Executive-affective connectivity in smokers viewing anti-smoking images: an fMRI study

Evidence for a hijacked brain reward system but no desensitized threat system in quitting-motivated smokers: An fMRI study

BACKGROUND AND AIMS

Several aspects of how quitting-motivated tobacco use disorder (TUD) subjects and never-smokers differ in terms of reward and threat processing remain unresolved. We aimed to examine aberrant reward and threat processes in TUD and the association with smoking characteristics.

DESIGN

A between- and within-subjects functional magnetic resonance imaging (fMRI) experiment with a 2 (groups) × 4 (stimulus type) factorial design. The experimental paradigm had four conditions: pictures of (1) cigarettes served as drug-related-positive cues, (2) food as alternative reward cues, (3) long-term consequences of smoking as drug-related-negative cues and (4) neutral pictures as control.

SETTING/PARTICIPANTS

Adult participants (n = 38 TUD subjects and n = 42 never-smokers) were recruited in Berlin, Germany.

MEASUREMENTS

As contrasts of primary interest, the interactions of group × stimulus-type were assessed. Significance threshold correction for multiple testing was carried out with the family-wise error method. Correlation analyses were used to test the association with smoking characteristics.

FINDINGS

The 2 × 2 interaction of smoking status and stimulus type revealed activations in the brain reward system to drug-related-positive cues in TUD subjects (between-subjects effect: P-values ≤ 0.036). As a response to drug-related-negative cues, TUD subjects showed no reduced activation of the aversive brain network. Within the TUD group, a significant negative association was found between response of the aversive brain system to drug-related-negative cues (within-subjects effect: P-values ≤ 0.021) and the number of cigarettes smoked per day (right insula r = -0.386, P = 0.024; left insula r = -0.351, P = 0.042; right ACC r = -0.359, P = 0.037).

CONCLUSIONS

Moderate smokers with tobacco use disorder appear to have altered brain reward processing of drug-related-positive (but not negative) cues compared with never smokers.

Aversive drug cues reduce cigarette craving and increase prefrontal cortex activation during processing of cigarette cues in quitting motivated smokers

Aversive drug cues can be used to support smoking cessation and create awareness of negative health consequences of smoking. Better understanding of the effects of aversive drug cues on craving and the processing of appetitive drug cues in abstinence motivated smokers is important to further improve their use in cessation therapy and smoking-related public health measures. In this study, 38 quitting motivated smokers underwent functional magnetic resonance imaging (fMRI) scanning while performing a novel extended cue-reactivity paradigm. Pictures of cigarettes served as appetitive drug cues, which were preceded by either aversive drug cues (e.g., smokers' leg) or other cues (neutral or alternative reward cues). Participants were instructed to rate their craving for cigarettes after presentation of drug cues. When aversive drug cues preceded the presentation of appetitive drug cues, behavioural craving was reduced and activations in prefrontal (dorsolateral prefrontal cortex) and paralimbic (dorsal anterior cingulate cortex [dACC] and anterior insulae) areas were enhanced. A positive association between behavioural craving reduction and neurofunctional activation changes was shown for the right dACC. Our results suggest that aversive drug cues have an impact on the processing of appetitive drug cues, both on a neurofunctional and a behavioural level. A proposed model states that aversive drug-related cues activate control-associated brain areas (e.g., dACC), leading to increased inhibitory control on reward-associated brain areas (e.g., putamen) and a reduction in subjective cravings.

Time-evolving dynamics in brain networks forecast responses to health messaging

Neuroimaging measures have been used to forecast complex behaviors, including how individuals change decisions about their health in response to persuasive communications, but have rarely incorporated metrics of brain network dynamics. How do functional dynamics within and between brain networks relate to the processes of persuasion and behavior change? To address this question, we scanned 45 adult smokers by using functional magnetic resonance imaging while they viewed anti-smoking images. Participants reported their smoking behavior and intentions to quit smoking before the scan and 1 month later. We focused on regions within four atlas-defined networks and examined whether they formed consistent network communities during this task (measured as allegiance). Smokers who showed reduced allegiance among regions within the default mode and fronto-parietal networks also demonstrated larger increases in their intentions to quit smoking 1 month later. We further examined dynamics of the ventromedial prefrontal cortex (vmPFC), as activation in this region has been frequently related to behavior change. The degree to which vmPFC changed its community assignment over time (measured as flexibility) was positively associated with smoking reduction. These data highlight the value in considering brain network dynamics for understanding message effectiveness and social processes more broadly.

