Brain indices of nicotine's effects on attentional bias to smoking and emotional pictures and to task-relevant targets

Cholinergic modulation of sensory perception and plasticity

Sensory systems are highly plastic, but the mechanisms of sensory plasticity remain unclear. People with vision or hearing loss demonstrate significant neural network reorganization that promotes adaptive changes in other sensory modalities as well as in their ability to combine information across the different senses (i.e., multisensory integration. Furthermore, sensory network remodeling is necessary for sensory restoration after a period of sensory deprivation. Acetylcholine is a powerful regulator of sensory plasticity, and studies suggest that cholinergic medications may improve visual and auditory abilities by facilitating sensory network plasticity. There are currently no approved therapeutics for sensory loss that target neuroplasticity. This review explores the systems-level effects of cholinergic signaling on human visual and auditory perception, with a focus on functional performance, sensory disorders, and neural activity. Understanding the role of acetylcholine in sensory plasticity will be essential for developing targeted treatments for sensory restoration.

Co-occurring tobacco and cannabis use in adolescents: Dissociable relationships with mediofrontal electrocortical activity during reward feedback processing

Differences in corticostriatal neural activity during feedback processing of rewards and losses have been separately related to cannabis and tobacco use but remain understudied relative to co-use in adolescents. Using high-density EEG (128 electrode system, 1000 Hz sampling), we examined event-related potentials (ERPs) elicited by monetary reward, neutral, and loss feedback during performance on a non-learning four-choice guessing task in a sample of non-deprived daily-cigarette-smoking adolescents (n = 36) who used tobacco and cannabis regularly (TC adolescents), and non-smoking healthy control adolescents (HCs) (n = 29). Peak amplitudes and latencies of mediofrontal ERPs indexing feedback-related negativities (FRNs) were used as outcomes in repeated-measures ANOVAs. No differences in FRNs were observed between TC and HC adolescents. Within TC adolescents, cannabis-use and tobacco-use variables had distinct relationships with the FRN, with cannabis-related problem severity being positively correlated with FRN amplitude during reward feedback and tobacco-related problem severity being negatively correlated with FRN latency during non-loss feedback (i.e., reward and neutral). These findings suggest that co-occurring cannabis and tobacco use may have dissociable relationships with feedback processing relating to each drug and support an incentive salience model of addiction severity related to cannabis use in adolescents.

Associations Between Smoking Abstinence, Inhibitory Control, and Smoking Behavior: An fMRI Study

Nicotine addiction is associated with dysregulated inhibitory control (IC), mediated by corticothalamic circuitry including the right inferior frontal gyrus (rIFG). Among sated smokers, worse IC task performance and greater IC-related rIFG activity have been shown to be associated with greater relapse vulnerability. The present study investigated the effects of smoking abstinence on associations between IC task performance, rIFG activation, and smoking behavior. Smokers (N = 26, 15 female) completed an IC task (Go/Go/No-go) during fMRI scanning followed by a laboratory-based smoking relapse analog task (SRT) on two visits: once when sated and once following 24 h of smoking abstinence. During the SRT, smokers were provided with monetary rewards for incrementally delaying smoking. A significant main effect of No-go accuracy on latency to smoke during the SRT was observed when collapsing across smoking states (abstinent vs. sated). Similarly, a significant main effect of IC-related activation in rIFG on SRT performance was observed across states. The main effect of state, however, was non-significant in both of these models. Furthermore, the interaction between smoking state and No-go accuracy on SRT performance was non-significant, indicating a similar relationship between IC and lapse vulnerability under both sated and abstinent conditions. The state X rIFG activation interaction on SRT performance was likewise non-significant. Post-hoc whole brain analyses indicated that abstinence resulted in greater IC-related activity in the right middle frontal gyrus (MFG) and insula. Activation during IC in these regions was significantly associated with decreased No-go accuracy. Moreover, greater abstinence induced activity in right MFG during IC was associated with smoking sooner on the SRT. These findings are bolstered by the extant literature on the effects of nicotine on executive function and also contribute novel insights on how individual differences in behavioral and neuroimaging measures of IC may influence relapse propensity independent of smoking state.

Anhedonia and Abstinence as Predictors of the Subjective Pleasantness of Positive, Negative, and Smoking-Related Pictures

Introduction

Anhedonia-diminished interest or pleasure in response to rewards-is a dimension implicated in several psychiatric disorders linked to smoking. This laboratory study sought to identify motivational mechanisms linking anhedonia and tobacco addiction by testing the hypothesis that anhedonia, abstinence, and their interaction would predict excesses and deficits in the perceived pleasantness of smoking-related and positive pictures, respectively. We assessed the pleasantness of negative pictures as a secondary outcome.

