The Brugmann Fatigue Scale: An Analogue to the Epworth Sleepiness Scale to Measure Behavioral Rest Propensity.

Background: While often confused, fatigue (as opposed to sleepiness) mostly requires rest, not sleep, to recover from. Clinical evaluations of fatigue mainly rely on assessments of symptom intensity, however without taking into account the need to engage in behavioral countermeasures. We therefore developed an 8-item 4-point Likert scale (the Brugmann Fatigue Scale; BFS) sharing a similar conceptual background with the Epworth Sleepiness Scale (ESS), assessing mental and physical fatigue and focusing specifically on rest propensity. Methods: Out of 496 consecutive patients addressed to the sleep unit of an academic hospital, we selected a sample of 295 hypnotic-free subjects (122 females). The present study examines (a) the psychometric properties of the BFS and (b) measurement invariance regarding perceived sleep quality, in parallel with common sleepiness and fatigue scales (ESS and Fatigue Severity Scale; FSS). In addition, (c) correlations of the BFS with clinical scales and polysomnographic variables were explored descriptively. Results: Rasch analyses revealed that the BFS possesses sound psychometric characteristics (rating scale functioning, item fit, dimensionality and measurement invariance) allowing for valid, reliable, linear and unidimensional measurement of mental and physical rest propensity, irrespective of perceived sleep quality, age, or gender. In addition, the BFS was significantly correlated to periodic limb movements during sleep and inversely to REM sleep duration. For both mental and physical subscales, scores above 6 are proposed as cutoff values. Conclusion: In analogy to the ESS, the BFS shows to be a unique and precise instrument assessing symptomatic fatigue with respect to rest propensity.

The impact of self-control cues on subsequent monetary risk-taking.

BACKGROUND AND AIMS: The "process-model" of self-control proposes that the ego-depletion effect is better explained by a switch between interest in "have-to" labor and cognitive "want-to" leisure, rather than being mainly due to a decrease in cognitive resources, as advanced by the "strength-model" of self-control. However, it is currently difficult to disentangle the "process-model" from the "strength-model" of self-control. Here, we employed a stepwise approach, featuring three studies, for testing the process model of self-control. METHODS: In Study 1, we created a list of 30 self-control events for characterizing "have-to" conducts in the daily life. In Study 2, mental visualization of effortful self-control events ("have-to") and monetary risk-taking ("want-to") were employed for testing the strength-model of self-control. In Study 3, to test the process-model of self-control, participants were simply required to read self-control (or neutral) sentences. RESULTS: Study 1 provided evidence regarding external validly for the list of self-control events. Study 2 showed that mental visualization of effortful self-control events increases subsequent monetary risk-taking. Study 3 highlighted that the brief apparition of a self-control-related sentence was sufficient for increasing risk-taking. These patterns were evidenced in the trial with the less advantageous gain/loss ratio. DISCUSSION: Altogether these findings support the process-model of self-control in showing that triggering the semantic content of a "have-to" conduct, without its actual execution, is sufficient for modulating subsequent "want-to" activity. CONCLUSION: These findings could contribute to advancing current knowledge on how the high availability of ready-to-consume rewards in modern environments is redefining humans' self-control ability.

Short-Term Impact of tDCS Over the Right Inferior Frontal Cortex on Impulsive Responses in a Go/No-go Task.

Inhibitory control, a process deeply studied in laboratory settings, refers to the ability to inhibit an action once it has been initiated. A common way to process data in such tasks is to take the mean response time (RT) and error rate per participant. However, such an analysis ignores the strong dependency between spontaneous RT variations and error rate. Conditional accuracy function (CAF) is of particular interest, as by plotting the probability of a response to be correct as a function of its latency, it provides a means for studying the strength of impulsive responses associated with a higher frequency of fast response errors. This procedure was applied to a recent set of data in which the right inferior frontal gyrus (rIFG) was modulated using transcranial direct current stimulation (tDCS). Healthy participants (n = 40) were presented with a "Go/No-go" task (click on letter M, not on letter W, session 1). Then, one subgroup (n = 20) was randomly assigned to one 20-minutes neuromodulation session with tDCS (anodal electrode, rIFG; cathodal electrode, neck); and the other group (n = 20) to a condition with sham (placebo) tDCS. All participants were finally confronted to the same "Go/No-go" task (session 2). The rate of commission errors (click on W) and speed of response to Go trials were similar between sessions 1 and 2 in both neuromodulation groups. However, CAF showed that active tDCS over rIFG leads to a reduction of the drop in accuracy for fast responses (suggesting less impulsivity and greater inhibitory efficiency), this effect being only visible for the first experimental block following tDCS stimulation. Overall, the present data indicate that boosting the rIFG may be useful to enhance inhibitory skills, but that CAF could be of the greatest relevance to monitor the temporal dynamics of the neuromodulation effect.

