Who gains? Genetic and neurophysiological correlates of BMI gain upon college entry in women

Converging vulnerability factors for compulsive food and drug use

Highly palatable foods and substance of abuse have intersecting neurobiological, metabolic and behavioral effects relevant for understanding vulnerability to conditions related to food (e.g., obesity, binge eating disorder) and drug (e.g., substance use disorder) misuse. Here, we review data from animal models, clinical populations and epidemiological evidence in behavioral, genetic, pathophysiologic and therapeutic domains. Results suggest that consumption of highly palatable food and drugs of abuse both impact and conversely are regulated by metabolic hormones and metabolic status. Palatable foods high in fat and/or sugar can elicit adaptation in brain reward and withdrawal circuitry akin to substances of abuse. Intake of or withdrawal from palatable food can impact behavioral sensitivity to drugs of abuse and vice versa. A robust literature suggests common substrates and roles for negative reinforcement, negative affect, negative urgency, and impulse control deficits, with both highly palatable foods and substances of abuse. Candidate genetic risk loci shared by obesity and alcohol use disorders have been identified in molecules classically associated with both metabolic and motivational functions. Finally, certain drugs may have overlapping therapeutic potential to treat obesity, diabetes, binge-related eating disorders and substance use disorders. Taken together, data are consistent with the hypotheses that compulsive food and substance use share overlapping, interacting substrates at neurobiological and metabolic levels and that motivated behavior associated with feeding or substance use might constitute vulnerability factors for one another. This article is part of the special issue on 'Vulnerabilities to Substance Abuse'.

HIV/AIDS and an overweight body mass are associated with excessive intra-individual variability in response preparation

Factors other than HIV/AIDS may influence the cognitive function of patients living with this disease. The present study tested the influence of a common comorbid problem-an overweight body mass. It also examined intra-task variabilities in performance and brain activation as potentially more sensitive indicators of dysfunction than their mean levels. One-hundred seventy-eight participants were recruited and categorized by HIV-1 serostatus (-/+) and body mass (BMI < 26/≥ 26 kg/m2). They performed a simple time estimation task during which response time accuracy and electroencephalographic readiness potentials were recorded. A few hours later, they completed a battery of tests measuring balance and gait. The analyses revealed an advantage of variability over the mean in differentiating groups: the presence of HIV-1 and an overweight body mass were independently and additively associated with greater variability across trials in readiness potential amplitude and response accuracy. The analysis also showed that intra-task variability in the readiness potential, but not in response accuracy, was predictive of decrements in single and tandem leg balance and gait velocity. The present findings suggest that an elevated body mass is associated with, and may contribute to, problems in brain function and motor behavior experienced by patients in the current era. The findings recommend a careful consideration of the manner in which these problems are measured. When the problems are episodic and subtle, measures of central tendency may be less than ideal.

The value of instability: an investigation of intrasubject variability in brain activity among obese adolescent girls

BACKGROUND

The present study investigated the value of intrasubject variability (ISV) as a metric for revealing differences in cognition and brain activation associated with an obese versus lean body mass.

METHODS

Ninety-six adolescents with a lean body mass (body mass index (BMI) percentile=5-85), and 92 adolescents with an obese body mass (BMI percentile ⩾95), performed two tasks (Stroop and Go/No-Go) challenging response inhibition skills. The s.d. values and averages of their reaction time and P300 electroencephalographic responses to task stimuli were computed across trials.

RESULTS

During the Go/No-Go task, the reaction times of subjects with an obese body mass were more variable than those of their lean body mass peers. Accompanying the greater ISV in reaction times was a group difference in P300 amplitude ISV in the opposite direction across both tasks. The effect sizes associated with these group differences in ISV were marginally greater than the effect sizes for the comparisons of the group means.

CONCLUSIONS

ISV may be superior to the mean as a tool for differentiating groups without significant cognitive impairment. The co-occurrence of reduced ISV in P300 amplitude and elevated ISV in reaction time may indicate a constraint among obese adolescent girls in the range of information processing strategies and neural networks that can compete to optimize response output. It remains to be determined whether this decrement in neural plasticity has implications for their problem solving skills as well as their response to weight management interventions.

Visual illusions and inattention: Their association with adiposity among adolescent girls

The Delboeuf concentric circle illusion is frequently invoked as an explanation for the hypothesized association between dinner plate size and overeating. We examined its association with adiposity among 162 girls, aged 14-18 years. We also examined the association of adiposity with neural and behavioral responses during a separate visual discrimination task. The analysis showed that girls with a body mass index percentile ≥ 85, or with greater triceps skinfold thickness, exhibited less sensitivity to the Delboeuf illusion than girls with normal adiposity. The excess adiposity group also exhibited significantly smaller electroencephalographic responses and more errors during the separate visual discrimination task. In combination, the findings from the two tasks suggest that girls with an elevated body mass are less sensitive to visual cues in their environment. The implications of these findings for weight loss education should be considered.