Dongju Seo

Disrupted Ventromedial Prefrontal Function, Alcohol Craving, and Subsequent Relapse Risk

IMPORTANCE Alcohol dependence is a chronic relapsing illness; stress, alcohol-related cues, and neutral-relaxing states significantly influence craving and relapse risk. However, neural mechanisms underlying the association between these states and alcohol craving and relapse risk remain unclear. OBJECTIVES To identify neural correlates associated with alcohol craving and relapse outcomes in 45 treatment-engaged, 4- to 8-week abstinent alcohol-dependent (AD) patients, and to compare brain responses of 30 demographically matched AD patients and 30 healthy control subjects during stress, alcohol, and neutral-relaxing cues. DESIGN Functional magnetic resonance imaging study while participants were engaging in brief individualized script-driven imagery trials of stress, alcohol cues, and neutral-relaxing scenarios, and a prospective clinical outcome design to assess alcohol relapse 90 days postdischarge from inpatient treatment in the AD group. SETTINGS Inpatient treatment setting in a community mental health center and hospital-based research unit. PATIENTS Forty-five recovering AD patients in inpatient treatment for examining relapse, and 30 healthy control subjects demographically matched to 30 AD patients (subgroup of the relapse sample) for group comparisons. INTERVENTION Twelve-step recovery-based addiction treatment for the patient group. MAIN OUTCOMES AND MEASURES Brain response, alcohol craving, and relapse outcome measures (time to relapse and relapse severity). RESULTS Increased ventromedial prefrontal cortex (vmPFC) and anterior cingulate cortex (ACC) activation during neutral-relaxing trials was correlated with high alcohol cue-induced and stress-induced craving in early recovering AD patients (x = 6, y = 43, z = -6; P < .01, whole-brain corrected). This vmPFC/ACC hyperactivity significantly predicted subsequent alcohol relapse, with a hazards ratio greater than 8 for increased relapse risk. Additionally, vmPFC/ACC hyperactivation during neutral trials and reduced activity during stress trials were each predictive of greater days of alcohol used after relapse (P < .01, whole-brain corrected). In contrast, matched control subjects showed the reverse pattern of vmPFC/ACC responses to stress, alcohol cues, and relaxed trials (F = 6.42; P < .01, whole-brain corrected). CONCLUSIONS AND RELEVANCE Findings indicate that disrupted vmPFC/ACC function plays a role in jeopardizing recovery from alcoholism and may serve as a neural marker to identify those at risk for alcohol relapse.

Circulating glucose levels modulate neural control of desire for high-calorie foods in humans

Obesity is a worldwide epidemic resulting in part from the ubiquity of high-calorie foods and food images. Whether obese and nonobese individuals regulate their desire to consume high-calorie foods differently is not clear. We set out to investigate the hypothesis that circulating levels of glucose, the primary fuel source for the brain, influence brain regions that regulate the motivation to consume high-calorie foods. Using functional MRI (fMRI) combined with a stepped hyperinsulinemic euglycemic-hypoglycemic clamp and behavioral measures of interest in food, we have shown here that mild hypoglycemia preferentially activates limbic-striatal brain regions in response to food cues to produce a greater desire for high-calorie foods. In contrast, euglycemia preferentially activated the medial prefrontal cortex and resulted in less interest in food stimuli. Indeed, higher circulating glucose levels predicted greater medial prefrontal cortex activation, and this response was absent in obese subjects. These findings demonstrate that circulating glucose modulates neural stimulatory and inhibitory control over food motivation and suggest that this glucose-linked restraining influence is lost in obesity. Strategies that temper postprandial reductions in glucose levels might reduce the risk of overeating, particularly in environments inundated with visual cues of high-calorie foods.

Sex differences in neural responses to stress and alcohol context cues.