Proactive and Reactive Motor Inhibition in Top Athletes Versus Nonathletes.

We examined proactive (early restraint in preparation for stopping) and reactive (late correction to stop ongoing action) motor response inhibition in two groups of participants: professional athletes ( n = 28) and nonathletes ( n = 25). We recruited the elite athletes from Belgian national taekwondo and fencing teams. We estimated proactive and reactive inhibition with a modified version of the stop-signal task (SST) in which participants inhibited categorizing left/right arrows. The probability of the stop signal was manipulated across blocks of trials by providing probability cues from the background computer screen color (green = 0%, yellow =17%, orange = 25%, red = 33%). Participants performed two sessions of the SST, where proactive inhibition was operationalized with increased go-signal reaction time as a function of increased stop-signal probability and reactive inhibition was indicated by stop-signal reaction time latency. Athletes exhibited higher reactive inhibition performance than nonathletes. In addition, athletes exhibited higher proactive inhibition than nonathletes in Session 1 (but not Session 2) of the SST. As top-level athletes exhibited heightened reactive inhibition and were faster to reach and maintain consistent proactive motor response inhibition, these results confirm an evaluative process that can discriminate elite athleticism through a fine-grained analysis of inhibitory control.

Implementation Intention for Initiating Intuitive Eating and Active Embodiment in Obese Patients Using a Smartphone Application.

This article describes a study protocol, which aims to explore and describe the feasibility of a mobile-phone application for initiating intuitive eating and intuitive exercising in patients who are following an ambulatory treatment for obesity. Intuitive eating refers to one's ability to make food choices based on one's awareness of his/her body's response. Intuitive exercising encourages people in finding enjoyable ways of being physically active. These two components will be trained using an implementation intention procedure, that is, behavioral plans that aim at creating a strong link between a specified situation and a response. We aim to recruit up to 80 overweight and obese patients over a period of 2 years. The smartphone application will be assessed on the basis of (i) data obtained through a 4-week use period, (ii) self-report measures taken before and after the use of the mobile application, and (iii) feedbacks from participants after the use of the mobile application. This pilot study will allow us to better understand the applicability of the use of mobile application within ambulatory treatment settings, and to adapt the design of the app necessary for building cross-sectional studies investigating its efficacy.

Examination of the validity and reliability of the French version of the Brief Self-Control Scale.

This study aims to develop and to validate a French version of the Brief Self-Control Scale (BSCS; Tangney et al., 2004). This instrument is usually applied as a unidimensional self-report measure for assessing trait self-control, which captures one's dispositional ability to resist short-term temptation in order to reach more valuable long-term goals. Data were collected from two independent samples of French-speaking individuals (n1 = 287; n2 = 160). Results indicated that the French version of the BSCS can be treated as unidimensional, like the original questionnaire. Data also showed consistent acceptable reliability and reasonable test-retest stability. Acceptable external validity of constructs was supported by relationships with self-reported measures of impulsivity (UPPS), including urgency, lack of premeditation, and lack of perseverance. Overall, the findings suggest that the average score of the French version of the BSCS is a viable option for assessing trait self-control in French speaking populations.

Changes in Pro-Inflammatory Markers in Detoxifying Chronic Alcohol Abusers, Divided by Lesch Typology, Reflect Cognitive Dysfunction.

