Midbrain-Driven Emotion and Reward Processing in Alcoholism

Alcohol dependence is associated with impaired control over emotionally motivated actions, possibly associated with abnormalities in the frontoparietal executive control network and midbrain nodes of the reward network associated with automatic attention. To identify differences in the neural response to alcohol-related word stimuli, 26 chronic alcoholics (ALC) and 26 healthy controls (CTL) performed an alcohol-emotion Stroop Match-to-Sample task during functional MR imaging. Stroop contrasts were modeled for color-word incongruency (eg, word RED printed in green) and for alcohol (eg, BEER), positive (eg, HAPPY) and negative (eg, MAD) emotional word content relative to congruent word conditions (eg, word RED printed in red). During color-Stroop processing, ALC and CTL showed similar left dorsolateral prefrontal activation, and CTL, but not ALC, deactivated posterior cingulate cortex/cuneus. An interaction revealed a dissociation between alcohol-word and color-word Stroop processing: ALC activated midbrain and parahippocampal regions more than CTL when processing alcohol-word relative to color-word conditions. In ALC, the midbrain region was also invoked by negative emotional Stroop words thereby showing significant overlap of this midbrain activation for alcohol-related and negative emotional processing. Enhanced midbrain activation to alcohol-related words suggests neuroadaptation of dopaminergic midbrain systems. We speculate that such tuning is normally associated with behavioral conditioning to optimize responses but here contributed to automatic bias to alcohol-related stimuli.     

Alcohol dependence and the alcohol Stroop paradigm: evidence and issues

AIMS: Firstly to test alcohol abusers attentional bias towards alcohol-related stimuli. Secondly, to shed light onto other factors that may influence the alcohol Stroop effect by considering variables including mood status in the analyses. Finally, to examine severity of dependence on Stroop performance. DESIGN: Repeated measures with alcohol versus control group as the between participant factors and within participant factors were the reaction times to different types of stimuli. Standard multiple regression was used to determine predictors of Stroop performance. A repeated measures design was used with severity of dependence as the between participant factors and Stroop reaction times as the within participant factors. SETTING: South and East London, UK. PARTICIPANTS: Sixty-four alcoholics in treatment and 64 community controls from general practice participated in the study. MEASUREMENTS: Alcohol dependence severity was measured using the SADQ, mood was measured with the POMS-SF and a computerised emotional Stroop task was employed to measure attentional bias. FINDINGS: Regardless of demographic factors and mood status, alcoholics responded significantly slower to alcohol-related than neutral words when compared to controls. When severity of alcohol dependence was used as between participant factors, no significant differences were found with Stroop performance between high and low alcohol severity groups. CONCLUSIONS: Alcohol-related stimuli are distracting to heavy users of alcohol, independent of demographic, mood and dependence status. Findings offer insight into the development of alcohol dependence and the issues that surround the alcohol Stroop paradigm.     

Alcohol attentional bias: drinking salience or cognitive impairment?

OBJECTIVE: This study evaluated whether alcohol attentional bias is an artifact of excessive drinkers' impaired cognitive functioning, which adversely affects their performance on the classic Stroop test (a measure of inhibitory control) and the Shipley Institute of Living Scale (SILS; a measure of verbal and abstraction ability). Both tests measure aspects of executive cognitive functioning (ECF). METHODS: Social drinkers (N=87) and alcohol-dependent drinkers (N=47) completed a measure of alcohol consumption, classic and alcohol-related Stroop tests, and the SILS. RESULTS: A multivariate analysis of variance (MANOVA) showed that the dependent drinkers were poorer on the cognitive measures (SILS scores and classic Stroop interference) and had greater alcohol attentional bias than the social drinkers. An analysis of covariance (ANCOVA) in which the cognitive measures were controlled showed that the dependent drinkers' greater alcohol attentional bias was not an artifact of their poorer cognitive performance. CONCLUSION: The results are discussed in terms of cognitive-motivational models, which suggest that excessive drinking sensitizes alcohol abusers' attentional responsiveness to alcohol-related stimuli to a degree that exceeds the adverse effects of alcohol on their general cognitive functioning.     