The persuasion network is modulated by drug-use risk and predicts anti-drug message effectiveness

While a persuasion network has been proposed, little is known about how network connections between brain regions contribute to attitude change. Two possible mechanisms have been advanced. One hypothesis predicts that attitude change results from increased connectivity between structures implicated in affective and executive processing in response to increases in argument strength. A second functional perspective suggests that highly arousing messages reduce connectivity between structures implicated in the encoding of sensory information, which disrupts message processing and thereby inhibits attitude change. However, persuasion is a multi-determined construct that results from both message features and audience characteristics. Therefore, persuasive messages should lead to specific functional connectivity patterns among a priori defined structures within the persuasion network. The present study exposed 28 subjects to anti-drug public service announcements where arousal, argument strength, and subject drug-use risk were systematically varied. Psychophysiological interaction analyses provide support for the affective-executive hypothesis but not for the encoding-disruption hypothesis. Secondary analyses show that video-level connectivity patterns among structures within the persuasion network predict audience responses in independent samples (one college-aged, one nationally representative). We propose that persuasion neuroscience research is best advanced by considering network-level effects while accounting for interactions between message features and target audience characteristics.

Cognitive avoidance and aversive cues related to tobacco in male smokers

BACKGROUND

Treatment using aversive conditioning has been suggested for smoking cessation. The efficacy of this method is thought to be associated with cognitive avoidance. We compare differences in avoidance traits and patterns of associated brain activation in response to cues that induce cravings versus aversion between smokers and non-smokers.

METHODS

Fifteen smokers and fifteen non-smokers completed cue reactivity tasks while undergoing functional magnetic resonance imaging (fMRI) to examine brain responses to craving-inducing cues (Cr) and aversion-inducing cues (Av). Participant avoidant traits were also assessed.

RESULTS

Activation of the left frontal subcallosal gyrus in response to Cr was greater in smokers than in non-smokers. Smokers showed less activation in the right temporal lobe in response to Av than did non-smokers. Brain activation in response to Cr in the left frontal subcallosal gyrus was positively correlated with Fagerstrom Test for Nicotine Dependence (FTND) scores in smokers. Brain activation in response to Av in the right temporal lobe was negatively correlated with the Korean Version of the Cognitive Avoidance Questionnaire (KCAQ) scores in non-smokers.

CONCLUSIONS

Cognitive avoidance in smokers during aversive stimulation might result in sustaining addictive behaviors. On the other hand, non-smokers may be able to emotionally confront the adverse effects of smoking.

The use of neurocognitive methods in assessing health communication messages: A systematic review

We review 20 studies that examined persuasive processing and outcomes of health messages using neurocognitive measures. The results suggest that cognitive processes and neural activity in regions thought to reflect self-related processing may be more prominent in the persuasive process of self-relevant messages. Furthermore, activity in the medial prefrontal cortex, the superior temporal gyrus and the middle frontal gyrus were identified as predictors of message effectiveness, with the medial prefrontal cortex accounting for additional variance in behaviour change beyond that accounted for by self-report measures. Incorporating neurocognitive measures may provide a more comprehensive understanding of the processing and outcomes of health messages.

Can functional magnetic resonance imaging studies help with the optimization of health messaging for lifestyle behavior change? A systematic review

Unhealthy behaviors, including smoking, poor nutrition, excessive alcohol consumption, physical inactivity and sedentary lifestyles, are global risk factors for non-communicable diseases and premature death. Functional magnetic resonance imaging (fMRI) offers a unique approach to optimize health messages by examining how the brain responds to information relating to health. Our aim was to systematically review fMRI studies that have investigated variations in brain activation in response to health messages relating to (i) smoking; (ii) alcohol consumption; (iii) physical activity; (iv) diet; and (v) sedentary behavior. The electronic databases used were Medline/PubMed, Web of Science (Core Collection), PsychINFO, SPORTDiscuss, Cochrane Library and Open Grey. Studies were included if they investigated subjects aged ≥10years and were published before January 2017. Of the 13,836 studies identified in the database search, 18 studies (smoking k=15; diet k=2; physical activity/sedentary behavior k=1) were included in the review. The prefrontal cortex was activated in seven (47%) of the smoking-related studies and the physical activity study. Results suggest that activation of the ventromedial, dorsolateral and medial prefrontal cortex regions were predictive of subsequent behavior change following exposure to aversive anti-smoking stimuli. Studies investigating the neurological responses to anti-smoking material were most abundant. Of note, the prefrontal cortex and amygdala were most commonly activated in response to health messages across lifestyle behaviors. The review highlights an important disparity between research focusing on different lifestyle behaviors. Insights from smoking literature suggest fMRI may help to optimize health messaging in relation to other lifestyle behaviors.

