The effects of alcohol on laboratory-measured impulsivity after l-Tryptophan depletion or loading

Abstract

These findings demonstrate that reduced serotonin synthesis can produce increased impulsivity even among non-impulsive normal controls, and that the behavioral effects of alcohol are, in part, dependent on this biological state.

Effects of acute tryptophan depletion on memory, attention and executive functions: A systematic review

“…Three studies reported no effect of ATD on CPT performance in healthy adults or participants classified as highneuroticism individuals (Harrison et al, 2004;Park et al, 1994;Stewart et al, 2002). In contrast, Dougherty et al (2007) showed that ATD increased commission errors relative to TRP loading and Walderhaug et al (2002) reported that ATD led to a more lenient response criterion for number targets and caused fewer hits and decreased perceptual sensitivity for shape targets during a modified CPT. Similar findings were later reported by the same group (Walderhaug et al, 2008) but only when the task was novel.…”

“…Given that the plasma TRP to large neutral amino acid ratio is believed to be a more accurate measure of TRP levels in the brain (Fernstrom, 1979), these studies that found large increases in plasma TRP following the balanced drink cannot be definitively considered to be TRP loading. Rubia et al (2005) 100 g AA mixture, 2.3 g TRP # 80% a " 63% a Not assessed Not assessed Allen et al (2006) 100 g AA mixture, 2.3 g TRP # 79% a " 71% a Not assessed Not assessed Amin et al (2006) AA mixture, composition not specified # 84% " 123% Not assessed Not assessed Evers et al (2006a) 75 g AA mixture, 3.0 g TRP # 80% a " 202% a # 91% " 17% Evers et al (2006b) 75 g AA mixture, 3.0 g TRP # 59% a " 128% a # 77% " 15% Marsh et al (2006) 31.5 g AA in capsules, # 80% # 38% Not reported Not reported 31 g lactose (balanced drink) b Munafo et al (2006) 31 g AA mixture, 2.0 g TRP b Not reported Not reported Not assessed Not assessed Roiser et al (2006) 75 g AA mixture, 3.0 g TRP d # 69% a " 65% a # 63% " 36% Scholtissen et al (2006) 75 g AA mixture, 3.0 g TRP # 58% Not reported # 75% " 39% Talbot et al (2006) 105 g AA mixture, 2.2 g TRP b, d # 71% " 66% Not assessed Not assessed van der Veen et al (2006) 75 g AA mixture, 3.0 g TRP # 62% a " 131% a # 80% " 10% Dougherty et al (2007) 50 g AA mixture, 5.15 g TRP c # 76% a Not applicable # 83% Not applicable " 237% a,c " 127% c Epperson et al (2007) ? Task -identical pairs When task was novel, increased false alarms in number and shape modes, lowered response criterion in number mode, and decreased perceptual sensitivity in shape mode Crossover design Harrison et al (2002) 13 healthy volunteers 13F (22) Inspection time with backward masking…”

“…Three studies intentionally included a TRP loading condition (Burgund et al, 2003;Dougherty et al, 2007;Luciana et al, 2001). The reduction in plasma TRP levels following ATD varied from as low as 46% (Kulz et al, 2007) to as high as 97% (Harrison et al, 2002(Harrison et al, , 2004.…”

Comparison of 50- and 100-g l-tryptophan depletion and loading formulations for altering 5-HT synthesis: pharmacokinetics, side effects, and mood states

“…As Trp manipulations have typically been used to test a particular outcome (e.g., mood or behavior) at a single time point, the contribution of the current study is to compare a complete 7-h plasma time course, along with mood states and somatic side effects, after administration of the 50-and 100-g depletion and loading formulations. While the loading formulation is less commonly used than the balanced control, there are some studies that have elected to use loading as a comparison to depletion (e.g., Bjork et al 1999Bjork et al , 2000Cleare and Bond 1995;Dougherty et al 2007;Luciana et al 2001;Pihl et al 1995;Riedel et al 2003), and at least one (Luciana et al 2001) has found that the loading formulation resulted in negative cognitive outcomes, while the depletion formulation did not.…”

Serotonin Depletion Impairs Waiting but not Stop-Signal Reaction Time in Rats: Implications for Theories of the Role of 5-HT in Behavioral Inhibition

“…Indeed, 5-HT function is linked with the modulation of impulsive action on many of these tests. For example, premature response control ('waiting') on the rat 5-CSRT task and human CPT is influenced by 5-HT receptor manipulations and central 5-HT depletion (Carli et al, 2006;Carli and Samanin, 2000;Dougherty et al, 2007;Harrison et al, 1997;Robinson et al, 2007;Walderhaug et al, 2002Walderhaug et al, , 2008. Furthermore, 5-HT depletion also impaired go/no-go inhibition in rats and hostile aggressive children with ADHD (Harrison et al, 1999;Masaki et al, 2006;Zepf et al, 2008).…”