An interoceptive basis for alcohol priming effects

Mapping acute alcohol effects on bodily sensations: A cross-dimensional interoceptive approach

BACKGROUND

Interoceptive processes may underlie maladaptive patterns of alcohol use. Bodily sensations experienced during alcohol intoxication could therefore reveal distinct mechanistic components relevant for addiction theory and research. Here, we apply novel tools to examine how intoxication impacts somatic awareness using bodily maps and a cardiac interoception task.

METHODS

In a double-blind, within-subjects, placebo-controlled study, social drinkers (n = 37, 17 female) were administered 0.4 g/kg of alcohol. We measured changes in self-reported bodily sensations during the ascending and descending limbs of the blood-alcohol curves using the emBODY tool. Additionally, we recorded biphasic measures of subjective alcohol effects (sedation and stimulation), changes in heart rate, and assessed psychophysical measures of cardiac beliefs using the heart rate discrimination task.

RESULTS

Acute alcohol administration altered bodily sensations, reflected by strong sensations in the chest, limbs, and head, with lesser effects in the placebo condition. Linear-mixed models examined correlates of bodily sensations across conditions. Extent of bodily sensations correlated with heart rate changes and breath alcohol content. In the ascending limb, bodily sensations negatively correlated with subjective stimulation and positively with sedation. Finally, extent of bodily sensations correlated with the metacognitive sensitivity of cardiac beliefs, suggesting a cross-dimensional integration between sensations and interoceptive awareness.

DISCUSSION

These findings highlight the value of bodily mapping in psychopharmacology, as interoceptive components of alcohol intoxication may provide a somatic basis for addiction. We interpret our results through low-sensitivity models, suggesting individuals with reduced bodily sensations during intoxication may face elevated risk for alcohol use disorder, a hypothesis that will be examined in future research.

Determinants of perceived pain relief from acute alcohol intake in a laboratory setting

Background

Studies of alcohol analgesia often assume that changes in pain sensitivity reflect the negative reinforcing effects of alcohol in pain self-management. However, factors that may influence perceived pain relief due to alcohol use remain incompletely characterized. Thus, the primary aim of this study was to identify which factors are most strongly related to self-reported pain relief in individuals with and without chronic pain after alcohol consumption.

Methods

This study combined data from two studies of alcohol analgesia in individuals who regularly consume alcohol with and without chronic pain. Alcohol analgesia expectancies were assessed during screening. In laboratory sessions, participants received an alcohol-containing (.08 g/dL target BrAC) or placebo beverage and rated subjective intoxication and subjective response (positive/negative aspects of stimulation/sedation). Participants underwent quantitative sensory testing to measure pain intensity, pain threshold, and relief. Paired sample t-tests determined effects of alcohol on pain measures. Hierarchical linear models determined factors associated with pain relief ratings in the alcohol condition.

Results

Pain relief and pain threshold were higher in the alcohol session relative to placebo, but pain intensity did not differ. In a 4-step hierarchical linear model, expectancy of pain relief, subjective intoxication, and high positive affect, but not pain threshold or pain intensity, were significantly and uniquely associated with perceived relief.

Conclusions

Taken together, results suggest the negative-reinforcing effects of alcohol for pain-management are not completely reflected by changes in pain sensitivity in a laboratory setting. Expectancies and subjective response may be important in determining an individual's evaluation of alcohol's efficacy for pain self-management.

Alcohol effects on interoception shape expectancies and subjective effects: a registered report using the heart rate discrimination task

AIMS

Alcohol acutely impacts interoceptive processes, which in turn affect the perception of alcohol effects and the development of alcohol expectancies. However, previous research is limited by the tools used to measure cardiac interoception and subjective alcohol effects. This registered report proposes a re-examination of previous findings using a state-of-the-art measure of interoceptive capacity, the heart rate discrimination task, and measurements of subjective alcohol effects across both ascending and descending limbs.

METHODS

In a double-blind, placebo-controlled experiment, n = 36 participants were given 0.4 g/kg of ethanol, and a baseline measure of alcohol expectancies was obtained. Changes in interoceptive capacity after beverage administration, along with measures of light-headedness, mood, and biphasic alcohol effects, were assessed over two sessions.

HYPOTHESES

As registered in this secondary data analysis, alcohol was expected to acutely impact different indices of interoceptive capacity, and those changes were hypothesized to correlate with subjective alcohol effects and expectancies. Analyses were conducted only following in-principle acceptance.

RESULTS

Alcohol-induced changes in interoceptive capacity predicted the development of light-headedness, stimulation, and negative mood. Changes in interoceptive capacity were also correlated with negative alcohol expectancies, as measured 2 weeks prior to the experiment. These effects were unique to the interoceptive condition, as null effects were observed in an exteroceptive control task.