Methods

After a baseline session involving self-report measures of anhedonia and other factors, 125 regular smokers attended two counterbalanced experimental sessions (overnight abstinent and non-abstinent) at which they rated the pleasantness of positive, smoking-related, negative, and neutral (control) pictures presented via computer. The difference in pleasantness ratings of positive, smoking-related, and negative pictures relative to neutral pictures served as the index of participants' appraisal of the motivational salience of nondrug reward, drug reward, and aversive signals, respectively.

Results

With and without adjusting for sex and depressive symptoms, greater anhedonia significantly or marginally predicted greater pleasantness of smoking (vs. neutral), lower pleasantness of positive (vs. neutral), less unpleasantness of negative (vs. neutral) pictures (|βs| = 0.18 to 0.35, ps = .007 to .07). Anhedonia by abstinence interaction effects on pleasantness ratings of each stimulus category (vs. neutral) were not significant (|βs| ≤ 0.02, ps ≥ .36).

Conclusions

Anhedonia and abstinence additively increase the salience of smoking-related cues in anhedonic smokers. Smoking cessation efforts that attenuate sensitization to smoking stimuli may benefit anhedonic smokers early in quit attempts.

Implications

Taken together, these findings provide tentative evidence that anhedonia is associated with a relative imbalance in the motivational salience of drug relative to nondrug rewards and may be associated with a generalized hypo-reactivity to both positive and negative stimuli. Though some prior smoking research has evidenced this relative imbalance in anhedonia with self-report or a smoking-choice task, we additionally show that this pattern may extend to hyper-affective reactivity to smoking-related stimuli being coincident with hypo-affective reactivity to nondrug-related positive stimuli (ie, may extend to greater pleasantness ratings of smoking pictures being accompanied by lower pleasantness ratings of positive pictures).

Systemic Nicotine Increases Gain and Narrows Receptive Fields in A1 via Integrated Cortical and Subcortical Actions

Nicotine enhances sensory and cognitive processing via actions at nicotinic acetylcholine receptors (nAChRs), yet the precise circuit- and systems-level mechanisms remain unclear. In sensory cortex, nicotinic modulation of receptive fields (RFs) provides a model to probe mechanisms by which nAChRs regulate cortical circuits. Here, we examine RF modulation in mouse primary auditory cortex (A1) using a novel electrophysiological approach: current-source density (CSD) analysis of responses to tone-in-notched-noise (TINN) acoustic stimuli. TINN stimuli consist of a tone at the characteristic frequency (CF) of the recording site embedded within a white noise stimulus filtered to create a spectral “notch” of variable width centered on CF. Systemic nicotine (2.1 mg/kg) enhanced responses to the CF tone and to narrow-notch stimuli, yet reduced the response to wider-notch stimuli, indicating increased response gain within a narrowed RF. Subsequent manipulations showed that modulation of cortical RFs by systemic nicotine reflected effects at several levels in the auditory pathway: nicotine suppressed responses in the auditory midbrain and thalamus, with suppression increasing with spectral distance from CF so that RFs became narrower, and facilitated responses in the thalamocortical pathway, while nicotinic actions within A1 further contributed to both suppression and facilitation. Thus, multiple effects of systemic nicotine integrate along the ascending auditory pathway. These actions at nAChRs in cortical and subcortical circuits, which mimic effects of auditory attention, likely contribute to nicotinic enhancement of sensory and cognitive processing.

The effects of nicotine and non-nicotine smoking factors on working memory and associated brain function

Smoking abstinence impairs executive function, which may promote continued smoking behavior and relapse. The differential influence of nicotine and non-nicotine (i.e. sensory, motor) smoking factors and related neural substrates is not known. In a fully factorial, within-subjects design, 33 smokers underwent fMRI scanning following 24 hours of wearing a nicotine or placebo patch while smoking very low nicotine content cigarettes or remaining abstinent from smoking. During scanning, blood oxygenation level-dependent (BOLD) signal was acquired while participants performed a verbal N-back task. Following 24-hour placebo (versus nicotine) administration, accuracy on the N-back task was significantly worse and task-related BOLD signal lower in dorsomedial frontal cortex. These effects were observed irrespective of smoking. Our data provide novel evidence that abstinence-induced deficits in working memory and changes in underlying brain function are due in large part to abstinence from nicotine compared with non-nicotine factors. This work has implications both for designing interventions that target abstinence-induced cognitive deficits and for nicotine-reduction policy.

