUSIONS: The CP mixture was shown to be an efficient tool for lowering plasma TRP in humans. The validity of this method with regard to behavioral changes remains to be established in healthy, vulnerable and clinical populations. KW - tryptophan_depletion AU - Evers, EA AU - Tillie, DE AU - van der Veen, FM AU - Lieben, CK AU - Jolles, J AU - Deutz, NE AU - Schmitt, JA PY - 2005/02// UR - http://dx.doi.org/10.1007/s00213-004-2141-y ER -