DISCUSSION

This report offers a replication of key previous findings that alcohol impacts interoceptive processes to shape the detection of subjective alcohol effects. We propose that, through repeated drinking occasions, bodily responses feed into the experience of intoxication, shaping future expectancies about alcohol effects.

The impact of alcohol priming on craving and motivation to drink: a meta-analysis

BACKGROUND AND AIMS

An initial dose of alcohol can motivate-or prime-further drinking and may precipitate (re)lapse and bingeing. Lab-based studies have investigated the alcohol priming effect; however, heterogeneity in designs has resulted in some inconsistent findings. The aims of this meta-analysis were to (i) determine the pooled effect size for motivation to drink following priming, measured by alcohol consumption and craving, and (ii) examine whether design characteristics influenced any priming effect.

METHODS

Literature searches of PsycINFO, PubMed and Scopus in October 2020 (updated October 2021) identified lab-based alcohol priming studies that assessed effect of priming on motivation to drink. A tailored risk-of-bias tool assessed quality of lab-based studies. Random effects meta-analyses were computed on outcome data from 38 studies comparing the effect of a priming dose of alcohol against control on subsequent alcohol consumption/self-reported craving. Study characteristics that might have affected outcomes were design type (within/between-participant), dose of prime, time of motivation assessment, type of control drink (placebo alcohol/soft drink).

RESULTS

Relative to control, alcohol had a small-to-moderate priming effect on subsequent alcohol consumption (standardised mean difference [SMD] = 0.336 [95% CI, 0.171, 0.500]) and craving (SMD = 0.431 [95% CI, 0.306, 0.555]). Aspects of study design differentially affected consumption and craving. The size of the priming dose had no effect on consumption, but larger doses were sometimes associated with greater craving (with craving generally following the blood alcohol curve). Alcohol priming effects for consumption, but not craving, were smaller when compared with placebo, relative to soft drink, control.

CONCLUSIONS

Lab-based alcohol priming studies are a valid paradigm from which to investigate the impact of acute intoxication on alcohol motivation. Designs are needed that assess the impact of acute consumption on motivation to drink in more varied and realistic ways.

Interoception and alcohol: Mechanisms, networks, and implications

Interoception refers to the perception of the internal state of the body and is increasingly being recognized as an important factor in mental health disorders. Drugs of abuse produce powerful interoceptive states that are upstream of behaviors that drive and influence drug intake, and addiction pathology is impacted by interoceptive processes. The goal of the present review is to discuss interoceptive processes related to alcohol. We will cover physiological responses to alcohol, how interoceptive states can impact drinking, and the recruitment of brain networks as informed by clinical research. We also review the molecular and brain circuitry mechanisms of alcohol interoceptive effects as informed by preclinical studies. Finally, we will discuss emerging treatments with consideration of interoception processes. As our understanding of the role of interoception in drug and alcohol use grows, we suggest that the convergence of information provided by clinical and preclinical studies will be increasingly important. Given the complexity of interoceptive processing and the multitude of brain regions involved, an overarching network-based framework can provide context for how focused manipulations modulate interoceptive processing as a whole. In turn, preclinical studies can systematically determine the roles of individual nodes and their molecular underpinnings in a given network, potentially suggesting new therapeutic targets and directions. As interoceptive processing drives and influences motivation, emotion, and subsequent behavior, consideration of interoception is important for our understanding of processes that drive ongoing drinking and relapse.

Does alcohol affect emotional face processing via interoceptive pathways?

BACKGROUND

Our brain uses interoceptive signals from the body to shape how we perceive emotions in others; however, whether interoceptive signals can be manipulated to alter emotional perceptions is unknown. Alcohol has acute effects both on emotional processing and on the physiological substrates supporting interoception. In this registered report, we examine whether alcohol administration triggers physiological changes that alter interoceptive signals and manipulate emotional face processing. Such knowledge will broaden understanding of the mechanisms by which alcohol affects emotional face processing.

METHODS

Participants (n = 36) will be administered an alcohol or placebo beverage. Cardiovascular physiology will be recorded before and after administration. Participants will complete two behavioral tasks in which they view emotional faces presented in synchrony with different phases of the cardiac cycle (i.e., systole, diastole). This manipulation creates an index of how interoceptive signals amplify emotional face processing.

HYPOTHESES

We hypothesize that, compared to placebo, alcohol administration will disrupt the cardiac amplification of emotional face processing. We further explore whether this disruption depends on the nature and magnitude of changes in cardiovascular physiology after alcohol administration.