Stress and alcohol context cues are each associated with alcohol‐related behaviors, yet neural responses underlying these processes remain unclear. This study investigated the neural correlates of stress and alcohol context cue experiences and examined sex differences in these responses. Using functional magnetic resonance imaging, brain responses were examined while 43 right‐handed, socially drinking, healthy individuals (23 females) engaged in brief guided imagery of personalized stress, alcohol‐cue, and neutral‐relaxing scenarios. Stress and alcohol‐cue exposure increased activity in the cortico–limbic–striatal circuit (P < 0.01, corrected), encompassing the medial prefrontal cortex (mPFC), orbitofrontal cortex (OFC), anterior cingulate cortex (ACC), left anterior insula, striatum, and visuomotor regions (parietal and occipital lobe, and cerebellum). Activity in the left dorsal striatum increased during stress, while bilateral ventral striatum activity was evident during alcohol‐cue exposure. Men displayed greater stress‐related activations in the mPFC, rostral ACC, posterior insula, amygdala, and hippocampus than women, whereas women showed greater alcohol‐cue‐related activity in the superior and middle frontal gyrus (SFG/MFG) than men. Stress‐induced anxiety was positively associated with activity in emotion‐modulation regions, including the medial OFC, ventromedial PFC, left superior‐mPFC, and rostral ACC in men, but in women with activation in the SFG/MFG, regions involved in cognitive processing. Alcohol craving was significantly associated with the striatum (encompassing dorsal, and ventral) in men, supporting its involvement in alcohol “urge” in healthy men. These results indicate sex differences in neural processing of stress and alcohol‐cue experiences and have implications for sex‐specific vulnerabilities to stress‐ and alcohol‐related psychiatric disorders. Hum Brain Mapp, 2011.

Guanfacine effects on stress, drug craving and prefrontal activation in cocaine dependent individuals: preliminary findings

Cocaine dependence is associated with increased stress and drug cue-induced craving and physiological arousal but decreased prefrontal activity to emotional and cognitive challenge. As these changes are associated with relapse risk, we investigated the effects of α2 receptor agonist guanfacine on these processes. Twenty-nine early abstinent treatment-seeking cocaine dependent individuals were randomly assigned to either daily placebo or guanfacine (up to 3 mg) for four weeks. In a laboratory experiment, all patients were exposed to three 10-min guided imagery conditions (stress/stress, drug cue/drug cue, stress/drug cue), one per day, consecutively in a random, counterbalanced order. Subjective craving, anxiety and arousal as well as cardiovascular output were assessed repeatedly. Brain response to stress, drug cue and relaxing imagery was also assessed during a functional magnetic resonance (fMRI) imaging session. In the current study, guanfacine was found to be safe and well-tolerated. Lower basal heart rate and blood pressure was observed in the guanfacine versus placebo group. Guanfacine lowered stress and cue-induced nicotine craving and cue-induced cocaine craving, anxiety and arousal. The guanfacine group also showed increased medial and lateral prefrontal activity following stress and drug cue exposure compared with placebo. Data suggest further exploration of guanfacine is warranted in terms of its potential for reducing stress-induced and cue-induced drug craving and arousal.

Cumulative Adversity Sensitizes Neural Response to Acute Stress: Association with Health Symptoms

Cumulative adversity (CA) increases stress sensitivity and risk of adverse health outcomes. However, neural mechanisms underlying these associations in humans remain unclear. To understand neural responses underlying the link between CA and adverse health symptoms, the current study assessed brain activity during stress and neutral-relaxing states in 75 demographically matched, healthy individuals with high, mid, and low CA (25 in each group), and their health symptoms using the Cornell Medical Index. CA was significantly associated with greater adverse health symptoms (P=0.01) in all participants. Functional magnetic resonance imaging results indicated significant associations between CA scores and increased stress-induced activity in the lateral prefrontal cortex, insula, striatum, right amygdala, hippocampus, and temporal regions in all 75 participants (p<0.05, whole-brain corrected). In addition to these regions, the high vs low CA group comparison revealed decreased stress-induced activity in the medial orbitofrontal cortex (OFC) in the high CA group (p<0.01, whole-brain corrected). Specifically, hypoactive medial OFC and hyperactive right hippocampus responses to stress were each significantly associated with greater adverse health symptoms (p<0.01). Furthermore, an inverse correlation was found between activity in the medial OFC and right hippocampus (p=0.01). These results indicate that high CA sensitizes limbic–striatal responses to acute stress and also identifies an important role for stress-related medial OFC and hippocampus responses in the effects of CA on increasing vulnerability to adverse health consequences.

