Systemic inflammation mediates the negative relationship between visceral adiposity and cognitive control

Interactions between age, sex and visceral adipose tissue on brain ageing

AIM

To examine the associations between visceral adipose tissue (VAT) and brain structural measures at midlife and explore how these associations may be affected by age, sex and cardiometabolic factors.

METHODS

We used abdominal and brain magnetic resonance imaging data from a population-based cohort of people at midlife in the UK Biobank. Regression modelling was applied to study associations of VAT volume with total brain volume (TBV), grey matter volume (GMV), white matter volume, white matter hyperintensity volume (WMHV) and total hippocampal volume (THV), and whether these associations were altered by age, sex or cardiometabolic factors.

RESULTS

Complete data were available for 17 377 participants (mean age 63 years, standard deviation = 12, 53% female). Greater VAT was associated with lower TBV, GMV and THV (P < .001). We found an interaction between VAT and sex on TBV (P < .001), such that the negative association of VAT with TBV was greater in men (β = -2.89, 95% confidence interval [CI] -2.32 to -10.15) than in women (β = -1.32, 95% CI -0.49 to -3.14), with similar findings for GMV. We also found an interaction between VAT and age (but not sex) on WMHV (P < .001). The addition of other cardiometabolic factors or measures of physical activity resulted in little change to the models.

CONCLUSIONS

VAT volume is associated with poorer brain health in midlife and this relationship is greatest in men and those at younger ages.

Association between visceral adiposity and generalized anxiety disorder (GAD)

BACKGROUND AND OBJECTIVES

Due to an increased rate of inflammation in generalized anxiety disorder (GAD), insight into the mediating factors in the onset and recurrence of the inflammatory response can help to achieve novel treatments for alleviating the risk of GAD. In the current study, we aimed to evaluate the possible relationship between visceral adipose tissue (VAT) as an important intermediary in inflammation pathways and GAD in participants of the Employees' Health Cohort Study of Iran (EHCSIR).

METHOD

We analyzed the data from 3889 included participants aged > 18 years in the EHCSIR study, which were collected from 2017 to 2020. Lifetime and 12-month GAD were assessed using the Composite International Diagnostic Interview (CIDI-2.1) questionnaire. The adjusted prevalence ratio was computed to evaluate the association between GAD and visceral adiposity index (VAI), GAD and visceral fat area (VFA), GAD and body mass index (BMI) and ultimately GAD and waist circumference (WC) in males and females using STATA software.

RESULTS

Log-binomial analysis showed a higher prevalence ratio of 12-month GAD associated with VFA in women [PR: 1.42, CI: 1.07-1.87, P: 0.015]. The prevalence of lifetime GAD was higher in obese women (BM1 > 30) [PR: 2.35, CI: 1.07-5.13, P:0.03] than in women with normal BMI. Women with higher VAI were also significantly more likely to suffer lifetime GAD [PR: 1.25, CI: 1.05]. 1.48, P:0.01]. In males, the prevalence of lifetime diagnosed GAD per 1 standard deviation increase in VFA was 0.65 [CI: 0.46-0.91, P: 0.01].

CONCLUSION

Visceral adiposity as a positive agent was associated with GAD prevalence in women. The presence of GAD symptoms showed no relationship to VFA in men.

Higher visceral adipose tissue is associated with decreased memory suppression ability on food-related thoughts: A 1-year prospective ERP study

Memory about food and eating is crucial in regulating appetite and eating behaviors. Successfully stopping vivid imagination of delicious food could help reduce food craving and thus reduce the possibility of further intake. Memory inhibition is a cognitive process that involves intentional suppression of certain memories coming to consciousness. Successful memory suppression derives from inhibitory control. Although considerable work has consistently observed the impairment in motor or response inhibitory control among individuals with obesity, there has been a lack of investigation into the influence of bodyweight status on memory inhibitory control. To fill this gap, current study investigated behavioral and neurophysiological correlates of memory suppression in young women. Using Think/No-Think task and event-related potentials among 47 females, we found that participants with higher visceral adipose tissue (VAT) showed a tendency towards decreased suppression ability for memories related to food but not memories related to nonfood items. In depth analysis showed that decrease in the differences in P2 amplitudes between suppression vs. retrieval of food-related memories mediated the impairment of suppression ability by high VAT. We then tested whether individual differences in memory suppression ability as well as ERP correlates predicted future BMI or VAT change over 1-year follow-up. Results showed that P2 amplitudes when retrieving food-related memory could predict VAT change at 1-year follow-up among participants with healthy BMI. These observations suggest a hypersensitivity inference hypothesis underlying memory control impairments. To be specific, deficits in memory suppression may be in part resulted from elevated sensitivity to the cues coupling with food-related memory. It extends previous studies of memory suppression with food rewards and provides the first evidence to help understand the relationship between inhibitory control on food-related memory and obesity.