AIM: To investigate pro-inflammatory markers in the blood and associate with cognitive impairment. METHODS: Il-6 and ferritin were assayed in the blood of 27 patients, divided according to Lesch typology, at the commencement and after 21 days of detoxification, together with a battery of cognitive tests. RESULTS: A significantly higher mean level of IL-6 was present in the blood of patients with Lesch typology 1 compared to the other typologies 2 and 3 on admission to the Detoxification Ward which did not alter significantly after detoxification. The mean level of IL-6 was initially elevated in Lesch typology 2 alcohol abusers and declined to the reference range after detoxification. Lesch typology 3 alcohol abusers showed normal levels of IL-6 at both time points. Only in Lesch typology 1 were the levels of ferritin and IL-10 significantly elevated at the start of the detoxification process. Cognitive impairment, as ascertained by Stroop test and Brown-Peterson procedure was greater in Lesch typology 1 than the other 2 patient groups. CONCLUSION: Such data might indicate a greater degree of neuroinflammation in Lesch typology 1 alcoholic patients. SHORT SUMMARY: Dividing a heterogeneous group of alcoholic subjects into homogenous groups according to Lesch typology, identifies a greater pro-inflammatory profile in Lesch typology 1 patients who also showed greater cognitive impairment.

Conditional Reasoning in Schizophrenic Patients.

Conditional reasoning (if p then q) is used very frequently in everyday situations. Conditional reasoning is impaired in brain-lesion patients, psychopathy, alcoholism, and polydrug dependence. Many neurocognitive deficits have also been described in schizophrenia. We assessed conditional reasoning in 25 patients with schizophrenia, 25 depressive patients, and 25 controls, using the Wason selection task in three different domains: social contracts, precautionary rules, and descriptive rules. Control measures included depression, anxiety, and severity of schizophrenia measures as a Verbal Intelligence Scale. Patients with schizophrenia were significantly impaired on all conditional reasoning tasks compared to depressives and controls. However, the social contract and precautions tasks yielded better results than the descriptive tasks. Differences between groups disappeared for social contract but remained for precautions and descriptive tasks when verbal intelligence was used as a covariate. These results suggest that domain-specific reasoning mechanisms, proposed by evolutionary psychologists, are relatively resilient in the face of brain network disruptions that impair more general reasoning abilities. Nevertheless, patients with schizophrenia could encounter difficulties understanding precaution rules and social contracts in real-life situations resulting in unwise risk-taking and misunderstandings in the social world.

A smoking-related background helps moderate smokers to focus: An event-related potential study using a Go-NoGo task.

OBJECTIVE: Cognitive impairment is a major component in addiction. However, research has been inconclusive as to whether this is also the case for smokers. The present study aims at providing electrophysiological clue for altered inhibitory control in smokers and at investigating whether reduced inhibition was more pronounced during exposure to a smoking cue. METHODS: ERPs were recorded during a visual Go-NoGo task performed by 18 smokers and 23 controls, in which either a frequent Go signal (letter "M") or a rare No-Go signal ("letter W") were superimposed on three different long-lasting background contexts: black-neutral, smoking-related and non smoking-related. RESULTS: (1) Smokers performed worse and had an earlier NoGo-N2 latency as compared to controls and independently of context, suggesting a general inhibition impairment; (2) with smoking-related backgrounds specifically, smokers made fewer mistakes than they did in other contexts and displayed a larger NoGo P3 amplitude. CONCLUSION: These data might suggest that background cues related to addiction may help smokers to be more accurate in an inhibition task. SIGNIFICANCE: Our results show the classical inhibitory impairment in smokers as compared to non-smokers. However, our data also suggest that a smoking-related background may bolster the inhibitory ability of smokers specifically.

Smoking addiction: the shift from head to hands: Approach bias towards smoking-related cues in low-dependent versus dependent smokers.

The dual process theory is central to several models of addiction, implying both an increase of stimulus salience and deficits in inhibitory control. Our major aim is to provide behavioral evidence for an approach bias tendency in smokers and more specifically during smoking cue exposure. The second aim is to examine whether this bias differs in low-dependent versus dependent smokers. Thirty-two smokers (17 low dependent and 15 dependent; cut-off FTND of 4) and 28 non-smokers performed a modified Go/NoGo task using tobacco-related words and neutral words as stimuli. Smokers generally made more mistakes and tended to be faster for smoking-related cues specifically. Low dependents acknowledged more their dependency in declarative questionnaires while making more errors and being slower specifically on smoking cues; dependent smokers were less prone to indicate their addiction, but were faster and accurate when it came to picking the smoking cues. These results suggest that a shift has operated from a mental preoccupation with smoking in the low-dependent group, to smoking as a motor habit in our dependent group. This finding invites experts to rethink smoking addiction in the light of this crucial moment, namely, the shift "from head to hands".