The priming effect of alcohol pre-load on attentional bias to alcohol-related stimuli

Background Previous research has shown attentional bias toward alcohol-related stimuli in non-dependent social drinkers. The aim of this study was to investigate whether attentional bias towards alcohol-related stimuli would increase after priming with either one of two doses of alcohol (0.3 or 0.6 g/kg) or placebo.Methods Questionnaires were used to measure alcohol use, mood states, craving for alcohol and alcohol outcome expectancies. Attentional bias was assessed using a dot-probe detection task and a modified Stroop task.Results Mood ratings showed dose dependent increases in positive mood after the alcohol pre-load. In the dot-probe task, all subjects showed an attentional bias towards the alcohol-related stimuli over neutral stationery-related items, although the attentional bias was significantly positive only at the low alcohol dose. In addition, a negative correlation was found between the attentional bias under the high alcohol dose and the alcohol use questionnaire score. In the Stroop task, a dose related effect of alcohol was found, with subjects making more errors for alcohol-related words under the high alcohol dose.Conclusions These data support ideas derived from the incentive learning theories of drug addiction. Furthermore, these data suggest that history of alcohol exposure may influence the priming effects of an alcohol pre-load on attentional bias.     

Alcohol attentional bias as a predictor of alcohol abusers' treatment outcome

Alcohol abusers' and non-abusers' attentional distraction for alcohol-related, concern-related, and neutral stimuli was assessed with the emotional Stroop paradigm. Alcohol abusers (n=14) were tested on admission to inpatient treatment and immediately before discharge, 4 weeks later; non-abusers (n=16) were also tested twice, with a 4-week intervening interval. Alcohol abusers were assessed for alcohol use 3 months after discharge. Unlike control participants and alcohol abusers whose treatment was successful, alcohol abusers whose treatment was unsuccessful (who relapsed or did not maintain post-discharge outpatient contact) had a significant increase in attentional distraction for alcohol stimuli during the 4 weeks of inpatient treatment. Compared to control participants and alcohol abusers who completed the 4 weeks of treatment, those who did not complete treatment (n=9) were highly distracted by concern-related stimuli at treatment admission. The results have implications for understanding the cognitive and motivational processes underlying successful treatment for alcohol abuse.     

Effects of acute alcohol consumption on alcohol-related cognitive biases in light and heavy drinkers are task-dependent

We investigated (1) the effects of alcohol on cognitive biases for alcohol-related cues, (2) the effects of drinking status on alcohol-related cognitive biases and (3) the similarity of any effects of alcohol across two measures of alcohol cognitive bias. Healthy, heavy and light social alcohol users (n = 72) were examined in a single-blind placebo-controlled design. Participants received 0.00 g/kg, 0.13 g/kg or 0.40 g/kg of alcohol in a between-subjects design and then completed both a modified Stroop task and a visual probe task. Modified Stroop data indicated a main effect of cue type, which was qualified by drinking status, with heavier drinkers slower to respond to alcohol-related cues. Visual probe data, in contrast, indicated a significant interaction effect between validity (valid: alcohol-related, invalid: neutral) and drink condition. Participants receiving a moderate dose of alcohol (0.40 g/kg) were faster to respond to alcohol-related stimuli compared with participants receiving a low dose of alcohol or placebo. These data indicate that the cognitive processes assayed by the visual probe and Stroop tasks may not be mediated by a common underlying mechanism.     

