Brain activation to cannabis- and alcohol-related words in alcohol use disorder

Changes of attentional bias in patients with alcohol use disorder during abstinence: A longitudinal study

BACKGROUND

Alcohol Use Disorder (AUD) is linked to an attentional bias towards alcohol-related cues (e.g. images, smells), which acquire incentive properties and promote continued consumption.

METHOD

We investigated how the general and alcohol attentional bias evolved longitudinally in AUD patients along two periods of abstinence: t = 0 (baseline, 1-3 months of abstinence) and t = 1 (follow-up; 6 months of abstinence), as well as their relationship with alcohol-related variables. General and alcohol-specific attentional bias were evaluated by the Classic and the Alcohol Stroop tests (neutral and alcohol conditions) in abstinent AUD patients and controls.

RESULTS

At t = 0, the AUD group exhibited both general and alcohol-specific attentional biases, with greater effect in the general bias. At t = 1, alcohol-specific attentional bias decreased specifically in the AUD group and reached control levels (with interference index levels increasing from 1-3 months to 6 months). However, general attentional bias showed a trend toward improvement but it did not significantly change through abstinence process (linear mixed models, controlling for age, BMI, sex and education).

CONCLUSIONS

In AUD patients, general and alcohol attentional biases exhibit different trajectories during abstinence, with the attentional bias toward alcohol improving significantly throughout this process whereas general attentional bias is maintained.

Does alcohol automatically capture drinkers' attention? Exploration through an eye-tracking saccadic choice task

RATIONALE

Dominant theoretical models postulate the presence of an automatic attentional bias (AB) towards alcohol-related stimuli in alcohol use disorder, such AB constituting a core feature of this disorder. An early alcohol AB has been documented in subclinical populations such as binge drinking (i.e., a drinking pattern prevalent in youth and characterized by repeated alternation between alcohol intoxications and withdrawals, generating cerebral consequences). However, the automatic nature of AB remains to be established.

OBJECTIVES

We investigated the automatic nature of AB in binge drinkers through the saccadic choice task. This eye-tracking paradigm consistently highlights the extremely fast and involuntary saccadic responses elicited by faces in humans, relative to other object categories. Through an alcohol-related adaptation of the saccadic choice task, we tested whether the early and automatic capture of attentional resources elicited by faces can also be found for alcohol-related stimuli in binge drinkers, as predicted by theoretical models.

METHODS

Forty-three binge drinkers and 44 control participants performed two versions of the saccadic choice task. In the original version, two images (a face, a vehicle) were displayed on the left and right side of the screen respectively. Participants had to perform a saccade as fast as possible towards the target stimulus (either face or vehicle). In the alcohol-related version, the task was identical, but the images were an alcoholic beverage and a non-alcoholic stimulus.

RESULTS

We replicated the automatic attraction towards faces in both groups, as faces generated higher saccadic accuracy, speed, and amplitude than vehicles, as well as higher corrective saccade proportion. Concerning the alcohol-related adaptation of the task, groups did not differ for the accuracy, speed, and amplitude of the first saccade towards alcohol. However, binge drinkers differed from controls regarding the proportion of corrective saccade towards non-alcoholic stimuli after an error saccade towards alcohol, suggesting the presence of an alcohol disengagement bias specific to binge drinkers.

CONCLUSIONS

Alcohol-related AB in binge drinkers is not characterized by an early and automatic hijacking of attention towards alcohol. This AB rather relies on later and more controlled processing stages, namely a difficulty to disengage attentional resources from alcohol-related stimuli.

Alcohol- and non-alcohol-related interference: An fMRI study of treatment-seeking adults with alcohol use disorder

BACKGROUND

Individuals with alcohol use disorder (AUD) have difficulty diverting attention away from alcohol-related stimuli and towards non-alcohol-related goals (i.e., alcohol-related attention interference). It remains unclear whether regulatory brain function differs during alcohol and non-alcohol-related interference. This study compares brain reactivity during the alcohol and classic Stroop and whether such brain function relates to AUD severity.

METHODS

46 participants with AUD completed alcohol and classic color-word Stroop tasks during fMRI. Brain activity was compared during alcohol and classic Stroop interference in the rostral and dorsal anterior cingulate cortices (rACC and dACC) and correlated with self-reported AUD severity. Exploratory whole-brain analyses were also conducted.

RESULTS

Behavioral interference (i.e., slower reaction times) was observed during alcohol and classic Stroop. rACC activity was significantly higher during the alcohol > neutral contrast versus the incongruent > congruent contrast. dACC activity did not differ between the Stroop tasks. dACC activity during incongruent > congruent was positively associated with AUD severity.

CONCLUSIONS

Activity in ACC subregions differed during alcohol and non-alcohol interference. Increased alcohol-related activity in the rACC, a region linked to emotional conflict resolution, suggests an interfering effect of self-relevant alcohol cues on non-alcohol-related processing. AUD severity was related to greater dACC reactivity during classic Stroop interference, suggesting that non-drug-related cognitive control impairments are more pronounced in those with more problematic alcohol use.

