Getting to the heart of food craving with resting heart rate variability in adolescents.

BACKGROUND: There is an epidemic of obesity in children and adolescents. Research into the self-regulatory factors that drive eating behavior is of critical importance. Food craving contributes to overeating and difficulty with weight loss and is strongly correlated with self-regulation. High-frequency heart rate variability (HF HRV) reflects parasympathetic activity and is positively associated with self-regulation. Few studies of HF HRV and food craving have been conducted in adolescents. The current study examined the association between HF HRV and food craving in a large-scale sample of healthy adolescents. METHOD: Electrocardiogram (ECG) was recorded in 134 healthy adolescents aged 10-17 during a 7-min resting state. Participants also completed the Food Craving Questionnaire-Trait (FCQ-T). The relative power of HF HRV was calculated. Association between HF HRV and food craving was examined in the context of sex and age. Next, the relative significance of all food craving subscales was considered in relation to HF HRV. RESULTS: HF HRV was inversely correlated with food craving, taking into account sex and age. Considering all the subscales of FCQ-T in relation to HF HRV, the "lack of control over eating" subscale accounted for the most significant variance. CONCLUSION: This was the first study to evaluate resting HRV and eating behaviors in a large-scale adolescent sample. HF HRV was negatively associated with food craving, with lower HF HRV correlating with higher food craving, especially in the context of diminished control over eating. HF HRV could be a potential biomarker for food craving and food-related self-regulation capacity, and therefore may aid weight management interventions.

An inactive control of the 'Trier Social Stress Test' for Youth 10-17 years: Neuroendocrine, cardiac, and subjective responses.

The Trier Social Stress Test for children (TSST-C) adapted from TSST is one of the most commonly used laboratory paradigms for investigating the effects of stress on cognitive, affective and physiological responses in children and adolescents. Considering that laboratory procedures generate a significant amount of stress to children and adolescents, even in the absence of a stress paradigm, it is important to validate TSST-C against an inactive control condition in which the stress components were absent. Using a randomized design, we tested an inactive control condition, which replaced the TSST-C with a benign video clip (nature scenes viewed while standing), thus removing the stress associated components of the TSST-C. Eighty-eight youth between the ages of 10 and 17 years were randomly assigned to complete the TSST-C or the Inactive Control (IC). Subjective anxiety rating, salivary cortisol, systolic and diastolic blood pressure, and heart rate were collected at eight time points. Subjects in the Inactive Control condition showed no significant changes in blood pressure and heart rate, and decreased anxiety rating and salivary cortisol level throughout the study. Subjects in the stress condition (TSST-C) showed increased anxiety ratings, salivary cortisol, systolic and diastolic blood pressure, and heart rate immediately following TSST-C stress induction. Our findings validated that the TSST-C induced a systemic stress response, and that the Inactive Control can be a promising standardized control condition for the TSST-C and a tool for future psychobiological research. Our results also showed that anxiety reactivity decreased with age while HR reactivity increased with age. Cortisol reactivity did not fall in a linear relationship with age but rather via a quadratic curve, suggesting the mid-age adolescents had the highest cortisol responses to stress compared to their younger and older peers, potentially due to a dual factor of pubertal development and self-control and emotion regulation capacity.

High frequency heart-rate variability predicts adolescent depressive symptoms, particularly anhedonia, across one year.