A consistent attentional bias for drug-related material in active cocaine users across word and picture versions of the emotional Stroop task

Evidence from a number of drug-abuse populations suggests that an attentional bias for drug-related stimuli can be identified in chronic users. Such an effect has yet to be reliably demonstrated in cocaine users, despite mounting evidence of the salience and reinforcing properties of cocaine-related cues. The aim of the current study was to administer word (modeled on the versions shown to successfully identify attentional biases in alcohol abusers) and picture versions of the emotional Stroop tasks to gauge the reliability of cocaine-specific attentional biases across stimuli domains. A comparison of active cocaine users (n = 23), and their age and education matched controls revealed a significant bias for cocaine-related pictures and words in users. This attentional bias could not be attributed to confounding factors such as slowed response speed of cocaine users, cocaine-related material sharing category ownership, or that the cocaine-related material used in the current study was generally arousing for all participants. A comparison of the different classes of stimuli indicated that cocaine users had a very similar level of difficulty controlling their attention towards both cocaine-related material and incongruent-colour word stimuli, the latter being the traditional measure of attentional control from the Stroop task. These results provide corroborating evidence for cognitive biases being a hallmark of substance dependence.     

Attention and recognition memory bias for alcohol-related stimuli among alcohol-dependent patients attending residential treatment

Though studies have examined attentional bias for alcohol-related information among alcohol-dependent individuals, few have examined memory bias. This study examined attention and recognition memory biases for alcohol-related information among patients recently admitted to residential alcohol treatment (n = 100; 40% female). Participants completed a computerized attentional task wherein they classified a centrally-presented digit as odd or even. On some trials, an alcohol word, neutral word, or anagram was presented along with the digit. On these dual trials participants first classified the digit and then classified the other stimulus as a word or nonword. Participants took longer to classify digits that appeared with alcohol words compared to neutral words; suggesting the alcohol words distracted them from processing the digit. In a subsequent recognition memory test, participants showed significantly higher hit rates (i.e., correctly classifying an old item as old) and false alarm rates (i.e., incorrectly classifying a new item as old) to the alcohol words compared to the neutral words, and they also showed a more liberal response bias to alcohol words. The findings suggest that alcohol-dependent individuals exhibit both attention and memory bias for alcohol-related information.     

Impact of positive and anxious mood on implicit alcohol-related cognitions in internally motivated undergraduate drinkers

We explored the impact of musically induced positive and anxious mood on the implicit alcohol-related cognitions of 48 undergraduate students who drink either to enhance positive mood states (EM) or to cope with anxiety (CM-anxiety). Participants completed a post-mood induction computerized alcohol Stroop task that taps implicit alcohol-related cognitions. As hypothesized, CM-anxiety participants in the anxious (but not those in the positive) mood condition showed longer colour-naming latencies for alcohol (vs. non-alcohol) targets (i.e., an attentional bias toward alcohol-related stimuli). Also conforming to expectation was the finding that EM participants in the positive (but not those in the anxious) mood condition displayed longer colour-naming latencies for (i.e., an attentional bias toward) alcohol (vs. non-alcohol) target words.     

A Combi-Stroop test for measuring food-related attentional bias

There are methodological complexities with the supraliminal-lexical versions of the modified versions of the Stroop tests that could be responsible for inconsistencies across the literature (Field & Cox, 2008). We tested whether a combination of subliminal-pictorial and classic Stroop tests can differentiate between dieters' and nondieters' food attentional bias (FAB). Participants were dieters (n = 30) and nondieters (n = 32) who were tested 3 hr after having a meal. Each picture from among 24 high-calorie and 24 low-calorie food pictures was presented for 32 ms before the appearance of a congruent or an incongruent color word, in response to which participants were required to manually report, via a tagged keyboard, the correct color of the word as quickly and accurately as possible. Color-naming latencies and interference scores were calculated. Dieters showed the highest reaction times to incongruent color words following high-calorie food pictures; overall, dieters showed significantly higher FABs than nondieters. The Combi-Stroop test has differential validity. Moreover, findings suggest that FAB can result from early allocation of dieters' attention to food-related stimuli.     