While Isolated Periodic Limb Movement Disorder Significantly Impacts Sleep Depth and Efficiency, Co-Morbid Restless Leg Syndrome Mainly Exacerbates Perceived Sleep Quality.

BACKGROUND: Restless leg syndrome (RLS) and periodic limb movement (PLM) disorder (PLMD) can affect sleep quality and interfere with daytime functioning. Whether the co-morbidity of RLS further worsens daytime symptoms, sleep architecture and quality in patients with PLMs, is not yet fully clarified. METHODS: Sleep (polysomnography) and daytime symptoms of 47 drug-free patients, assigned to isolated PLMD or co-morbid RLS subgroups, were compared to controls in a retrospective cohort-study (n = 501). Associations between perceived sleep quality, fatigue, sleepiness, mood and sleep variables were explored descriptively. RESULTS: Although co-morbid patients showed worsened sleep quality, both patient groups showed similar sleepiness and affective symptoms. While significantly differing from controls, patients presented similarly increased light sleep, decreased slow-wave sleep and lowered sleep efficiency. Altered sleep quality, fatigue and sleepiness were significantly correlated to decreased slow-wave sleep and sleep fragmentation. Affective symptoms, fatigue and perceived sleep quality also correlated to PLM index. CONCLUSIONS: Sleep structure and efficiency were similarly impacted in isolated PLMD and in co-morbid RLS. RLS mainly worsened perceived sleep quality. Given that systematic treatment for isolated PLMD is currently not recommended, such results may question whether no or different-from-RLS treatment strategies are compatible with optimal care.

Transcranial Direct Current Stimulation Over the Right Frontal Inferior Cortex Decreases Neural Activity Needed to Achieve Inhibition: A Double-Blind ERP Study in a Male Population.

Inhibitory control refers to the ability to inhibit an action once it has been initiated. Impaired inhibitory control plays a key role in triggering relapse in some pathological states, such as addictions. Therefore, a major challenge of current research is to establish new methods to strengthen inhibitory control in these "high-risk" populations. In this attempt, the right inferior frontal cortex (rIFC), a neural correlate crucial for inhibitory control, was modulated using transcranial direct current stimulation (tDCS). Healthy participants (n = 31) were presented with a "Go/No-go" task, a well-known paradigm to measure inhibitory control. During this task, an event-related potential (ERP) recording (T1; 32 channels) was performed. One subgroup (n = 15) was randomly assigned to a condition with tDCS (anodal electrode was placed on the rIFC and the cathodal on the neck); and the other group (n = 16) to a condition with sham (placebo) tDCS. After one 20- minute neuromodulation session, all participants were confronted again with the same ERP Go/No-go task (T2). To ensure that potential tDCS effects were specific to inhibition, ERPs to a face-detection task were also recorded at T1 and T2 in both subgroups. The rate of commission errors on the Go/No-go task was similar between T1 and T2 in both neuromodulation groups. However, the amplitude of the P3d component, indexing the inhibition function per se, was reduced at T2 as compared with T1. This effect was specific for participants in the tDCS (and not sham) condition for correctly inhibited trials. No difference in the P3 component was observable between both subgroups at T1 and T2 for the face detection task. Overall, the present data indicate that boosting the rIFC specifically enhances inhibitory skills by decreasing the neural activity needed to correctly inhibit a response.

Neural correlates of correct and failed response inhibition in heavy versus light social drinkers: an fMRI study during a go/no-go task by healthy participants.

The ability to suppress responses that are inappropriate, as well as the mechanisms monitoring the accuracy of actions in order to compensate for errors, is central to human behavior. Neural alterations that prevent stopping an inaccurate response, combined with a decreased ability of error monitoring, are considered to be prominent features of alcohol abuse. Moreover, (i) alterations of these processes have been reported in heavy social drinkers (i.e. young healthy individuals who do not yet exhibit a state of alcohol dependence); and (ii) through longitudinal studies, these alterations have been shown to underlie subsequent disinhibition that may lead to future alcohol use disorders. In the present functional magnetic resonance imaging study, using a contextual Go/No-Go task, we investigated whether different neural networks subtended correct inhibitions and monitoring mechanisms of failed inhibitory trials in light versus heavy social drinkers. We show that, although successful inhibition did not lead to significant changes, neural networks involved in error monitoring are different in light versus heavy drinkers. Thus, while light drinkers exhibited activations in their right inferior frontal, right middle cingulate and left superior temporal areas; heavy drinkers exhibited activations in their right cerebellum, left caudate nucleus, left superior occipital region, and left amygdala. These data are functionally interpreted as reflecting a "visually-driven emotional strategy" vs. an "executive-based" neural response to errors in heavy and light drinkers, respectively. Such a difference is interpreted as a key-factor that may subtend the transition from a controlled social heavy consumption to a state of clinical alcohol dependence.