Attentional bias to smoking and other motivationally relevant cues is affected by nicotine exposure and dose expectancy

We investigated the effects of acute nicotine dose and expected dose on attentional bias (AB) to smoking and affective cues in overnight nicotine-deprived smokers (n=51; 24 women) using a balanced placebo design, which counterbalanced given nicotine dose (Given-NIC vs. Given-DENIC) with instructed nicotine dose expectancy (Told-NIC vs. Told-DENIC). Before and after smoking a study cigarette, smokers completed a vigilance task where they pressed buttons to every third consecutive even or odd digit, while ignoring intermittent smoking, pleasant, unpleasant, and neutral picture distracters. We examined the early posterior negativity (EPN) and late positive potential (LPP) components of the event-related potentials (ERPs) to the distracters, reaction time (RT) to the target digits, and ratings of the study cigarettes. The EPN was sensitive to both given and instructed nicotine dose, while the instructed dose moderated the impact of given dose for the LPP. The RT metrics were sensitive to given but not to instructed dose. The effects of given dose on ratings following cigarette smoking (e.g. enjoyment) were moderated by the instructed dose. The ERP findings suggest that the anticipated effects of nicotine improve attention much like receiving actual nicotine.

Depressive symptoms and responses to cigarette pack warning labels among Mexican smokers

OBJECTIVE

We examine whether having depressive symptoms (DS) is associated with different responses to cigarette package health warning labels (HWLs) before and after the implementation of pictorial HWLs in Mexico.

METHOD

We analyze data from adult smokers from Wave 4 and Wave 5 (n = 1,340) of the International Tobacco Control Policy Evaluation Project in Mexico. Seven Center for Epidemiological Studies Depression Scale (CES-D) items assessed DS, with scores ≥7 indicating elevated DS. Outcomes included: attention to HWLs, cognitive responses to HWLs, tobacco constituents awareness, putting off smoking due to HWLs, avoidance of HWLs, and awareness of telephone support for cessation (i.e., quitlines). Mixed effects models were used to assess main and interactive effects of DS and time (i.e., survey wave) on each outcome.

RESULTS

All HWL responses increased over time, except putting off smoking. Statistically significant interactions were found between DS and time for models of tobacco constituents awareness (b = -0.36, SE = 0.15, p = .022), putting off smoking (OR = 0.41, 95% CI [0.25, 0.66]), avoidance of HWLs (OR = 1.84, 95% CI [1.03, 3.29]), and quitline awareness (OR = 0.35, 95% CI [0.21, 0.56]). Compared to smokers with low DS, smokers with elevated DS reported stronger HWL responses at baseline; however, HWL responses increased over time among smokers with low DS, whereas HWL responses showed little or no change among smokers with elevated DS.

DISCUSSION

Population-level increases in HWL responses after pictorial HWLs were introduced in Mexico appeared mostly limited to smokers with low DS. In general, however, smokers with elevated DS reported equivalent or stronger HWL responses than smokers with low DS.

Effects of transcranial direct current stimulation (tDCS) on cognition, symptoms, and smoking in schizophrenia: A randomized controlled study

Schizophrenia is characterized by cognitive deficits which persist after acute symptoms have been treated or resolved. Transcranial direct current stimulation (tDCS) has been reported to improve cognition and reduce smoking craving in healthy subjects but has not been as carefully evaluated in a randomized controlled study for these effects in schizophrenia. We conducted a randomized double-blind, sham-controlled study of the effects of 5 sessions of tDCS (2 milliamps for 20minutes) on cognition, psychiatric symptoms, and smoking and cigarette craving in 37 outpatients with schizophrenia or schizoaffective disorder who were current smokers. Thirty subjects provided evaluable data on the MATRICS Consensus Cognitive Battery (MCCB), with the primary outcome measure, the MCCB Composite score. Active compared to sham tDCS subjects showed significant improvements after the fifth tDCS session in MCCB Composite score (p=0.008) and on the MCCB Working Memory (p=0.002) and Attention-Vigilance (p=0.027) domain scores, with large effect sizes. MCCB Composite and Working Memory domain scores remained significant at Benjamini-Hochberg corrected significance levels (α=0.05). There were no statistically significant effects on secondary outcome measures of psychiatric symptoms (PANSS scores), hallucinations, cigarette craving, or cigarettes smoked. The positive effects of tDCS on cognitive performance suggest a potential efficacious treatment for cognitive deficits in partially recovered chronic schizophrenia outpatients that should be further investigated.

Neuronal effects of nicotine during auditory selective attention

RATIONALE

Although the attention-enhancing effects of nicotine have been behaviorally and neurophysiologically well-documented, its localized functional effects during selective attention are poorly understood.

