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Obese teens with high leptin levels have increased brain response to food cues
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In adolescents, obesity and high circulating leptin levels appear to be significantly associated with increased neural responses to images of high-calorie foods, according to recent findings.
In the study, researchers evaluated 25 adolescents with BMI > the 95th percentile (obese cohort) and 15 teens with BMI > 25th to <75th percentile (lean cohort). The participants were between the ages of 12 and 17, otherwise healthy, and weight-stable. The researchers asked participants to refrain from strenuous physical activity for 2 weeks prior to the start of the study.
Based on 3-day food records chronicled by all participants, there was no statistically significant difference in kilocalories consumed between obese and lean participants.
At one study visit, researchers took anthropometric measurements and conducted a frequently sampled oral glucose tolerance test (OGTT). A fasting blood sample was also taken and assessed by radioimmunoassay.
At a subsequent visit, participants underwent a functional MRI (fMRI) scan of the brain while viewing a series of 126 photographs (42 high calorie foods [HCFs], 42 low-calorie foods [LCFs] and 42 non-food [NF] images, such as bicycles or books). All participants had eaten a mixed meal 2 hours prior to ensure uniform levels of satiety.
The researchers found that compared with the lean adolescents, the obese adolescents had increased neural responses in the striatal-limbic regions of the brain when viewing the HCF images as opposed to the NF images (P<.05). These regions, which include the putamen/caudate, insula and amygdala, pertain to motivation/reward and emotion. Additionally, the researchers observed an association between higher native leptin levels and increased brain response to HCF images in all participants (P<.05).
“Our data suggest that obese adolescents exhibit exaggerated neural responses in striatal-limbic regions to images of HCF that are associated with circulating leptin elevations,” the researchers wrote. “Dysregulation of brain regions influencing reward motivation and emotion may increase the drive to eat HCF and decrease control over consumption of such foods, particularly in obese adolescents who may be particularly vulnerable to food cues.”
Disclosure: Please see the full study for a list of relevant disclosures.
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