Relationships between impulsivity and subjective response in an IV ethanol paradigm

Abstract

Rationale: Impulsivity and individual differences in subjective response to alcohol are risk factors for alcohol problems and possibly endophenotypes for alcohol dependence. Few prior studies have addressed relationships between the two constructs.

Objectives: To predict subjective responses to ethanol, we tested self-reported impulsiveness, ethanol dose condition (high dose, low dose, or placebo), and time (seven time points) along with interactions among these variables.

Methods: The present study is a secondary analysis of data from a within-subject, placebo-controlled, dose-ranging ethanol administration study using IV infusion with a clamping technique to maintain steady-state breath alcohol concentration. The sample consisted of healthy, non-alcohol dependent social alcohol drinkers between the ages of 21 and 30 (N=105). Participants at varying levels of impulsivity were compared with regard to stimulant and subjective responses to three ethanol dose conditions over time.

Results: Individuals with higher impulsivity reported elavated stimulant and dampened sedative response to alcohol, particularly at the higher dose. Higher impulsivity was associated with a steeper increase in stimulant effects during the first half of clamped ethanol infusion with the higher dose.

Conclusions: These results suggest that impulsive individuals may experience enhanced reinforcing, stimulant effects, and relatively muted aversive sedative effects from alcohol. These subjective responses may relate to enhanced risk of alcohol problems among more impulsive individuals.

Figure 1

Stimulant subjective response to IV ethanol by dose condition over time among participants at the lowest (1a) and highest (1b) quartile for self-reported impulsivity. Timepoints are with respect to the time at which steady state BrAC was first reached using a clamping procedure, which required approximately 20 minutes. Ethanol infusion occurred during the +10, +30 timepoints and +60 timepoints and ended after the +60 timepoint, which is indicated with a vertical line after the +60 timepoint. Equal spacing of timepoints was for parsimony and thus is not to scale.

Figure 2

Sedative subjective response to IV ethanol by dose condition over time among participants at the lowest (2a) and highest (2b) quartile for self-reported impulsivity. Timepoints are with respect to the time at which steady state BrAC was first reached using a clamping procedure, which required approximately 20 minutes. Ethanol infusion occurred during the +10 and +30 timepoints and +60 timepoints and ended after the +60 timepoint, which is indicated with a vertical line after the +60 timepoint. Equal spacing of timepoints was for parsimony and thus is not to scale.