Impaired Coupling between the Dorsomedial Prefrontal Cortex and the Amygdala in Schizophrenia Smokers Viewing Anti-smoking Images

BACKGROUND

Cigarette smoking is highly prevalent in schizophrenia and is one of the main factors contributing to the significantly decreased life expectancy in this population. Schizophrenia smokers, compared to their counterparts with no comorbid psychiatric disorder, are largely unaware and indifferent to the long-term negative consequences of cigarette smoking. The objective of this study was to determine, for the first time, if these meta-cognitive deficits are associated with neuro-functional alterations in schizophrenia smokers.

METHODS

Twenty-four smokers with no psychiatric disorder and 21 smokers with schizophrenia (DSM-IV criteria) were scanned using functional magnetic resonance imaging and exposed to anti-smoking images. Granger causality analyses were used to examine the effective connectivity between brain regions found to be significantly activated.

RESULTS

Across groups, potent activations were observed in the left ventro-lateral prefrontal cortex, the left amygdala (AMG), and the dorsomedial prefrontal cortex (dmPFC). Using the dmPFC as a seed region, we found an abnormal negative connectivity from the dmPFC to the AMG in schizophrenia smokers during the viewing of anti-smoking stimuli. This abnormal connectivity was not present during the viewing of aversive stimuli unrelated to tobacco.

DISCUSSION

Given the well-established roles of the dmPFC in social cognition and of the AMG in emotional processing, our results suggest that the relative indifference of schizophrenia smokers regarding the negative consequences of tobacco smoking could be explained by a cognitive-affective dissonance.

Increased ventro-medial prefrontal activations in schizophrenia smokers during cigarette cravings

BACKGROUND

Highly prevalent in schizophrenia, tobacco smoking substantially increases the risk of cardiac-related death. Compared to the general population, tobacco smoking cessation rates are lower in schizophrenia. Unfortunately, the reasons for these low cessation rates remain poorly understood. Recently, it has been shown that tobacco cravings are increased in schizophrenia smokers compared to smokers with no comorbid psychiatric disorder. In view of these results, we sought to examine - for the first time - the neurophysiologic responses elicited by cigarette cues in schizophrenia smokers. We hypothesized that cigarettes cues would elicit increased activations in brain regions involved in drug cravings in schizophrenia smokers relative to control smokers.

METHODS

Smokers with (n=18) and without (n=24) schizophrenia (DSM-IV criteria) were scanned using functional magnetic resonance imaging (fMRI) while viewing appetitive cigarette images.

RESULTS

Schizophrenia smokers and smokers with no psychiatric comorbidity did not differ in subjective cravings in response to appetitive smoking cues. However, in schizophrenia smokers relative to control smokers, we found that appetitive cigarette cues triggered increased activations of the bilateral ventro-medial prefrontal cortex, a core region of the brain reward system. Moreover, a negative correlation was observed between cigarette cravings and activations of the right ventro-medial prefrontal cortex in schizophrenia smokers.

DISCUSSION

The current results highlight a key role of the brain reward system in cigarette craving in schizophrenia, and suggest that the neurophysiologic mechanisms involved in the regulation of cue-induced cigarette craving are impaired in this population.

Neural correlates of cigarette health warning avoidance among smokers

BACKGROUND

Eye-tracking technology has indicated that daily smokers actively avoid pictorial cigarette package health warnings. Avoidance may be due to a pre-cognitive perceptual bias or a higher order cognitive bias, such as reduced emotional processing. Using electroencephalography (EEG), this study aimed to identify the temporal point at which smokers' responses to health warnings begin to differ.

METHOD

Non-smokers (n=20) and daily smokers (n=20) viewed pictorial cigarette package health warnings and neutral control stimuli. These elicited Event Related Potentials reflecting early perceptual processing (visual P1), pre-attentive change detection (visual Mismatch Negativity), selective attentional orientation (P3) and a measure of emotional processing, the Late Positive Potential (LPP).

RESULTS

There was no evidence for a difference in P1 responses between smokers and non-smokers. There was no difference in vMMN and P3 amplitude but some evidence for a delay in vMMN latency amongst smokers. There was strong evidence for delayed and reduced LPP to health warning stimuli amongst smokers compared to non-smokers.

CONCLUSION

We find no evidence for an early perceptual bias in smokers' visual perception of health warnings but strong evidence that smokers are less sensitive to the emotional content of cigarette health warnings. Future health warning development should focus on increasing the emotional salience of pictorial health warning content amongst smokers.