BACKGROUND: Few prospective studies examine the link between lower heart rate variability (HRV) and depression symptoms in adolescents. A recent animal model specifically links HRV to anhedonia, suggesting a potential translational model for human research. METHOD: We investigated the association between spectral measures of resting HRV and depressive symptoms measured one year later, among 73 adolescents, aged 11-18 years. We evaluated (1) the predictive power of relative high frequency (HF) HRV, relative low frequency (LF) and relative very low frequency (VLF) HRV for depressive symptoms; and (2) the relative strength of association between HF HRV and depressive symptomatology (anhedonia, negative mood, interpersonal problems, ineffectiveness, negative self-esteem). RESULTS: HF HRV significantly predicted self-reported depressive symptoms across one year, controlling for age, puberty and sex. HF HRV was most strongly associated with anhedonia one year later, after considering other facets of depressive symptomatology. CONCLUSIONS: Results provide support for the prospective relationship between relative HF HRV and depressive symptoms among adolescents across one year. Findings concur with rodent models that suggest a specific link between HF HRV and anhedonia. LIMITATIONS: We investigated relative spectral power HF HRV and depressive symptom dimensions. We cannot make strong claims about these associations in clinical depression. Physical activity levels could be controlled in future work.

A prospective study of severe irritability in youths: 2- and 4-year follow-up.

BACKGROUND: Severe, chronic irritability is receiving increased research attention, and is the cardinal symptom of a new diagnostic category, disruptive mood dysregulation disorder (DMDD). Although data from epidemiological community samples suggest that childhood chronic irritability predicts unipolar depression and anxiety in adulthood, whether these symptoms are stable and cause ongoing clinical impairment is unknown. The present study presents 4-year prospective and longitudinal diagnostic and impairment data on a clinical sample of children selected for symptoms of severe irritability (operationalized as severe mood dysregulation [SMD]). METHODS: Youth meeting criteria for SMD (n = 200) were evaluated at baseline using standard diagnostic methods. Two-year (n = 78) and 4-year (n = 46) follow-up diagnostic and clinical impairment ratings collected at 6-month intervals were completed with those youths enrolled in the study for a sufficient time. RESULTS: Although the number of youth meeting strict categorical SMD criteria declined over time (49 and 40% at 2 and 4 years, respectively), many individuals not meeting full criteria continued to display clinically significant irritability symptoms (2 years: 42%; 4 years: 37%). Impairment due to these irritability symptoms remained consistently in the moderate range on the Clinical Global Impressions Scale. CONCLUSIONS: By the 4-year follow-up, only 40% of youths meet strict SMD criteria; however, most continue to display clinically impairing symptoms and significant impairment warranting psychiatric treatment. These findings provide evidence for the course of irritability, with implications for DMDD. Future research with populations meeting DMDD criteria and followed through the ages of high risk for psychiatric diagnoses is necessary.

Parental-adolescent drug use discussions: physiological responses and associated outcomes.

PURPOSE: Although talking to youth about drugs is often recommended to parents, we know little about how parents actually discuss drugs with their children in the moment and how parental advice is linked to youth arousal and substance use. This study examined observed parental drug use advice and parenting behaviors during parent-adolescent drug use discussions and associations with adolescent physiological responses and substance use. METHODS: Fifty-eight 12-17 year olds and their primary caregivers participated in a laboratory session in which parents and youth discussed the topic of alcohol and/or drug use for 10 minutes. This discussion was videotaped and coded for drug use advice (rules against drug use, information on drug use consequences, scenarios or learning advice [discussing drug use scenarios and what the child has learned about drugs]) and general parenting behaviors (parental warmth and/or support, negative and/or critical parenting). Before, during, and after the discussions, adolescents' heart rate, blood pressure (BP), and salivary cortisol levels were assessed. RESULTS: Parental discussion of scenarios and/or learning was associated with lower adolescent BP responses to the discussions and lower likelihood of substance use. Parental discussion of rules against drug use was associated with higher heart rate and BP responses and greater likelihood of substance use. Criticism and/or negative parenting was associated with higher cortisol responses and greater likelihood of substance use at a trend level. CONCLUSIONS: Parenting characterized by greater discussion of drug use scenarios and less stating of rules against drug use and criticism may make youth feel more comfortable and be linked to lower substance use.

Attention bias to threat faces in severe mood dysregulation.

