Adults with a family history of alcohol related problems are more impulsive on measures of response initiation and response inhibition.

Background: Previous studies have found individuals with family histories of alcohol use disorders are more impulsive on some but not all laboratory behavioral measures, suggesting deficits on specific forms of impulse control. However, drawing conclusions is tenuous because these different measures have not been administered together in the same group of participants.

Methods: In the present study, we compared healthy 21-35 year old adults with family histories of alcohol related problems (FHAP+) or without such histories (FHAP-) on behavioral measures of response inhibition, response initiation, and consequence sensitivity impulsivity.

Failure to sustain prepulse inhibition in adolescent marijuana users.

Background: Marijuana use is typically initiated during adolescence, which is a critical period for neural development. Studies have reported reductions in prepulse inhibition (PPI) among adults who use marijuana chronically, although no human studies have been conducted during the critical adolescent period.

Methods: This study tested PPI of acoustic startle among adolescents who were either frequent marijuana users or naïve to the drug (Controls).

Specificity of the Acute Tryptophan and Tyrosine Plus Phenylalanine Depletion and Loading Tests Part II: Normalisation of the Tryptophan and the Tyrosine Plus Phenylalanine to Competing Amino Acid Ratios in a New Control Formulation.

Current formulations for acute tryptophan (Trp) or tyrosine (Tyr) plus phenylalanine (Phe) depletion and loading cause undesirable decreases in ratios of Trp or Tyr + Phe to competing amino acids (CAA), thus undermining the specificities of these tests. Branched-chain amino acids (BCAA) cause these unintended decreases, and lowering their content in a new balanced control formulation in the present study led to normalization of all ratios. Four groups (n = 12 each) of adults each received one of four 50 g control formulations, with 0% (traditional), 20%, 30%, or 40% less of the BCAA.

Specificity of the acute tryptophan and tyrosine plus phenylalanine depletion and loading tests I. Review of biochemical aspects and poor specificity of current amino Acid formulations.

The acute tryptophan or tyrosine plus phenylalanine depletion and loading tests are powerful tools for studying the roles of serotonin, dopamine and noradrenaline in normal subjects and those with behavioural disorders. The current amino acid formulations for these tests, however, are associated with undesirable decreases in ratios of tryptophan or tyrosine plus phenylalanine to competing amino acids resulting in loss of specificity. This could confound biochemical and behavioural findings.

Effects of acute tryptophan depletion on three different types of behavioral impulsivity.

Introduction: While central nervous system serotonin has been implicated in a variety of problematic impulsive behaviors, biological manipulation of brain serotonin using acute tryptophan depletion for studying changes in impulsive behavior has received little attention.

Methods: Using identical treatment conditions, we examined the effects of reduced serotonin synthesis for each of three matched groups using acute tryptophan depletion. Thirty healthy men and women (ages 18-45) were assigned to perform one of three tasks assessing different types of behavioral impulsivity: response initiation, response inhibition, and consequence sensitivity (N = 90).

Drinking histories in alcohol-use-disordered youth: preliminary findings on relationships to platelet serotonin transporter expression with genotypes of the serotonin transporter.

Objective: The serotonin (5-HT) transporter (5-HTT) is thought to play a key role in the onset of alcohol use, with potential behavioral and biological mechanisms mediated by the level of 5-HT in the synapse and in cerebral spinal fluid. Although 5-HT dysregulation has been related to poor impulse control, the biological mechanism is unknown, although functional control of the serotonergic system has been shown to be regulated in part by differential expression of the 5-HTT. The gene responsible for encoding 5-HTT has a functional polymorphism at the 5'-regulatory promoter region, which results in two forms: long (L) and short (S).

L-Tryptophan: Basic Metabolic Functions, Behavioral Research and Therapeutic Indications.

An essential component of the human diet, L-tryptophan is critical in a number of metabolic functions and has been widely used in numerous research and clinical trials. This review provides a brief overview of the role of L-tryptophan in protein synthesis and a number of other metabolic functions. With emphasis on L-tryptophan's role in synthesis of brain serotonin, details are provided on the research uses of L-tryptophan, particularly L-tryptophan depletion, and on clinical trials that have been conducted using L-tryptophan supplementation.