The effect of screening on prevalence estimates of alcohol dependence and social consequences

OBJECTIVE: Screener items are often used in surveys to identify individuals who are at high risk of experiencing alcohol dependence or alcohol-related problems. The purpose of this study is to determine the effect of two screener items (5 or more drinks ever and > or = 12 drinks last year) on prevalence estimates of alcohol dependence and negative social consequences. METHOD: The 1995 National Alcohol Survey data were analyzed. Differences in prevalence estimates between the unscreened current drinkers (n = 2,817) and the two screened samples: 5+ ever (n = 2,186) and > or = 12 drinks last year (n = 2,126) were compared. For each screened sample, prevalence estimates obtained from two base populations (screened positives only and all current drinkers assuming no alcohol-related problems among screened negatives) were examined. RESULTS: Comparisons of prevalence estimates of alcohol dependence and negative social consequences across the screened and unscreened samples revealed little bias in estimates with one exception. The only significant difference between the unscreened and screened samples was found among women when prevalence rates were obtained from data of screened positive respondents only. CONCLUSIONS: The effect of screening on national prevalence estimates of alcohol dependence and social consequences is small. Less bias in prevalence estimates is found when negatively screened light drinkers were assumed to report no alcohol-related problems rather than excluded from the estimation sample.     

fMRI BOLD response to alcohol stimuli in alcohol dependent young women

BACKGROUND: Cue reactivity in alcohol dependent adults has revealed autonomic, cognitive, and neural responses to alcohol-related stimuli that differ from those of nonabusers. Cue reactivity and craving responses have not been studied in youth. METHOD: Alcohol-dependent young women (n=8) and female light social drinkers (n=9) ages 18-24 were administered an alcohol cue reactivity task during functional magnetic resonance imaging (fMRI) to examine brain response to alcohol-related words. RESULTS: Alcohol dependent young women demonstrated significantly more blood oxygen level dependent (BOLD) response than nonabusers during alcohol word presentation trials relative to neutral word trials in subcallosal, anterior cingulate, left prefrontal, and bilateral insular regions (P<.025). However, controls showed greater response to alcohol words in some right hemisphere cortical regions. Increased craving after cue exposure correlated with increased subcallosal cortex BOLD response to alcohol cues (r=.87) among alcohol dependent subjects. CONCLUSIONS: This pilot study corroborates previous reports of increased limbic and frontal response to substance cues and extends these findings to young alcohol dependent women. This limbic reaction may underlie the elevated physiological response and altered cognitive reactions to alcohol stimuli that are observed in alcohol dependent individuals.     

Attentional bias associated with alcohol cues: differences between heavy and occasional social drinkers

RATIONALE: Previous research has shown an attentional bias toward drug-related stimuli in opiate addicts and toward emotionally threatening words in anxiety patients. OBJECTIVE: The primary aim of this study was to investigate whether non-dependent heavy social drinkers would differ in their selective attention towards alcohol-related stimuli in comparison with a group of occasional social drinkers. METHODS: Attentional bias was assessed using alcohol-related pictures and words in a dot probe detection task. Picture and word pairs were visually presented, followed by a dot probe that replaced one of the items. Attentional bias was determined from latencies in responding to the dot probe. Questionnaires were used to examine the relationships among attention, outcome expectancies after alcohol consumption, and personality traits. Higher-order executive function was also measured with two cognitive tasks, recognition memory and attentional shift. RESULTS: The heavy social drinkers showed an attentional bias towards the alcohol-related stimuli when compared to the occasional social drinkers. The heavy social drinkers also scored more highly on expectancy factors of sociability and sexuality and lower on the personality traits of self-directedness and persistence. Conclusion: The results support cognitive theories of addictive behaviour in which the ability of drug-related stimuli to capture attention is suggested to play a part in drug dependence, craving and relapse.     

Effects of alcohol cues on cognitive processing in heavy and light drinkers.