BACKGROUND: We used a dot-probe paradigm to examine attention bias toward threat (i.e., angry) and happy face stimuli in severe mood dysregulation (SMD) versus healthy comparison (HC) youth. The tendency to allocate attention to threat is well established in anxiety and other disorders of negative affect. SMD is characterized by the negative affect of irritability, and longitudinal studies suggest childhood irritability predicts adult anxiety and depression. Therefore, it is important to study pathophysiologic connections between irritability and anxiety disorders. METHODS: SMD patients (N = 74) and HC youth (N = 42) completed a visual probe paradigm to assess attention bias to emotional faces. Diagnostic interviews were conducted and measures of irritability and anxiety were obtained in patients. RESULTS: SMD youth differed from HC youth in having a bias toward threatening faces (P < .01). Threat bias was positively correlated with the severity of the SMD syndrome and depressive symptoms; degree of threat bias did not differ between SMD youth with and without co-occurring anxiety disorders or depression. SMD and HC youth did not differ in bias toward or away from happy faces. CONCLUSIONS: SMD youth demonstrate an attention bias toward threat, with greater threat bias associated with higher levels of SMD symptom severity. Our findings suggest that irritability may share a pathophysiological link with anxiety and depressive disorders. This finding suggests the value of exploring further whether attention bias modification treatments that are effective for anxiety are also helpful in the treatment of irritability.

Reward feedback processing in children and adolescents: medial frontal theta oscillations.

We examined event-related electroencephalography (EEG) oscillations, including event-related spectral perturbations (ERSP) and intertrial coherence (ITC), to compare feedback processing during a chance-based reward vs. non-reward task in groups of 10-12-year-old (n=42), 13-14-year-old (n=34) and 15-17-year-olds (n=32). Because few, if any studies have applied these analytic methods to examine feedback processing in children or adolescents, we used a fine-grained approach that explored one half hertz by 16ms increments during feedback (no win vs. win events) in the theta (4-8Hz) frequency band. Complex wavelet frequency decomposition revealed that no win feedback was associated with enhanced theta power and phase coherence. We observed condition and age-based differences for both ERSP and ITC, with stronger effects for ITC. The transition from childhood to early adolescence (13-14yrs.) was a point of increased differentiation of ITC favoring no win vs. wins feedback and also compared to children or older adolescents, a point of heightened ITC for no win feedback (quadratic effect).

A developmental study of the feedback-related negativity from 10-17 years: age and sex effects for reward versus non-reward.

We employed event-related potentials to examine the feedback-related negativity (FRN), during a non-learning reward versus non-reward task. We compared 10-12-year-old, 13-14-year-old, and 15-17-year-old youth (n = 91). Age effects included a larger FRN for younger age groups, regardless of feedback type, and a decrease in peak latency for feedback, across age groups as a linear trend. Males showed larger responses irrespective of feedback type and longer latency for rewarded feedback. Source modeling revealed reward/non-reward differences in the anterior cingulate cortex (ACC) and orbitofrontal cortex, most strongly in the subgenual ACC. Males showed more subgenual ACC activity for feedback overall.

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.

Parent-adolescent conflict interactions and adolescent alcohol use.

OBJECTIVE: One important factor in adolescents' development of problem alcohol use is their family environment. Yet, the mechanisms that relate parenting to youth alcohol use are not well characterized. This study employed a naturalistic laboratory-based approach to observe parenting behaviors (support, structure, criticism) and adolescents' physiological and emotional responses to parent-adolescent interactions to examine associations with adolescent alcohol use. METHOD: Fifty eight 10-16year olds and their parents completed a 10minute Parent Adolescent Interaction Task (PAIT) in which they discussed a mutually highly-rated conflict topic. Parental support, structure, and criticism were coded from the interaction. Adolescents' heart rate (HR), blood pressure (BP), reported emotions, and salivary cortisol were assessed before, during, and after the interaction. RESULTS: Findings indicated that lower parental structure and support were associated with youth's greater diastolic BP and anger arousal in response to the PAIT. Furthermore, higher HR, systolic BP, and cortisol responses to the interaction were associated with youth's alcohol use. CONCLUSIONS: Findings suggest that heightened emotional and physiological responses to parent-adolescent conflict interactions in youth may be one pathway by which parenting is associated with adolescent alcohol use and risk for abuse.