OBJECTIVES

In this study, we examined the neuronal effects of nicotine during auditory selective attention in healthy human nonsmokers. We hypothesized to observe significant effects of nicotine in attention-associated brain areas, driven by nicotine-induced increases in activity as a function of increasing task demands.

METHODS

A single-blind, prospective, randomized crossover design was used to examine neuronal response associated with a go/no-go task after 7 mg nicotine or placebo patch administration in 20 individuals who underwent functional magnetic resonance imaging at 3T. The task design included two levels of difficulty (ordered vs. random stimuli) and two levels of auditory distraction (silence vs. noise).

RESULTS

Significant treatment × difficulty × distraction interaction effects on neuronal response were observed in the hippocampus, ventral parietal cortex, and anterior cingulate. In contrast to our hypothesis, U and inverted U-shaped dependencies were observed between the effects of nicotine on response and task demands, depending on the brain area.

CONCLUSIONS

These results suggest that nicotine may differentially affect neuronal response depending on task conditions. These results have important theoretical implications for understanding how cholinergic tone may influence the neurobiology of selective attention.

The effects of nicotine dose expectancy and motivationally relevant distracters on vigilance

The imminence of drug use (i.e., drug availability) has been found to be related to intensity of drug craving, but its effects on attentional bias to drug cues are unclear. This study investigated the effects of nicotine availability on attentional bias to smoking, affective, and neutral cues in a sample of adult smokers during a vigilance task. At the beginning of each of 4 laboratory sessions, overnight nicotine-deprived smokers (n = 51) were instructed that they would smoke a cigarette containing either nicotine (Told-NIC) or no nicotine (Told-DENIC) after completing the rapid visual information processing task with central emotional distracters (RVIP-CED). The RVIP-CED presented digits at a rapid pace, with participants instructed to respond with button presses to every third consecutive even or odd digit. Some digits were preceded by smoking, pleasant, unpleasant, or neutral distracter slides. During Told-NIC conditions, participants produced significantly longer reaction time (RT) latency than during Told-DENIC conditions. RT sensitivity (d'), a measure of the ability to discriminate true positives from false positives, was significantly lower during the Told-NIC than during the Told-DENIC conditions to targets following cigarette distracters. These results suggest that nicotine-deprived smokers expecting to imminently smoke a cigarette experience greater distraction, particularly to smoking-related stimuli, than when expecting to smoke a denicotinized cigarette.

Attentional bias modification for addictive behaviors: clinical implications

When a person has a goal of drinking alcohol or using another addictive substance, the person appears to be automatically distracted by stimuli related to the goal. Because the attentional bias might propel the person to use the substance, an intervention might help modify it. In this article, we discuss techniques that have been developed to help people overcome their attentional bias for alcohol, smoking-related stimuli, drugs, or unhealthy food. We also discuss how these techniques are being adapted for use on mobile devices. The latter would allow people with an addictive behavior to use the attentional training in privacy and as frequently as needed. The attentional training techniques discussed here appear to have several advantages. They are inexpensive, can be fun to use, and have flexibility in when, where, and how often they are used. The evidence so far also suggests that they are effective.

Implicit attitudes toward smoking: how the smell of cigarettes influences responses of college-age smokers and nonsmokers

The habit of smoking may have automatic behavioral components guided by implicit attitudes. Smokers' attitudes toward smoking should thus be less negative than nonsmokers', so that a salient smoking cue (smell) is able to activate positive aspects of these attitudes. An affective priming task was used to explore this hypothesis. Unexpectedly, smokers and nonsmokers showed equally negative implicit attitudes, irrespective of smell. Smokers exposed to the cigarette smell did, however, display generally slower responses than nonsmokers, suggesting attentional bias. This could have implications for smoking policies in contexts where attentional factors affect performance.

Effects of nicotine on emotional distraction of attentional orienting: evidence of possible moderation by dopamine type 2 receptor genotype

INTRODUCTION

Growing evidence suggests that attentional bias to, and distraction by, emotional stimuli may moderate affective states and motivation for nicotine and other drug use.

METHODS

The present study assessed the effects of nicotine and dopamine receptor genotype on distraction by emotional pictures, during a modified spatial attention task, in 46 overnight-deprived smokers.

RESULTS

Relative to placebo, 14mg nicotine patch produced shorter overall reaction times (RTs) and individuals with two dopamine type 2 receptor (DRD2) A2 alleles exhibited the greatest RT benefit from nicotine following emotionally negative pictures after the longest cue-target delay (800ms), but benefitted least from nicotine following positive pictures after the shortest delay (400ms). In contrast, at the shortest delay, A1 carriers did not benefit from nicotine following emotionally negative pictures but did following positive ones.

