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document
Selective insulin resistance in homeostatic and cognitive control brain areas in overweight and obese adults . OBJECTIVE Impaired brain insulin action has been linked to obesity , type 2 diabetes , and neurodegenerative diseases . To date , the central nervous effects of insulin in obese humans still remain ill defined , and no study thus far has evaluated the specific brain areas affected by insulin resistance . RESEARCH DESIGN AND METHODS In 25 healthy lean and 23 overweight/obese participants , we performed magnetic resonance imaging to measure cerebral blood flow ( CBF ) before and 15 and 30 min after application of intranasal insulin or placebo . Additionally , participants explicitly rated pictures of high-caloric savory and sweet food 60 min after the spray for wanting and liking . RESULTS In response to insulin compared with placebo , we found a significant CBF decrease in the hypothalamus in both lean and overweight/obese participants . The magnitude of this response correlated with visceral adipose tissue independent of other fat compartments . Furthermore , we observed a differential response in the lean compared with the overweight/obese group in the prefrontal cortex , resulting in an insulin-induced CBF reduction in lean participants only . This prefrontal cortex response significantly correlated with peripheral insulin sensitivity and eating behavior measures such as disinhibition and food craving . Behaviorally , we were able to observe a significant reduction for the wanting of sweet foods after insulin application in lean men only . CONCLUSIONS Brain insulin action was selectively impaired in the prefrontal cortex in overweight and obese adults and in the hypothalamus in participants with high visceral adipose tissue , potentially promoting an altered homeostatic set point and reduced inhibitory control contributing to overeating behavior .
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Intervention_Physical
magnetic resonance imaging
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Intervention_Pharmacological
intranasal insulin
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Intervention_Control
placebo
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Intervention_Pharmacological
insulin
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Intervention_Control
placebo
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Outcome_Physical
cerebral blood flow ( CBF )
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Outcome_Physical
CBF
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Outcome_Physical
insulin-induced CBF reduction
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Outcome_Physical
peripheral insulin sensitivity
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Outcome_Mental
eating behavior
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Outcome_Mental
wanting of sweet foods
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Participant_Condition
overweight and obese
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Participant_Age
adults
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Participant_Sample-size
25
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Participant_Sample-size
23