The effects of alcohol-related visual cues on cognitive processing in heavy and light social drinkers were assessed. Participants were exposed to either alcohol or control cues while they completed a cognitively demanding emotional Stroop task that used alcohol-related and control words as potential distracters. Heavy drinkers exposed to alcohol cues had significantly slower reaction times on the Stroop task than: (a) heavy drinkers exposed to control cues; and (b) light drinkers exposed to either alcohol or control cues. Results indicate that the effects of alcohol cues on automatic cognitive processes previously found in dependent drinkers' also occur in social drinkers. The magnitude of these effects varies directly with social drinkers' level of habitual alcohol use.     

Comparison of a population-based sample of "risky drinking" smokers and groups consuming just one substance

This population-based study compares a group of "risky drinking" smokers (n = 137) with groups of either smokers (n = 760) or "risky drinkers" (n = 173) regarding sociodemographic, behavioral and motivational variables. The study took place in a rural and urban region of Germany in 1997. No differences were found in sociodemographics, nicotine-related variables, frequency of alcohol consumption, and most alcohol-related diagnoses. People who drink and smoke show a higher proportion of alcohol dependence (ES: h = .20), drink more alcohol per occasion (ES: d = .39), and are more motivated to decrease alcohol consumption (ES: h = .45). The data suggest focusing research in more alcohol-related clinical settings and examining the relationship between smoking cessation and alcohol reduction.     

Examining fast and slow effects for alcohol and negative emotion in problem and social drinkers

Attentional bias (AB) for alcohol-related stimuli has been consistently demonstrated in social and problem drinkers. The aims of this study were to: investigate whether AB for alcohol-related stimuli could be described as a slow effect as well as a fast effect; how these effects relate to drinking behaviour; and the influence of the experimental procedure on priming effects. Two experiments were designed. In experiment 1, problem drinkers in treatment at a community alcohol service (N?=?62) and a group of social drinking controls (N?=?60) were assessed using the modified Stroop task with alcohol, negative emotion and neutral words. Drinking patterns were also recorded on the Khavari Alcohol Test. In experiment 2, social drinking controls (N?=?40) completed the same procedure but were blinded to the study’s aims. In experiment 1, both groups demonstrated slower response times to alcohol-related than neutral stimuli in both fast and slow processes. Difference scores for alcohol compared to neutral words in the slow process were positively correlated with increases in drinking levels for both groups. In experiment 2, AB to alcohol-related stimuli disappeared when participants were unprimed. The findings highlight the importance of investigating the role of fast and slow processes in continued and problem drinking, alongside priming effects from the experimental procedure.     

Alcohol-Related Words of Positive Affect are More Accessible in Social Drinkers' Memory Than are Other Words When Sip-Primed by Alcohol

Alcohol-related consequences of consumption with positive affect are claimed to be more accessible in memory than are negative, and to a limited extent this has been demonstrated with recall paradigms. This hypothesis is tested with a more robust recognition paradigm, the automated Stroop. A 3-factor mixed design was used: between subjects factor was Prime (soft or alcoholic drink); two within subjects factors were related to the Stroop word stimuli, Affect (positive or negative) and Alcohol-relatedness (related or unrelated). Sixty paid, volunteer, social drinkers took part. Binary colour choice RTs were measured and Stroop Interference RTs were derived in the standard way. Only correct RTs were analysed. Using a 2×2×2 ANOVA, a significant 3-way interaction was found (p=0.029). Words depicting positive consequences of alcohol consumption had significantly higher interference scores than did words depicting negative in the group primed with alcohol drink sips but not in the group primed with soft drink sips.     