CONCLUSIONS

These genetic differences in the effects of nicotine on attention immediately following emotionally positive versus negative stimuli may reflect differential excitatory and inhibitory transmitter processes related to approach (reward) and avoidance (punishment) sensitivities of dopamine-related neural networks that support positive and negative affect.

Nicotine differentially modulates antisaccade eye-gaze away from emotional stimuli in nonsmokers stratified by pre-task baseline performance

RATIONALE AND OBJECTIVE

Studies indicate that nicotine enhances some aspects of attention and executive functioning and attenuates the attentional salience of emotionally negative distractors. The purpose of this study was to assess whether nicotine can enhance executive control over prepotent responses in emotional contexts in nonsmokers and whether such enhancement is greater in individuals with low baseline performance (BP).

METHODS

The antisaccade task (AST) measures the inhibition of the tendency to glance in the direction of the onset of a visual stimulus and thus is an index of control over prepotent responses. Ten male and 14 female nonsmokers wore nicotine and placebo patches on counterbalanced days that included emotional picture primes and targets.

RESULTS

There were significant beneficial effects of nicotine on antisaccade reaction time (RT). These beneficial effects occurred in individuals with poor and average BP, but not in high baseline performers. In slow baseline RT individuals, nicotine reduced RTs associated with negative targets in the left visual field (VF) and reduced RTs associated with positive and neutral targets in the right VF. In contrast, in the average baseline group, nicotine reduced RTs for positive targets in both VFs and neutral targets in the left VF.

CONCLUSIONS

The results suggest that nicotine may produce its effects by enhancing executive functions and that the differential effects as a function of VF, target emotion, and group may also reflect lateralized differences in the effects of nicotine on brain reactivity to emotional stimuli.

Beyond cue reactivity: blunted brain responses to pleasant stimuli predict long-term smoking abstinence

Identifying addicts with higher risk of relapse would provide the opportunity to implement individualized interventions and increase cessation success rates. Unfortunately, the ability to predict the long-term success of drug cessation treatments continues to elude researchers. We tested whether brain responses to emotional and cigarette-related pictures were predictive of the ability to abstain from smoking. Smokers interested in quitting (n=180) participated in a smoking cessation clinical trial. Before the initiation of any treatment, we recorded event-related potentials (ERPs) evoked by emotional (both pleasant and unpleasant), neutral, and cigarette-related images. Cluster analysis was used to assign smokers to two groups based on the amplitude of the late positive potential (LPP) to the experimental stimuli. While both groups showed enhanced responses to cigarette-related cues, one group (n=81) also showed blunted brain responses to intrinsically pleasant stimuli. Smokers in the latter group were significantly less likely to be abstinent at 10, 12 and 24 weeks after their quit date. In conclusion, using ERPs, a direct measure of brain activity, we found that smokers with blunted brain responses to intrinsically pleasant stimuli had lower rates of long-term smoking abstinence. This response offers a new biomarker for identifying smokers at higher risk of relapse and for testing the efficacy of new interventions aimed at normalizing brain reward systems' responses to intrinsically pleasant stimuli.

Effects of Nicotine on Emotional Reactivity in PTSD and Non-PTSD Smokers: Results of a Pilot fMRI Study

There is evidence that individuals with posttraumatic stress disorder (PTSD) may smoke in part to regulate negative affect. This pilot fMRI study examined the effects of nicotine on emotional information processing in smokers with and without PTSD. Across groups, nicotine increased brain activation in response to fearful/angry faces (compared to neutral faces) in ventral caudate. Patch x Group interactions were observed in brain regions involved in emotional and facial feature processing. These preliminary findings suggest that nicotine differentially modulates negative information processing in PTSD and non-PTSD smokers.

Smoking abstinence and depressive symptoms modulate the executive control system during emotional information processing