Attentional bias in alcohol drinkers: A systematic review of its link with consumption variables

In severe alcohol use disorder (SAUD), attentional bias refers to the preferential allocation of attentional resources toward alcohol-related cues. Dominant models consider that this bias plays a key role in the emergence and maintenance of SAUD. We evaluate the available experimental support for this assumption through a systematic literature review, providing a critical synthesis of studies exploring the links between alcohol consumption and attentional bias. Using PRISMA guidelines, we explored three databases (PsycINFO, PubMed, Scopus) and extracted 95 papers. We assessed their methodological quality and categorized them based on the population targeted, namely patients with SAUD or subclinical populations with various drinking patterns. We also classified papers according to the measures used (i.e., behavioral or eye-tracking measures). Overall, subclinical populations present an alcohol-related bias, but many studies in SAUD did not find such bias, nor approach/avoidance patterns. Moreover, attentional bias fluctuates alongside motivational states rather than according to alcohol use severity, which questions its stability. We provide recommendations to develop further theoretical knowledge and overcome methodological shortcomings.

Sex moderates effects of alcohol and cannabis co-use on alcohol and stress reactivity

BACKGROUND

Simultaneous or concurrent use (co-use) of alcohol and cannabis is associated with greater use of both substances over time, academic difficulties, more severe substance use consequences, and adverse impacts on cognitive functioning than the use of a single substance or no substance use. This study examined potential neural mechanisms underlying co-use behaviors in comparison to single substance use. Specifically, we compared alcohol cue reactivity and stress-cue reactivity among individuals who reported frequent same-day co-use of alcohol and cannabis and individuals who reported only alcohol use.

METHODS

The sample included 88 individuals (41 women) who reported only alcohol use and 24 individuals (8 women) who reported co-use of alcohol and cannabis on at least 50% of drinking occasions. All participants completed fMRI stress and alcohol cue reactivity tasks. Because of known sex effects on stress reactivity and alcohol cue reactivity, we tested sex by co-use interactions.

RESULTS

During alcohol cue presentation, co-users had less activation in the thalamus and dorsomedial prefrontal cortex than alcohol-only users, effects that were driven by differences in responses to neutral cues. Examination of stress cue reactivity revealed sex by co-use interactions in the lingual gyrus, with women co-users showing a greater difference between negative and neutral cue reactivity than all other groups. In addition, women co-users had greater connectivity between the nucleus accumbens and both the medial orbitofrontal cortex and the rostral anterior cingulate cortex during negative cue presentation than the other groups.

CONCLUSIONS

These results provide preliminary evidence of enhanced stress cue reactivity in individuals reporting co-use of alcohol and cannabis, particularly women co-users.

Towards quantifying the reciprocal associations between frequency of cannabis use and alcohol consumption: a cross-lagged analysis from the CONSTANCES cohort

OBJECTIVE

Disentangle the temporal relationships between frequency of cannabis use and alcohol consumption.

METHODS

A cross-lagged model providing standardised coefficients (SCs)±their standard errors in 13 255 men and 13 696 women enrolled in 2015 or 2016 in the French population-based 'CONSulTANts des Centres d'Examens de Santé' (CONSTANCES) cohort. Cannabis use was categorised as follows: 'No use during the past 12 months', 'Use during the past 12 months but not in the past month' and 'Use in the past month' for cannabis use at baseline, and No use during the past 12 months, 'Use less than once per month' and 'Use once per month or more' for cannabis use at 1 year of follow-up. Alcohol consumption was measured at baseline and at 1 year of follow-up and three categories were determined: low risk (<28 drinks per week in men; <14 drinks per week in women), moderate risk (≥28 and<42 in men; ≥14 and<28 in women) and high risk (≥42 in men; ≥28 in women). Analyses were adjusted for age, sex, education, income, tobacco consumption, self-rated health status and depressive symptoms.

RESULTS

Both associations from alcohol to cannabis and from cannabis to alcohol were significant (SC=0.02±0.01 with p=0.003 and SC=0.06±0.01 with p<0.001, respectively). However, the SC of the association from cannabis to alcohol was three times higher than the opposite association (p<0.001). After stratification for sex, SCs of the association from cannabis to alcohol were more than two times higher than for the opposite association in men, and more than four times higher in women (both p<0.001).

CONCLUSIONS

The association between frequency of cannabis use and subsequent alcohol consumption was stronger than the opposite association. This finding encourages considering the risk of increased alcohol consumption among cannabis users.