The neurobiology of alcohol craving and relapse

A major block to recovery from alcoholism is substantial alcohol craving and the chronic relapsing nature of the illness. This chapter reviews relevant structural and functional neuroimaging studies and discusses neural mechanisms underlying alcohol craving and relapse in the context of influential risk factors (i.e., alcohol, alcohol cue, and stress). Review of neuroimaging studies suggests that neuroadaptations in the cortico-striatal-limbic circuit encompassing the medial prefrontal cortex, orbitofrontal cortex, anterior cingulate cortex, striatum, and amygdala significantly contribute to overwhelming alcohol craving and early relapse after a period of abstinence. The cortico-striatal-limbic circuit plays an important role in the modulation of emotion, reward, and decision making. As functional and structural chronic alcohol-related neuroadaptations are consistently reported in this circuit, it is likely that sensitization of this circuit from continued alcohol abuse may contribute to high alcohol craving and early relapse via impairments in the prefrontal executive function related to emotion regulation and decision making. This vulnerable neurobiologic state may be manifested as compulsive craving and intense urge to resume alcohol drinking in the face of environmental risk factors, including alcohol, alcohol cue, or stressful live events.

Neural correlates of stress and favorite‐food cue exposure in adolescents: A functional magnetic resonance imaging study

Adolescence is a critical period of neurodevelopment for stress and appetitive processing, as well as a time of increased vulnerability to stress and engagement in risky behaviors. This study was conducted to examine brain activation patterns during stress and favorite‐food‐cue experiences relative to a neutral‐relaxing condition in adolescents. Functional magnetic resonance imaging was employed using individualized script‐driven guided imagery to compare brain responses with such experiences in 43 adolescents. Main effects of condition and gender were found, without a significant gender‐by‐condition interaction. Stress imagery, relative to neutral, was associated with activation in the caudate, thalamus, left hippocampus/parahippocampal gyrus, midbrain, left superior/middle temporal gyrus, and right posterior cerebellum. Appetitive imagery of favorite food was associated with caudate, thalamus, and midbrain activation compared with the neutral‐relaxing condition. To understand neural correlates of anxiety and craving, subjective (self‐reported) measures of stress‐induced anxiety and favorite‐food‐cue‐induced craving were correlated with brain activity during stress and appetitive food‐cue conditions, respectively. High self‐reported stress‐induced anxiety was associated with hypoactivity in the striatum, thalamus, hippocampus, and midbrain. Self‐reported favorite‐food‐cue‐induced craving was associated with blunted activity in cortical‐striatal regions, including the right dorsal and ventral striatum, medial prefrontal cortex, motor cortex, and left anterior cingulate cortex. These findings in adolescents indicate the activation of predominantly subcortical‐striatal regions in the processing of stressful and appetitive experiences and link hypoactive striatal circuits to self‐reported stress‐induced anxiety and cue‐induced favorite‐food craving. Hum Brain Mapp 34:2561–2573, 2013.

Leptin Is Associated With Exaggerated Brain Reward and Emotion Responses to Food Images in Adolescent Obesity

OBJECTIVE In the U.S., an astonishing 12.5 million children and adolescents are now obese, predisposing 17% of our nation’s youth to metabolic complications of obesity, such as type 2 diabetes (T2D). Adolescent obesity has tripled over the last three decades in the setting of food advertising directed at children. Obese adults exhibit increased brain responses to food images in motivation-reward pathways. These neural alterations may be attributed to obesity-related metabolic changes, which promote food craving and high-calorie food (HCF) consumption. It is not known whether these metabolic changes affect neural responses in the adolescent brain during a crucial period for establishing healthy eating behaviors. RESEARCH DESIGN AND METHODS Twenty-five obese (BMI 34.4 kg/m2, age 15.7 years) and fifteen lean (BMI 20.96 kg/m2, age 15.5 years) adolescents underwent functional MRI during exposure to HCF, low-calorie food (LCF), and nonfood (NF) visual stimuli 2 h after isocaloric meal consumption. RESULTS Brain responses to HCF relative to NF cues increased in obese versus lean adolescents in striatal-limbic regions (i.e., putamen/caudate, insula, amygdala) (P < 0.05, family-wise error [FWE]), involved in motivation-reward and emotion processing. Higher endogenous leptin levels correlated with increased neural activation to HCF images in all subjects (P < 0.05, FWE). CONCLUSIONS This significant association between higher circulating leptin and hyperresponsiveness of brain motivation-reward regions to HCF images suggests that dysfunctional leptin signaling may contribute to the risk of overconsumption of these foods, thus further predisposing adolescents to the development of obesity and T2D.

