Neural correlates of alcohol use disorder severity among nontreatment-seeking heavy drinkers: An examination of the incentive salience and negative emotionality domains of the alcohol and addiction research domain criteria

BACKGROUND

The Alcohol and Addiction Research Domain Criteria (AARDoC) propose that alcohol use disorder is associated with neural dysfunction in three primary domains: incentive salience, negative emotionality, and executive function. Prior studies in heavy drinking samples have examined brain activation changes associated with alcohol and negative affect cues, representing the incentive salience and negative emotionality domains, respectively. Yet studies examining such cue-induced changes in functional connectivity (FC) are relatively sparse.

METHODS

Nontreatment-seeking heavy drinking adults (N = 149, 56.0% male, 48.6% non-white, mean age 34.8 years (SD = 10.0)) underwent functional magnetic resonance imaging during presentation of alcohol, negative, and neutral pictures. We focused on FC changes involving the nucleus accumbens and amygdala in addition to activation and FC correlations with self-reported AUD severity.

RESULTS

For alcohol cues versus neutral cues, we observed accumbens FC changes in the cerebellum and prefrontal cortex (PFC), and amygdala FC changes with occipital, parietal, and hippocampal regions. AUD severity correlated positively with activation in the cerebellum (p < 0.05), accumbens FC in the cingulate gyri, somatosensory gyri, and cerebellum (p < 0.05), and with amygdala FC in the PFC and inferior parietal lobule (p < 0.05) for alcohol cues versus neutral cues. For negative cues versus neutral cues, we observed accumbens FC changes in the lateral temporal, occipital, and parietal regions, and amygdala FC changes in the fusiform and lingual gyri (p < 0.05).

CONCLUSIONS

The present findings provide empirical support for the AARDoC domains of incentive salience and negative emotionality and indicate that AUD severity is associated with salience and response control for reward cues. When covarying for differences in nonalcohol substance use and mood disorder diagnoses, AUD severity was also associated with emotional reactivity for negative cues.

Differences Between Treatment-Seeking and Nontreatment-Seeking Alcohol-Dependent Research Participants: An Exploratory Analysis

BACKGROUND

Alcoholism is a chronic relapsing disorder with complex behavioral and functional heterogeneity. To date, attempts to characterize subgroups of alcohol-dependent (AD) individuals have largely been focused on categorical distinctions based on behaviors such as ability to abstain, age of onset, and drinking motives, but these have failed to yield predictors of treatment response and disease course. The distinction between AD individuals who are or are not interested in treatment holds significant implications for interpreting results of human laboratory studies with nontreatment seekers and clinical trials with treatment-seeking AD patients. However, despite their crucial role in alcohol-related research, these 2 groups are poorly defined. In this exploratory analysis, we attempt to better define the phenotypic differences between these 2 experimentally relevant populations.

METHODS

We analyzed data from AD individuals who participated in screening protocols to evaluate their suitability for participation in either treatment or nontreatment research studies at NIAAA. Scores on individual measures from a battery of behavioral, neuropsychological, and blood laboratory measures were compared between those who presented seeking treatment for AD and those who were not seeking treatment. Differences in each measure were assessed between the 2 groups. In addition, we explored whether significant differences were apparent when drinking behavior was used as a covariate.

RESULTS

Treatment seekers manifested more impairment compared to nontreatment seekers on a wide variety of measures in the following categories: alcohol drinking, personality, impulsivity, trauma/stress, cognition, aggression, mood, and liver enzyme tests. Treatment seekers endorsed a greater number of AD criteria. Several measures including elevations in liver enzyme tests remained significantly different between the 2 groups when average daily alcohol consumption per drinking day was used as a covariate.

CONCLUSIONS

Treatment-seeking, compared to nontreatment-seeking AD subjects who present for alcohol-related research studies, differ in characteristics beyond the quantity of alcohol consumption. Implications of these differences with respect to clinical research for treatments of AD are discussed.

Associations Between Recent Heavy Drinking and Dorsal Anterior Cingulate N-Acetylaspartate and Glutamate Concentrations in Non-Treatment-Seeking Individuals with Alcohol Dependence

BACKGROUND

Proton magnetic resonance spectroscopy ((1) H-MRS) studies have consistently found abnormal brain concentrations of N-acetylaspartate (NAA) and glutamate in individuals with alcohol use disorders (AUD) relative to light drinkers. However, most such studies have focused on individuals in treatment for severe alcohol dependence (AD), and few studies have investigated associations between neurochemical concentrations and recent alcohol consumption. This study focused on associations between recent drinking and prefrontal neurometabolite concentrations in nonsevere, non-treatment-seeking individuals with AUD.

METHODS

Nineteen treatment-naïve alcohol-dependent individuals aged 21 to 40 completed a (1) H-MRS scan. Single-voxel (1) H-MRS spectra were acquired in dorsal anterior cingulate cortex (dACC) using a 2-dimensional J-resolved point resolved spectroscopy sequence. Associations between recent heavy drinking, assessed using the Timeline FollowBack, and dACC metabolite concentrations were estimated via regression controlling for within-voxel tissue composition.

RESULTS

Participants provided a negative breathalyzer reading and reported between 1 and 5 days (M = 2.45, SD = 1.23) since their last drink. Number of heavy drinking days in the 14 days preceding the scan (M = 4.84, SD = 3.32) was significantly inversely associated with both glutamate/water (β = -0.63, t(17) = -3.37, p = 0.004) and NAA/water concentrations (β = -0.59, t(17) = -2.98, p = 0.008).

CONCLUSIONS

This study extends the literature by demonstrating inverse associations between recent heavy drinking and dACC glutamate and NAA concentrations in a sample of nonsevere, non-treatment-seeking individuals with AD. These findings may support the hypothesis that amount of recent alcohol consumption may account for differences in neuronal metabolism, even in nonsevere, non-treatment-seeking alcoholics.