Methodological Considerations about the Use of Bimodal Oddball P300 in Psychiatry: Topography and Reference Effect.

Event-related potentials (ERPs) bimodal oddball task has disclosed increased sensitivity to show P300 modulations to subclinical symptoms. Even if the utility of such a procedure has still to be confirmed at a clinical level, gathering normative values of this new oddball variant may be of the greatest interest. We specifically addressed the challenge of defining the best location for the recording of P3a and P3b components and selecting the best reference to use by investigating the effect of an offline re-reference procedure on recorded bimodal P3a and P3b. Forty young and healthy subjects were submitted to a bimodal (synchronized and always congruent visual and auditory stimuli) three-stimulus oddball task in which 140 frequent bimodal stimuli, 30 deviant "target" stimuli and 30 distractors were presented. Task consisted in clicking as soon as possible on the targets, and not paying attention to frequent stimuli and distractors. This procedure allowed us to record, for each individual, the P3a component, referring to the novelty process related to distractors processing, and the P3b component, linked to the processing of the target stimuli. Results showed that both P3a and P3b showed maximal amplitude in Pz. However, P3a displayed a more central distribution. Nose reference was also shown to give maximal amplitudes compared with average and linked mastoids references. These data were discussed in light of the necessity to develop multi-site recording guidelines to furnish sets of ERPs data comparable across laboratories.

Just Swap Out of Negative Vibes? Rumination and Inhibition Deficits in Major Depressive Disorder: Data from Event-Related Potentials Studies.

Major depression is a serious disorder of impaired emotion regulation. Emotion hyperactivity leads to excessive negative ruminations that daily hijack the patient's mental life, impacting their mood. Evidence from past researches suggest that depressive patients present several cognitive impairments in attention and working memory, leading to a more acute selective attention for negative stimuli and a greater accessibility of negative memories. Recently, is has been proposed that impaired inhibitory functioning with regard to emotional information processing might be one of the mechanisms of ruminations linking memory, attention and depression. It seems that inhibition deficit is present at both the input level (i.e., the ability to reduce the interference from emotional distracters) and the higher level (i.e., the ability to direct the attention away from emotional material that has already been processed) of emotional information processing. Event-related potentials (ERP) have widely been used to study inhibition in adults suffering from various psychopathological states. In particular, depressive disorder has been linked to ERPs modulations, at early as well as at latter stages of the information-processing stream, when processing affective material. For instance, deficits in inhibiting negative information have been indexed by changes in the parameters (amplitudes and latencies) of early P2, P1 and N1 components while other ERP studies have shown an ability to differentiate depressed patients from normal controls based upon response inhibition difficulties in go-nogo tasks, indexed by later NoGo P3 differences. In this review, we will focus on results of ERP studies investigating inhibition and its interaction with emotional related cue processing in depressive populations. Implications for future research and theoretical perspectives will be discussed within the framework of current models of depressive disorder, based upon the hypothesis that negative ruminations are at the center of depression processes.

The bimodal P300 oddball component is decreased in patients with an adjustment disorder: An event-related potentials study.

OBJECTIVE: We found previously that use of a bimodal oddball design with synchronized pairs of audio-visual stimuli increased the sensitivity of the P300 wave to detect subclinical anxiety-depression in otherwise healthy subjects. Here, we wished to determine whether these P300 modulations would also be encountered when a clinical population comprised of patients with an adjustment disorder (AJD) was compared to healthy controls. METHOD: Two groups, each comprised of twenty-five participants (AJD patients, and controls; N=50) had to detect deviant stimuli among frequent stimuli in an oddball task by clicking on a button. Separate blocks involving audio (A), visual (V) or bimodal congruent (AV) stimuli were used and compared. RESULTS: P300 amplitudes of the control group were higher than those displayed by AJD patients, but only in the bimodal AV oddball task, while unimodal (visual or auditory) oddball tasks did not reveal any significant differences. CONCLUSIONS: The increased sensitivity of the bimodal P300 that we observed previously in subclinical anxiety-depression was also observed in AJD patients. SIGNIFICANCE: The impaired "bimodal congruence effect" in AJD suggests that these patients have altered integrative processes, which has potential implications for cognitive therapy.