Dynamic neural activity during stress signals resilient coping

Significance We live in a time of increasing terror, stress, and trauma, and yet humans show a remarkable ability to cope under high stress states. How the brain supports such active resilient coping is not well-understood. Findings showed high stress levels are accompanied by dynamic brain signals in circuits representing the stress reaction, adaptation, and behavioral control responses. In addition, a ventromedial prefrontal cortical region showed initial decreases in brain activation, but then mobilized with increased activation, and this dynamic change was correlated with active coping. Conversely, individuals who failed to show such “neuroflexibility” in this specific ventromedial prefrontal region reported higher maladaptive coping behaviors. Findings suggest that strategies to promote such neuroflexibility under stress may increase stress resilience in humans. Active coping underlies a healthy stress response, but neural processes supporting such resilient coping are not well-known. Using a brief, sustained exposure paradigm contrasting highly stressful, threatening, and violent stimuli versus nonaversive neutral visual stimuli in a functional magnetic resonance imaging (fMRI) study, we show significant subjective, physiologic, and endocrine increases and temporally related dynamically distinct patterns of neural activation in brain circuits underlying the stress response. First, stress-specific sustained increases in the amygdala, striatum, hypothalamus, midbrain, right insula, and right dorsolateral prefrontal cortex (DLPFC) regions supported the stress processing and reactivity circuit. Second, dynamic neural activation during stress versus neutral runs, showing early increases followed by later reduced activation in the ventrolateral prefrontal cortex (VLPFC), dorsal anterior cingulate cortex (dACC), left DLPFC, hippocampus, and left insula, suggested a stress adaptation response network. Finally, dynamic stress-specific mobilization of the ventromedial prefrontal cortex (VmPFC), marked by initial hypoactivity followed by increased VmPFC activation, pointed to the VmPFC as a key locus of the emotional and behavioral control network. Consistent with this finding, greater neural flexibility signals in the VmPFC during stress correlated with active coping ratings whereas lower dynamic activity in the VmPFC also predicted a higher level of maladaptive coping behaviors in real life, including binge alcohol intake, emotional eating, and frequency of arguments and fights. These findings demonstrate acute functional neuroplasticity during stress, with distinct and separable brain networks that underlie critical components of the stress response, and a specific role for VmPFC neuroflexibility in stress-resilient coping.

Neural correlates of preparatory and regulatory control over positive and negative emotion

This study used functional magnetic resonance imaging to investigate brain activation during preparatory and regulatory control while participants (N = 24) were instructed either to simply view or decrease their emotional response to, pleasant, neutral or unpleasant pictures. A main effect of emotional valence on brain activity was found in the right precentral gyrus, with greater activation during positive than negative emotion regulation. A main effect of regulation phase was evident in the bilateral anterior prefrontal cortex (PFC), precuneus, posterior cingulate cortex, right putamen and temporal and occipital lobes, with greater activity in these regions during preparatory than regulatory control. A valence X regulation interaction was evident in regions of ventromedial PFC and anterior cingulate cortex, reflecting greater activation while regulating negative than positive emotion, but only during active emotion regulation (not preparation). Conjunction analyses revealed common brain regions involved in differing types of emotion regulation including selected areas of left lateral PFC, inferior parietal lobe, temporal lobe, right cerebellum and bilateral dorsomedial PFC. The right lateral PFC was additionally activated during the modulation of both positive and negative valence. Findings demonstrate significant modulation of brain activity during both preparation for, and active regulation of positive and negative emotional states.