Smoking abstinence disrupts affective and cognitive processes. In this study, functional magnetic resonance imaging (fMRI) was used to investigate the effects of smoking abstinence on emotional information processing. Smokers (n = 17) and non-smokers (n = 18) underwent fMRI while performing an emotional distractor oddball task in which rare targets were presented following negative and neutral task-irrelevant distractors. Smokers completed two sessions: once following 24-hour abstinence and once while satiated. The abstinent versus satiated states were compared by evaluating responses to distractor images and to targets following each distractor valence within frontal executive and limbic brain regions. Regression analyses were done to investigate whether self-reported negative affect influences brain response to images and targets. Exploratory regression analyses examined relations between baseline depressive symptoms and smoking state on brain function. Smoking state affected response to target detection in the right inferior frontal gyrus (IFG). During satiety, activation was greater in response to targets following negative versus neutral distractors; following abstinence, the reverse was observed. Withdrawal-related negative affect was associated with right insula activation to negative images. Finally, depression symptoms were associated with abstinence-induced hypoactive response to negative emotional distractors and task-relevant targets following negative distractors in frontal brain regions. Neural processes related to novelty detection/attention in the right IFG may be disrupted by smoking abstinence and negative stimuli. Reactivity to emotional stimuli and the interfering effects on cognition are moderated by the magnitude of smoking state-dependent negative affect and baseline depressive symptoms.

Nicotine withdrawal modulates frontal brain function during an affective Stroop task

BACKGROUND

Among nicotine-dependent smokers, smoking abstinence disrupts multiple cognitive and affective processes including conflict resolution and emotional information processing (EIP). However, the neurobiological basis of abstinence effects on resolving emotional interference on cognition remains largely uncharacterized. In this study, functional magnetic resonance imaging (fMRI) was used to investigate smoking abstinence effects on emotion-cognition interactions.

METHODS

Smokers (n = 17) underwent fMRI while performing an affective Stroop task (aST) over two sessions: once following 24-h abstinence and once following smoking as usual. The aST includes trials that serially present incongruent or congruent numerical grids bracketed by neutral or negative emotional distractors and view-only emotional image trials. Statistical analyses were conducted using a statistical threshold of p < 0.05 cluster corrected.

RESULTS

Smoking abstinence increased Stroop blood-oxygenation-level-dependent response in the right middle frontal and rostral anterior cingulate gyri. Moreover, withdrawal-induced negative affect was associated with less activation in frontoparietal regions during negative emotional information processing; whereas, during Stroop trials, negative affect predicted greater activation in frontal regions during negative, but not neutral emotional distractor trials.

CONCLUSION

Hyperactivation in the frontal executive control network during smoking abstinence may represent a need to recruit additional executive resources to meet task demands. Moreover, abstinence-induced negative affect may disrupt cognitive control neural circuitry during EIP and place additional demands on frontal executive neural resources during cognitive demands when presented with emotionally distracting stimuli.

Does coffee enriched with chlorogenic acids improve mood and cognition after acute administration in healthy elderly? A pilot study

RATIONALE

Caffeine exerts positive effects on cognitive and behavioral processes, especially in sub-optimal conditions when arousal is low. Apart from caffeine, coffee contains other compounds including the phenolic compounds ferulic acid, caffeic acid, and the chlorogenic acids, which have purported antioxidant properties. The chlorogenic acids are the most abundant family of compounds found in coffee, yet their effects on cognition and mood have not been investigated.

OBJECTIVES

This study aims to ascertain whether a coffee rich in chlorogenic acid modulates brain function.

METHODS

The present pilot study examined the acute effects of decaffeinated coffee with regular chlorogenic acid content and decaffeinated coffee with high chlorogenic acid content on mood and cognitive processes, as measured by behavioral tasks and event-related potentials (ERPs). Performance and ERP responses to a battery of cognitive tasks were recorded at baseline and following the equivalent of three cups of coffee in a randomized, double-blind, crossover study of 39 healthy older participants.

RESULTS

Compared with the decaffeinated coffee with regular chlorogenic acid and placebo, caffeinated coffee showed a robust positive effect on higher-level mood and attention processes. To a lesser extent, the decaffeinated coffee high in chlorogenic acid also improved some mood and behavioral measures, relative to regular decaffeinated coffee.

CONCLUSIONS

Our pilot results suggest that non-caffeine compounds in coffee such as the chlorogenic acids may be capable of exerting some acute behavioral effects, thus warranting further investigation.

Emotional reactivity to emotional and smoking cues during smoking abstinence: potentiated startle and P300 suppression

Negative affect is thought to be an important factor in the maintenance of cigarette smoking, and thus it is important to further develop objective measures of smoking-related emotional responses. Nonsmokers, non abstinent smokers, and abstinent smokers participated in a cue reactivity task where eyeblink startle amplitude and startle probe P300 (P3) suppression were measured during the presentation of emotional pictures.During unpleasant pictures, the amplitude of both measures was smaller in non abstinent smokers than in nonsmokers or abstinent smokers. P3 suppression, but not startle amplitude, was larger in abstinent smokers than in nonsmokers. Abstinence-induced increases in cigarette craving were associated with P3 suppression during tobacco-related pictures. Results suggest that tobacco abstinence increases emotional reactivity to unpleasant stimuli, which is consistent with negative reinforcement models of tobacco addiction.