Decoding of nonverbal language in alcoholism: A perception or a labeling problem?

Alcohol-dependent patients have difficulty recognizing social cues such as emotional facial expressions, prosody, and postures. However, most researchers describing these difficulties rely on labeling tasks. It therefore remains difficult to disentangle genuine emotion-decoding problems from emotion-labeling impairments. In the present study, 35 recently detoxified alcohol-dependent patients were compared with 35 matched controls on four emotion-pairing tasks to explore the distinction between labeling and perceptual abilities. First, 2 tasks were used to assess emotion-labeling ability (labeling task) and working memory (necessary to process emotional stimuli; control matching task). Next, 2 experimental pairing tasks were used to explore unimodal, Face-face or voice-voice) and cross-modal, Face-voice or voice-face) matching abilities in the absence of any labeling requirement. Patients had difficulty accurately processing voices in unimodal tasks and correctly matching emotional stimuli in cross-modal tasks. Specifically, they did not correctly identify neutral stimuli in unimodal or cross-modal tasks and did not correctly identify fear in cross-modal tasks. Reaction times were also slower in these patients. However, accuracy and reaction time (RT) differences between patients and controls were accounted for by including anxiety and depression scores as covariates in the model. These results suggest that emotion-decoding difficulties observed in recently detoxified alcohol-dependent patients are not due to a specific emotion-labeling impairment, but rather involve perceptual difficulties or later integrative processing steps in the brain. Future studies should directly compare depressed or nondepressed alcohol-dependent patients with depressive patients to disentangle the influences of these highly comorbid disorders on nonverbal language perception.

On the automaticity of response inhibition in individuals with alcoholism.

BACKGROUND AND OBJECTIVES: Response inhibition is usually considered a hallmark of executive control. However, recent work indicates that stop performance can become associatively mediated ('automatic') over practice. This study investigated automatic response inhibition in sober and recently detoxified individuals with alcoholism.. METHODS: We administered to forty recently detoxified alcoholics and forty healthy participants a modified stop-signal task that consisted of a training phase in which a subset of the stimuli was consistently associated with stopping or going, and a test phase in which this mapping was reversed. RESULTS: In the training phase, stop performance improved for the consistent stop stimuli, compared with control stimuli that were not associated with going or stopping. In the test phase, go performance tended to be impaired for old stop stimuli. Combined, these findings support the automatic inhibition hypothesis. Importantly, performance was similar in both groups, which indicates that automatic inhibitory control develops normally in individuals with alcoholism.. LIMITATIONS: This finding is specific to individuals with alcoholism without other psychiatric disorders, which is rather atypical and prevents generalization. Personalized stimuli with a stronger affective content should be used in future studies. CONCLUSIONS: These results advance our understanding of behavioral inhibition in individuals with alcoholism. Furthermore, intact automatic inhibitory control may be an important element of successful cognitive remediation of addictive behaviors..

Impaired non-verbal emotion processing in Pathological Gamblers.

Impaired perception of emotion in others has been described and confirmed in addictions with substances, but no such data exists regarding addictions without substances. As it has been hypothesized that toxic effect of substances on the brain was responsible for the impairments described, studying addictions without substances could be of interest to confirm this hypothesis. Twenty-two male pathological gamblers were compared to 22 male healthy controls matched for age and education level on non-verbal emotion perception tasks including faces, voices, and musical excerpts. Depression and anxiety levels were controlled for. Pathological gamblers significantly underestimated the intensity of peacefulness in music, and overall they were less accurate when reading emotion in voices and faces. They also overestimated emotional intensity in neutral voices and faces. Although anxiety levels did account for accuracy problems when detecting fear in voices and for overestimating emotions in neutral faces, anxiety levels did not explain the range of deficits observed. This is the first study showing non-verbal perception deficits in a purely behavioural addiction. These findings show that deficits in decoding non-verbal signals are associated with addictive behaviours per se, and are not due solely to toxic effects of substances on the brain.