Acute depletion of dopamine precursors in the human brain: effects on functional connectivity and alcohol attentional bias

Individuals who abuse alcohol often show exaggerated attentional bias (AB) towards alcohol-related cues, which is thought to reflect reward conditioning processes. Rodent studies indicate that dopaminergic pathways play a key role in conditioned responses to reward- and alcohol-associated cues. However, investigation of the dopaminergic circuitry mediating this process in humans remains limited. We hypothesized that depletion of central dopamine levels in adult alcohol drinkers would attenuate AB and that these effects would be mediated by altered function in frontolimbic circuitry. Thirty-four male participants (22-38 years, including both social and heavy drinkers) underwent a two-session, placebo-controlled, double-blind dopamine precursor depletion procedure. At each visit, participants consumed either a balanced amino acid (control) beverage or an amino acid beverage lacking dopamine precursors (order counterbalanced), underwent resting-state fMRI, and completed behavioral testing on three AB tasks: an alcohol dot-probe task, an alcohol attentional blink task, and a task measuring AB to a reward-conditioned cue. Dopamine depletion significantly diminished AB in each behavioral task, with larger effects among subjects reporting higher levels of binge drinking. The depletion procedure significantly decreased resting-state functional connectivity among ventral tegmental area, striatum, amygdala, and prefrontal regions. Beverage-related AB decreases were mediated by decreases in functional connectivity between the fronto-insular cortex and striatum and, for alcohol AB only, between anterior cingulate cortex and amygdala. The results support a substantial role for dopamine in AB, and suggest specific dopamine-modulated functional connections between frontal, limbic, striatal, and brainstem regions mediate general reward AB versus alcohol AB.

Random Forest Classification of Alcohol Use Disorder Using EEG Source Functional Connectivity, Neuropsychological Functioning, and Impulsivity Measures

: Individuals with alcohol use disorder (AUD) manifest a variety of impairments that can be attributed to alterations in specific brain networks. The current study aims to identify features of EEG-based functional connectivity, neuropsychological performance, and impulsivity that can classify individuals with AUD (N = 30) from unaffected controls (CTL, N = 30) using random forest classification. The features included were: (i) EEG source functional connectivity (FC) of the default mode network (DMN) derived using eLORETA algorithm, (ii) neuropsychological scores from the Tower of London test (TOLT) and the visual span test (VST), and (iii) impulsivity factors from the Barratt impulsiveness scale (BIS). The random forest model achieved a classification accuracy of 80% and identified 29 FC connections (among 66 connections per frequency band), 3 neuropsychological variables from VST (total number of correctly performed trials in forward and backward sequences and average time for correct trials in forward sequence) and all four impulsivity scores (motor, non-planning, attentional, and total) as significantly contributing to classifying individuals as either AUD or CTL. Although there was a significant age difference between the groups, most of the top variables that contributed to the classification were not significantly correlated with age. The AUD group showed a predominant pattern of hyperconnectivity among 25 of 29 significant connections, indicating aberrant network functioning during resting state suggestive of neural hyperexcitability and impulsivity. Further, parahippocampal hyperconnectivity with other DMN regions was identified as a major hub region dysregulated in AUD (13 connections overall), possibly due to neural damage from chronic drinking, which may give rise to cognitive impairments, including memory deficits and blackouts. Furthermore, hypoconnectivity observed in four connections (prefrontal nodes connecting posterior right-hemispheric regions) may indicate a weaker or fractured prefrontal connectivity with other regions, which may be related to impaired higher cognitive functions. The AUD group also showed poorer memory performance on the VST task and increased impulsivity in all factors compared to controls. Features from all three domains had significant associations with one another. These results indicate that dysregulated neural connectivity across the DMN regions, especially relating to hyperconnected parahippocampal hub as well as hypoconnected prefrontal hub, may potentially represent neurophysiological biomarkers of AUD, while poor visual memory performance and heightened impulsivity may serve as cognitive-behavioral indices of AUD.

Random Forest Classification of Alcohol Use Disorder Using fMRI Functional Connectivity, Neuropsychological Functioning, and Impulsivity Measures

Individuals with alcohol use disorder (AUD) are known to manifest a variety of neurocognitive impairments that can be attributed to alterations in specific brain networks. The current study aims to identify specific features of brain connectivity, neuropsychological performance, and impulsivity traits that can classify adult males with AUD (n = 30) from healthy controls (CTL, n = 30) using the Random Forest (RF) classification method. The predictor variables were: (i) fMRI-based within-network functional connectivity (FC) of the Default Mode Network (DMN), (ii) neuropsychological scores from the Tower of London Test (TOLT), and the Visual Span Test (VST), and (iii) impulsivity factors from the Barratt Impulsiveness Scale (BIS). The RF model, with a classification accuracy of 76.67%, identified fourteen DMN connections, two neuropsychological variables (memory span and total correct scores of the forward condition of the VST), and all impulsivity factors as significantly important for classifying participants into either the AUD or CTL group. Specifically, the AUD group manifested hyperconnectivity across the bilateral anterior cingulate cortex and the prefrontal cortex as well as between the bilateral posterior cingulate cortex and the left inferior parietal lobule, while showing hypoconnectivity in long-range anterior-posterior and interhemispheric long-range connections. Individuals with AUD also showed poorer memory performance and increased impulsivity compared to CTL individuals. Furthermore, there were significant associations among FC, impulsivity, neuropsychological performance, and AUD status. These results confirm the previous findings that alterations in specific brain networks coupled with poor neuropsychological functioning and heightened impulsivity may characterize individuals with AUD, who can be efficiently identified using classification algorithms such as Random Forest.