A five-year prospective study of diagnostic orphans for alcohol use disorders

OBJECTIVE: One consequence of the DSM-IV diagnostic system for substance abuse and dependence is that there are individuals who might endorse one or two of the criterion items for dependence but not meet criteria for abuse. These persons have been referred to as "diagnostic orphans." The aim of the analyses presented here is to further understanding about this potentially important group. METHOD: The DSM-IV categorical approach was used to determine alcohol-related diagnoses for 439 young adult men. Structured face-to-face follow-up interviews were administered 5 years later. RESULTS: At the beginning of the evaluation period, 14.6% (n = 64) of the men were alcohol dependent, 18.2% (n = 80) fulfilled criteria for alcohol abuse, 16.4% (n = 72) did not meet criteria for an alcohol use disorder but endorsed one or two of the dependence criteria and 50.8% (n = 223) reported none of the dependence items. At the initial interview, and again 5 years later, the diagnostic orphans reported alcohol and drug use histories that fell between the histories of those with dependence and those with no alcohol-related difficulties. The orphans were most similar to the men with abuse, although they had lower quantities and frequencies of alcohol use, endorsed fewer additional alcohol-related problems and reported less involvement with drugs compared with that group. CONCLUSIONS: Although the diagnostic orphans were more similar to the subjects with alcohol abuse than they were to those with dependence or no diagnosis, the data do not necessarily support combining the orphans with those with abuse. These diagnostic orphans do, however, constitute an important group that carries an enhanced risk for alcohol use disorders and should be closely followed.     

Selective attention to smoking cues in former smokers

Repeated drug use modifies the emotional and cognitive processing of drug-associated cues. These changes are supposed to persist even after prolonged abstinence. Several studies demonstrated that smoking cues selectively attract the attention of smokers, but empirical evidence for such an attentional bias among successful quitters is inconclusive. Here, we investigated whether attentional biases persist after smoking cessation. Thirty-eight former smokers, 34 current smokers, and 29 non-smokers participated in a single experimental session. We used three measures of attentional bias for smoking stimuli: A visual probe task with short (500 ms) and long (2000 ms) picture stimulus durations, and a modified Stroop task with smoking-related and neutral words. Former smokers and current smokers, as compared to non-smokers, showed an attentional bias in visual orienting to smoking pictures in the 500 ms condition of the visual probe task. The Stroop interference index of smoking words was negatively related to nicotine dependence in current smokers. Former smokers and mildly dependent smokers, as compared to non-smokers, showed increased interference by smoking words in the Stroop task. Neither current nor former smokers showed an attentional bias in maintained attention (2000 ms visual probe task). In conclusion, even after prolonged abstinence smoking cues retain incentive salience in former smokers, who differed from non-smokers on two attentional bias indices. Attentional biases in former smokers operate mainly in early involuntary rather than in controlled processing, and may represent a vulnerability factor for relapse. Therefore, smoking cessation programs should strengthen self-control abilities to prevent relapses.     

Alcoholics' selective attention to alcohol stimuli: automated processing?

OBJECTIVE: This study investigated alcoholics' selective attention to alcohol words in a version of the Stroop color-naming task. METHOD: Alcoholic subjects (n = 23) and nonalcoholic control subjects (n = 23) identified the color of Stroop versions of alcohol, emotional, neutral and color words. Manual reaction times (RTs), skin conductance responses (SCRs) and heart rate (HR) were recorded. RESULTS: Alcoholics showed overall longer RTs than controls while both groups were slower in responding to the incongruent color words than to the other words. Alcoholics showed longer RTs to both alcohol (1522.7 milliseconds [ms]) and emotional words (1523.7 ms) than to neutral words (1450.8 ms) which suggests that the content of these words interfered with the ability to attend to the color of the words. There was also a negative correlation (r = -.41) between RT and response accuracy to alcohol words for the alcoholics, reflecting that the longer time the alcoholics used to respond to the color of the alcohol words, the more incorrect their responses were. The alcoholics also showed significantly greater SCRs to alcohol words (0.16 microSiemens) than to any of the other words (ranging from 0.04-0.08 microSiemens), probably reflecting the emotional significance of the alcohol words. Finally, the alcoholics evidenced smaller HR acceleration to alcohol (1.9 delta bpm) compared to neutral (2.8 delta bpm), which could be related to difficulties alcoholics experience in terminating their attention to the alcohol words. CONCLUSIONS: These findings indicate that it is difficult for alcoholics to regulate their attention to alcohol stimuli, suggesting that alcoholics' processing of alcohol information is automated.