Inhibitory motor control in response stopping and response switching.

While much is known about the neural regions recruited in the human brain when a dominant motor response becomes inappropriate and must be stopped, less is known about the regions that support switching to a new, appropriate, response. Using functional magnetic resonance imaging with two variants of the stop-signal paradigm that require either stopping altogether or switching to a different response, we examined the brain systems involved in these two forms of executive control. Both stopping trials and switching trials showed common recruitment of the right inferior frontal gyrus, presupplementary motor area, and midbrain. Contrasting switching trials with stopping trials showed activation similar to that observed on response trials (where the initial response remains appropriate and no control is invoked), whereas there were no regions that showed significantly greater activity for stopping trials compared with switching trials. These results show that response switching can be supported by the same neural systems as response inhibition, and suggest that the same mechanism of rapid, nonselective response inhibition that is thought to support speeded response stopping can also support speeded response switching when paired with execution of the new, appropriate, response.

Brain systems underlying response flexibility in healthy and bipolar adolescents: an event-related fMRI study.

OBJECTIVES: Previous studies have indicated abnormalities in response flexibility in pediatric bipolar disorder (BD). Dysfunction in response flexibility may contribute to the pattern of behavioral and emotional dysregulation that is characteristic of BD, since depressed and manic patients respond inflexibly to emotional stimuli (i.e., anhedonia in the case of depression or inappropriate positive affect in the case of mania). The present study was undertaken to determine if neuronal responses differed between BD and control subjects on a simple motor response flexibility task. METHODS: To elucidate the neural substrates mediating response flexibility in pediatric BD, we studied 25 youth with BD and 17 age-, gender- and IQ-matched controls (CON) as they performed the change task while undergoing event-related functional magnetic resonance imaging (fMRI). The change task is a new fMRI task that requires subjects to both inhibit and replace a prepotent motor response with another motor response after the initial response has been cued. RESULTS: On correctly performed change trials relative to correctly performed go trials, BD patients generated significantly more activity in the left dorsolateral prefrontal cortex (DLPFC) and in the primary motor cortex than did healthy controls, even though performance levels did not differ across groups. CONCLUSIONS: These results indicate that functional deficits within the left DLPFC may mediate deficits in response flexibility in pediatric BD. This deficit may extend beyond the realm of motor control and also affect emotion regulation.

Limbic hyperactivation during processing of neutral facial expressions in children with bipolar disorder.

Reflecting a paradigm shift in clinical neuroscience, many chronic psychiatric illnesses are now hypothesized to result from perturbed neural development. However, most work in this area focuses on schizophrenia. Here, we extend this paradigm to pediatric bipolar disorder (BD), thus demonstrating traction in the developmental psychobiology perspective. To study amygdala dysfunction, we examined neural mechanisms mediating face processing in 22 youths (mean age 14.21 +/- 3.11 yr) with BD and 21 controls of comparable age, gender, and IQ. Event-related functional MRI compared neural activation when attention was directed to emotional aspects of faces (hostility, subjects' fearfulness) vs. nonemotional aspects (nose width). Compared with controls, patients perceived greater hostility in neutral faces and reported more fear when viewing them. Also, compared with controls, patients had greater activation in the left amygdala, accumbens, putamen, and ventral prefrontal cortex when rating face hostility, and greater activation in the left amygdala and bilateral accumbens when rating their fear of the face. There were no between-group behavioral or neural differences in the nonemotional conditions. Results implicate deficient emotion-attention interactions in the pathophysiology of BD in youth and suggest that developmental psychobiology approaches to chronic mental illness have broad applicability.