Adiposity as a risk factor for inflammatory bowel disease and the mediating effect of metabolic and inflammatory status: A population-based cohort study

BACKGROUND

To examine whether general and abdominal adiposity was a risk factor for the new-onset of inflammatory bowel disease (IBD) and the potential mediating effect of metabolic and inflammation status.

METHODS

A total of 492,998 individuals free of IBD recruited from 2006 to 2010 in the UK Biobank were included in our study, with ongoing follow-up linking to the health-related outcome. Multivariable Cox regression models were used to evaluate the associations between general adiposity (body mass index) and abdominal adiposity (waist circumference) and the subsequent risk of IBD and its subtype. We also investigated the potential mediating effects of metabolic and inflammation status by carrying out exploratory mediation analyses.

RESULTS

During a median follow-up of 12.5 years, we documented 2954 incident IBD cases (915 Crohn's disease [CD] and 2039 ulcerative colitis). After adjustment for important confounders, body mass index (hazard ratio [HR] highest quintile [Q5] vs. lowest quintile [Q1] = 1.18, 95% confidence interval [CI] 1.04-1.32; P-trend = 0.006) and waist circumference (HR Q5 vs. Q1  = 1.30, 95% CI 1.14-1.49; P-trend <0.001) showed a positive association with the risk of IBD. The associations were partially mediated by metabolic status (24%; 15%), C-reactive protein (36%; 19%) and inflammation score (82%; 46%).

CONCLUSIONS

Adiposity bore a risk factor for incident IBD, whereas unhealthy metabolism, especially inflammation, seemed to be an important intermediate condition between the association. Our findings provide evidence for possible mechanisms relating adiposity to IBD from an epidemiological perspective, and experimental studies are needed for further demonstration.

The association between regional adiposity, cognitive function, and dementia-related brain changes: a systematic review

Background

Adiposity has been previously associated with cognitive impairment and Alzheimer's disease and related disorders (ADRD). Body mass index (BMI) is the most common measure of global adiposity, but inconsistent results were found since it is a global measurement. BMI does not represent regional fat distribution which differs between sexes, race, and age. Regional fat distribution may contribute differently to cognitive decline and Alzheimer's disease (AD)-related brain changes. Fat-specific targeted therapies could lead to personalized improvement of cognition. The goal of this systematic review is to explore whether regional fat depots, rather than central obesity, should be used to understand the mechanism underlying the association between adiposity and brain.

Methods

This systematic review included 33 studies in the English language, conducted in humans aged 18 years and over with assessment of regional adiposity, cognitive function, dementia, and brain measures. We included only studies that have assessed regional adiposity using imaging technics and excluded studies that were review articles, abstract only or letters to editor. Studies on children and adolescents, animal studies, and studies of patients with gastrointestinal diseases were excluded. PubMed, PsychInfo and web of science were used as electronic databases for literature search until November 2022.

Results

Based on the currently available literature, the findings suggest that different regional fat depots are likely associated with increased risk of cognitive impairment, brain changes and dementia, especially AD. However, different regional fat depots can have different cognitive outcomes and affect the brain differently. Visceral adipose tissue (VAT) was the most studied regional fat, along with liver fat through non-alcoholic fatty liver disease (NAFLD). Pancreatic fat was the least studied regional fat.

Conclusion

Regional adiposity, which is modifiable, may explain discrepancies in associations of global adiposity, brain, and cognition. Specific regional fat depots lead to abnormal secretion of adipose factors which in turn may penetrate the blood brain barrier leading to brain damage and to cognitive decline.

Weight status impacts children's incidental statistical learning

The expanding literature investigating the cognitive effects of childhood weight status has not included examinations of incidental statistical learning, the process by which children unintentionally acquire knowledge about patterns in their environments, despite evidence that it underlies many higher-level information processing capabilities. In the present study, we measured event-related potentials (ERPs) while school-aged participants completed a variation of an oddball task in which stimuli predicted the appearance of a target. Children were asked to respond to the target but were not given any information about the existence of predictive dependencies. We found that children with a healthy weight status had larger P3 amplitudes in response to the predictors that were most meaningful in completing the task, a finding that may suggest optimized learning mechanisms influenced by weight status. These findings offer an important first step to understanding how healthy lifestyle factors may influence incidental statistical learning.