Brain imaging demonstrates a reduced neural impact of eating in obesity

Abstract

Objective We investigated functional brain response differences to food in women with either BMI <25kg/m2 (lean) or >35kg/m2 (severe obesity). Methods Thirty women 18-65 years old from academic medical centers participated. Baseline brain perfusion was measured with arterial spin labeling. Brain activity was measured via blood-oxygen-level-dependent functional magnetic resonance imaging (fMRI) in response to food cues, and appeal to cues rated. Subjective hunger/fullness was reported pre- and post-imaging. After a standard meal, measures were repeated. Results When fasting, brain perfusion did not differ significantly between groups; and both groups significantly increased activity in the neo- and limbic cortices and midbrain compared to baseline (p<0.05, family-wise-error whole-brain corrected). Once fed, the lean group showed significantly decreased activation in these areas, especially the limbic cortex, while the group with severe obesity showed no such decreases (p<0.05, family-wise-error whole-brain corrected). After eating, appeal ratings of food decreased only in lean women. Within groups, hunger decreased (p<0.001) and fullness increased (p<0.001) fasted to fed. Conclusion While fasting, brain response to food cues in women did not differ significantly despite BMI. After eating, brain activity quickly diminished in lean women but remained elevated in women with severe obesity. These brain activation findings confirm previous studies.

The influence of obesity on cerebral blood flow in young adults using arterial spin labeling MRI

“…A similar design has been discussed in one previous study. 15 The researchers' finding that no significant differences existed in CBF between lean and obese groups was inconsistent with our result. This divergence may potentially be attributed to the differences in adipose tissue.…”

“…This divergence may potentially be attributed to the differences in adipose tissue. In this study, 90% of the participants are male, while all participants in the aforementioned study 15 are female. Although global studies show that the prevalence of obesity is higher in women than in men, 39 men have significantly more visceral adipose tissue (VAT) than women while females have higher amounts of subcutaneous adipose tissue (SAT) than BMI-matched men.…”

“…CBF is not considered a new approach, and alterations in CBF have been observed in cognition decline, 9 neurodegenerative diseases such as Alzheimer's disease, 10 and mental illnesses. 11 In terms of obesity, early works using single-photon emission computed tomography (SPECT) 12 and ultrasound 13 demonstrated that high BMI is associated with a reduction in brain perfusion; meanwhile, arterial spin labeling (ASL) MRI has also received increasing attention for assessing the impact of obesity on brain perfusion, [14][15][16][17] with the advantages of no radiation burden and user independence. Information obtained by analyzing CBF can help to advance our understanding of obesity, beyond the knowledge obtained from analyzing brain structure.…”

“…However, one overlooked aspect in these earlier studies is that the majority of studies on obesity have covered life stages from adolescence to old age, 2,12,15,18 and only a few studies have specifically focused on an early adulthood sample. Therefore, the central goal of this study was to investigate the potential effect of obesity on brain perfusion in a cohort aged 20-30 years in terms of both global and regional analyses by using the ASL MRI technique.…”

Double jeopardy: Comorbid obesity and cigarette smoking are linked to neurobiological alterations in inhibitory control during smoking cue exposure

“…It was not a prospective examination, and as such, we were unable to analyze additional variables of interest that might specifically be relevant to a population with obesity, such as hunger ratings, weight loss, dieting, weight stability/suppression, or dietary intake. Hunger state has been shown to differentially influence response to food reward in lean participants and those with obesity and, thus, may have had a differential effect on response to smoking cues. Unfortunately, we lacked adequate measures to control for hormonal status among female participants.…”