Implicit and explicit selective attention to smoking cues in smokers indexed by brain potentials

Substance use disorders are characterized by cognitive processing biases, such as automatically detecting and orienting attention towards drug-related stimuli. However, it is unclear how, when and what kind of attention (i.e. implicit, explicit) interacts with the processing of these stimuli. In addition, it is unclear whether smokers are hypersensitive to emotionally significant cues in general or to smoking-related cues in particular. The present event-related potential study aimed to enhance insight in drug-related processing biases by manipulating attention for smoking and other motivationally relevant (emotional) cues in smokers and non-smokers using a visual oddball task. Each of the stimulus categories served as a target (explicit attention; counting) or as a non-target (implicit attention; oddball) category. Compared with non-smokers, smokers' P300 (350-600 ms) was enhanced to smoking pictures under both attentional conditions. P300 amplitude did not differ between groups in response to positive, negative, and neutral cues. It can be concluded from this study that attention manipulation affects the P300 differently in smokers and non-smokers. Smokers display a specific bias to smoking-related cues, and this bias is present during both explicit and implicit attentional processing. Overall, it can be concluded that both explicit and implicit attentional processes appear to play an important role in drug-related processing bias.

Nicotine increases neural response to unpleasant stimuli and anxiety in non-smokers

Studies in smokers suggest that nicotine might exert anxiolytic, stress-dampening and mood-enhancing effects and beneficially influences neural processing of affective information. Regarding non-smokers, results are inconsistent, and no data exist on the effect of nicotine on neural emotion processing. We applied functional magnetic resonance imaging (fMRI) to assess the influence of nicotine on brain activation during processing of emotional stimuli in 31 non-smokers with a maximum lifetime cigarette consumption of 20 cigarettes. Participants were subjected to two fMRI scans with event-related presentations of images taken from the International Affective Picture System, receiving nicotine (2 mg) and placebo gums in a double-blinded, randomized cross-over design. Furthermore, subjective affect was assessed. Nicotine increased brain activity in response to unpleasant stimuli in the amygdala, anterior cingulate cortex (ACC) and basal ganglia, whereas processing of pleasant stimuli was not altered. Psychophysiological interaction (PPI) analyses revealed that nicotine increased connectivity between the amygdala and the perigenual ACC (pACC) during processing of unpleasant stimuli and decreased connectivity between those structures during processing of pleasant stimuli. Participants reported higher state anxiety under nicotine than placebo. A single dose of nicotine acted as a stressor in non-smokers, leading to increased anxiety and neural activation elicited by unpleasant stimuli as well as altered connectivity within the amygdala-pACC circuit. Besides the possibility that reactions to nicotine may differ between non-smokers and smokers due to tolerance and neuroadaptive processes that occur during prolonged nicotine use, a priori differences in smokers and non-smokers might potentially explain diverse effects of nicotine on affect and emotional reactivity.

Nicotine primes attention to competing affective stimuli in the context of salient alternatives

Despite the importance of the subject, the effects of nicotine on the interplay between affect and attentional bias are not clear. This interplay was assessed with a novel design of the Primed Attentional Competition Task (PACT). It included a 200-ms duration emotional priming picture (negative, positive, or neutral) followed by a dual-target picture of two emotional faces side-by-side. A second task included an emotional priming picture followed by a single emotional target picture in a classic affective priming (CAP) task, assessing reaction time to identify the valence. Smokers completed the tasks in a double-blind repeated measures design wearing a nicotine patch on one day and a placebo patch on the other day. Consistent with hypotheses, nicotine enhanced the effectiveness of positive primes to bias first gaze-fixations (FGFs) toward neutral pictures relative to negative pictures and attenuated the effectiveness of negative primes on FGFs toward negative pictures, but did not bias performance in the CAP task where competing target stimuli were not present. These effects of nicotine on affective priming and attentional bias toward competing reinforcers may contribute to smoking motivation.

Cigarette cues capture smokers' attention: evidence from event-related potentials

Abstract Before starting a smoking cessation treatment, 51 smokers took part in a study aimed at investigating brain mechanisms associated with attention allocation. Event-related potentials to acoustic startle probes were recorded from 129 sensors during the presentation of neutral, pleasant, unpleasant, and cigarette-related pictures. Results indicated that the amplitude of the startle probe P3 component was reduced for pleasant, unpleasant, and cigarette-related conditions relative to neutral. Surface Laplacian estimates showed that sources of electrocortical activity under frontal and parietal sensors contributed to the modulation of this effect. For smokers, cigarette-related stimuli, like intrinsically motivating ones, capture attentional resources and therefore reduce the ability to process competing stimuli. The depletion of attentional resources in the presence of cigarette-related cues may contribute to the high relapse rate observed during attempts to quit smoking.

