Dysfunctional involvement of emotion and reward brain regions on social decision making in excess weight adolescents.

Obese adolescents suffer negative social experiences, but no studies have examined whether obesity is associated with dysfunction of the social brain or whether social brain abnormalities relate to disadvantageous traits and social decisions. We aimed at mapping functional activation differences in the brain circuitry of social decision making in adolescents with excess versus normal weight, and at examining whether these separate patterns correlate with reward/punishment sensitivity, disordered eating features, and behavioral decisions. In this fMRI study, 80 adolescents aged 12 to 18 years old were classified in two groups based on age adjusted body mass index (BMI) percentiles: normal weight (n = 44, BMI percentiles 5th-84th) and excess weight (n = 36, BMI percentile ≥ 85th). Participants were scanned while performing a social decision-making task (ultimatum game) in which they chose to "accept" or "reject" offers to split monetary stakes made by another peer. Offers varied in fairness (Fair vs. Unfair) but in all cases "accepting" meant both players win the money, whereas "rejecting" meant both lose it. We showed that adolescents with excess weight compared to controls display significantly decreased activation of anterior insula, anterior cingulate, and midbrain during decisions about Unfair versus Fair offers. Moreover, excess weight subjects show lower sensitivity to reward and more maturity fears, which correlate with insula activation. Indeed, blunted insula activation accounted for the relationship between maturity fears and acceptance of unfair offers. Excess weight adolescents have diminished activation of brain regions essential for affective tracking of social decision making, which accounts for the association between maturity fears and social decisions.

Effects of a multicomponent behavioral intervention on impulsivity and cognitive deficits in adolescents with excess weight.

The aim of this study was to explore the effects of a multidisciplinary behavioral intervention including cognitive behavioral therapy, structured physical activity, and dietary counseling on impulsive personality and cognitive skills and subsequent BMI loss in excess weight adolescents. Forty-two adolescents with excess weight (14 males and 28 females, range 12-17 years), as defined by the International Obesity Task Force Criteria, participated in our study. We used a longitudinal observational design with two assessments: before and after treatment. We collected baseline measures of impulsive personality (UPPS-P scale), cognitive performance (letter number sequencing, Stroop and Iowa gambling task), and biometric parameters. After 12 weeks of intervention, parallel measures were used to determine whether treatment-induced changes in impulsivity and cognition predicted changes in BMI. BMI showed a statistically significant reduction after treatment [from mean (SD) 29.36 (4.51) to 27.31 (4.41), Cohen's d=0.5]. Greater reductions in negative urgency (negative-emotion-driven impulsivity) and greater improvement in cognitive inhibitory control skills were associated with greater reductions in BMI. Because the design was correlational and lacked a control group, future studies should clarify whether these associations reflect a causal effect or just overlapping improvements associated with a third variable (e.g. increases in attention procurement or motivation).

Decreased insular and increased midbrain activations during decision-making under risk in adolescents with excess weight.

OBJECTIVE: Functional magnetic resonance imaging (fMRI) was used to explore the brain substrates of decisions under risk in excess weight adolescents. Decreased activations of the brain regions signaling risk (orbitofrontal cortex [OFC], insula) were expected during anticipation of higher rewards and increased activations of the brain regions involved in reward processing (OFC, striatum) were expected after reward receipt in excess weight adolescents compared to normal weight controls. DESIGN AND METHODS: Fifty-two adolescents (age range 12-17), classified in three groups as a function of BMI: obese (n = 21), overweight (n = 15), or normal weight (n = 16) performed the Risky-Gains task as described by Paulus et al. in the fMRI scanner. RESULTS: Excess weight adolescents, compared to normal weight controls, showed decreased left insular and increased midbrain activations during anticipation of risky choices. In addition, excess weight adolescents showed increased activations of the inferior frontal gyrus, parahippocampus, thalamus, and posterior brain regions after reward receipt. CONCLUSIONS: Adolescents with excess weight showed reduced activations in brain regions signaling risk and increased activations in regions signaling reward during anticipation of decisions involving risk and reward. In addition, post-decision reward outcomes produced increased activations of regions involved in emotional salience in excess weight adolescents versus controls.

BMI predicts emotion-driven impulsivity and cognitive inflexibility in adolescents with excess weight.

Adolescent obesity is increasingly viewed as a brain-related dysfunction, whereby reward-driven urges for pleasurable foods "hijack" response selection systems, such that behavioral control progressively shifts from impulsivity to compulsivity. In this study, we aimed to examine the link between personality factors (sensitivity to reward (SR) and punishment (SP), BMI, and outcome measures of impulsivity vs. flexibility in--otherwise healthy--excessive weight adolescents. Sixty-three adolescents (aged 12-17) classified as obese (n = 26), overweight (n = 16), or normal weight (n = 21) participated in the study. We used psychometric assessments of the SR and SP motivational systems, impulsivity (using the UPPS-P scale), and neurocognitive measures with discriminant validity to dissociate inhibition vs. flexibility deficits (using the process-approach version of the Stroop test). We tested the relative contribution of age, SR/SP, and BMI on estimates of impulsivity and inhibition vs. switching performance using multistep hierarchical regression models. BMI significantly predicted elevations in emotion-driven impulsivity (positive and negative urgency) and inferior flexibility performance in adolescents with excess weight--exceeding the predictive capacity of SR and SP. SR was the main predictor of elevations in sensation seeking and lack of premeditation. These findings demonstrate that increases in BMI are specifically associated with elevations in emotion-driven impulsivity and cognitive inflexibility, supporting a dimensional path in which adolescents with excess weight increase their proneness to overindulge when under strong affective states, and their difficulties to switch or reverse habitual behavioral patterns.

Brain structural correlates of reward sensitivity and impulsivity in adolescents with normal and excess weight.

INTRODUCTION: Neuroscience evidence suggests that adolescent obesity is linked to brain dysfunctions associated with enhanced reward and somatosensory processing and reduced impulse control during food processing. Comparatively less is known about the role of more stable brain structural measures and their link to personality traits and neuropsychological factors on the presentation of adolescent obesity. Here we aimed to investigate regional brain anatomy in adolescents with excess weight vs. lean controls. We also aimed to contrast the associations between brain structure and personality and cognitive measures in both groups. METHODS: Fifty-two adolescents (16 with normal weight and 36 with excess weight) were scanned using magnetic resonance imaging and completed the Sensitivity to Punishment and Sensitivity to Reward Questionnaire (SPSRQ), the UPPS-P scale, and the Stroop task. Voxel-based morphometry (VBM) was used to assess possible between-group differences in regional gray matter (GM) and to measure the putative differences in the way reward and punishment sensitivity, impulsivity and inhibitory control relate to regional GM volumes, which were analyzed using both region of interest (ROI) and whole brain analyses. The ROIs included areas involved in reward/somatosensory processing (striatum, somatosensory cortices) and motivation/impulse control (hippocampus, prefrontal cortex). RESULTS: Excess weight adolescents showed increased GM volume in the right hippocampus. Voxel-wise volumes of the second somatosensory cortex (SII) were correlated with reward sensitivity and positive urgency in lean controls, but this association was missed in excess weight adolescents. Moreover, Stroop performance correlated with dorsolateral prefrontal cortex volumes in controls but not in excess weight adolescents. CONCLUSION: Adolescents with excess weight have structural abnormalities in brain regions associated with somatosensory processing and motivation.