Effects of nicotine on novelty detection and memory recognition performance: double-blind, placebo-controlled studies of smokers and nonsmokers

RATIONALE

Dependent smokers exhibit deficits in attentional and memory processes when smoking abstinent as compared to when satiated. While nicotine replacement therapy improves attention during abstinence, it is unclear whether this is due to the alleviation of withdrawal-related deficits or inherent beneficial effects of nicotine.

OBJECTIVES

The primary aim of these studies was to test whether nicotine exerts a beneficial effect on novelty detection and whether such effects occur in nonsmokers as well as habitual smokers.

MATERIALS AND METHODS

In two parallel, double-blind, placebo-controlled studies, 24 smokers (study 1) and 24 nonsmokers (study 2) were tested in two counterbalanced sessions: once while wearing a nicotine patch (smokers = 14 mg; nonsmokers = 7 mg) and once while wearing a placebo patch. On each day, participants performed three content-specific oddball tasks (perceptual, semantic, and emotional) that required them to press a button whenever they saw a novel target (20% of stimuli) embedded in a stream of common nontarget stimuli (80% of stimuli). Recognition memory for targets was subsequently tested. Reports of mood, smoking withdrawal, patch side effects, and blind success were collected in each session.

RESULTS

Among smokers, compared to placebo, nicotine decreased target reaction time during all oddball tasks. Among nonsmokers, nicotine increased target detection accuracy and subsequent memory recognition. Nicotine's enhancement on each respective measure was not task-content specific in either sample.

CONCLUSIONS

These data suggest that acute nicotine administration may exert direct beneficial effects on novelty detection and subsequent memory recognition in both smokers and nonsmokers. Moreover, these effects are not content-specific.

Subliminal processing of smoking-related and affective stimuli in tobacco addiction

Cognitive processing biases toward smoking-related and affective cues may play a role in tobacco dependence. Because processing biases may occur outside conscious awareness, the current study examined processing of smoking-related and affective stimuli presented at subliminal conditions. A pictorial subliminal repetition priming task was administered to three groups: (1) Nonsmokers (n = 56); (2) Smokers (> or =10 cigarettes/day) who had been deprived from smoking for 12 h (n = 47); and (3) Nondeprived smokers (n = 66). Prime stimuli were presented briefly (17 ms) and were followed by a mask (to render them unavailable to conscious awareness) and then a target. Participants were required to make a speeded classification to the target. A posttask awareness check was administered to ensure that participants could not consciously perceive the briefly presented primes (i.e., smoking paraphernalia, neutral office supplies, and happy, angry, and neutral facial expressions). The groups differed in the degree to which they exhibited a processing bias for smoking-related stimuli, F(2, 166) = 4.99, p = .008. Deprived smokers exhibited a bias toward processing smoking (vs. neutral office supply) stimuli, F(1, 46) = 5.67, p = .02, whereas nondeprived smokers and nonsmokers did not (ps > .22). The three groups did not differ in the degree to which they exhibited a subliminal processing bias for affective stimuli. Tobacco deprivation appears to increase smokers' subliminal processing of smoking-related (vs. neutral) stimuli but does not influence subliminal processing of affective stimuli. Future research should investigate whether subliminal biases toward smoking-related stimuli influence relapse.

Effects of nicotine and depressive traits on affective priming of lateralized emotional word identification

Based on evidence suggesting that depressive traits, emotional information processing, and the effects of nicotine may be mediated by lateralized brain mechanisms, analyses assessed the influence of depressive traits and nicotine patch on emotional priming of lateralized emotional word identification in 61 habitual smokers. Consistent with hypotheses, nicotine as compared to placebo patch enhanced right visual field (RVF) emotional word identification while decreasing performance of emotional word identification in the left visual field (LVF). Nicotine also enhanced positive affect and decreased negative affect. Consistent with the Heller model of depression, scoring high in depressive traits was associated with a general decrease in LVF emotional word identification. Additionally, this general LVF deficit was especially pronounced for positive word identification in individuals scoring high in trait depression. Positive primes facilitated positive target identification in the RVF and negative primes facilitated negative target identification in the LVF. Thus, nicotine promoted a LVF word-identification deficit similar to that observed in those with depressive traits. However, nicotine also enhanced RVF processing and reduced negative affect, whereas it enhanced positive affect.