Assessing cognitive control and the reward system in overweight young adults using sensitivity to incentives and white matter integrity

Impact of Elevated Body Mass Index (BMI) on Hedonic Tone in Persons with Post-COVID-19 Condition: A Secondary Analysis

INTRODUCTION

The post-COVID-19 condition (PCC) is characterized by persistent, distressing symptoms following an acute COVID-19 infection. These symptoms encompass various domains, including hedonic tone, which is critical for overall well-being. Furthermore, obesity is both a risk factor for COVID-19 and PCC and associated with impaired hedonic tone. This study aims to investigate whether elevated body mass index (BMI) is associated with hedonic tone in persons with PCC.

METHODS

We perform a post hoc analysis of a randomized, double-blind, placebo-controlled clinical trial investigating the impact of vortioxetine on cognitive impairment in persons with PCC. Statistical analysis of baseline data using a generalized linear model was undertaken to determine the relationship of BMI to hedonic tone measured by Snaith-Hamilton Pleasure Scale (SHAPS) scores. The model was adjusted for covariates including age, sex, race, suspected versus confirmed COVID-19 cases, alcohol amount consumed per week, and annual household income.

RESULTS

The baseline data of 147 participants were available for analysis. BMI had a statistically significant positive association with baseline SHAPS total scores (β = 0.003, 95% CI [6.251E-5, 0.006], p = 0.045), indicating elevated BMI is associated with deficits in self-reported reward system functioning.

CONCLUSION

Higher BMI is associated with greater deficits in hedonic tone in persons with PCC, which may impact reward functioning processes such as reward prediction and processing. The mediatory effect of BMI on reward function underscores the need to investigate the neurobiologic interactions to elucidate preventative and therapeutic interventions for persons with PCC. Therapeutic development targeting debilitating features of PCC (e.g., motivation, cognitive dysfunction) could consider stratification on the basis of baseline BMI.

TRIAL REGISTRATION NUMBER

NCT05047952.

Brain functional and structural magnetic resonance imaging of obesity and weight loss interventions

Obesity has tripled over the past 40 years to become a major public health issue, as it is linked with increased mortality and elevated risk for various physical and neuropsychiatric illnesses. Accumulating evidence from neuroimaging studies suggests that obesity negatively affects brain function and structure, especially within fronto-mesolimbic circuitry. Obese individuals show abnormal neural responses to food cues, taste and smell, resting-state activity and functional connectivity, and cognitive tasks including decision-making, inhibitory-control, learning/memory, and attention. In addition, obesity is associated with altered cortical morphometry, a lowered gray/white matter volume, and impaired white matter integrity. Various interventions and treatments including bariatric surgery, the most effective treatment for obesity in clinical practice, as well as dietary, exercise, pharmacological, and neuromodulation interventions such as transcranial direct current stimulation, transcranial magnetic stimulation and neurofeedback have been employed and achieved promising outcomes. These interventions and treatments appear to normalize hyper- and hypoactivations of brain regions involved with reward processing, food-intake control, and cognitive function, and also promote recovery of brain structural abnormalities. This paper provides a comprehensive literature review of the recent neuroimaging advances on the underlying neural mechanisms of both obesity and interventions, in the hope of guiding development of novel and effective treatments.

Evaluating the neural substrates of effort-expenditure for reward in adults with major depressive disorder and obesity

Converging evidence has suggested that disturbances in monetary reward processing may subserve the shared biosignature between major depressive disorder (MDD) and obesity. However, there remains a paucity of studies that have evaluated the deficits in specific subcomponents of reward functioning in populations with MDD and obesity comorbidity. We evaluated the association between effort-expenditure for monetary reward and neural activation in regions associated with reward-based decision making (i.e., the caudate nucleus, anterior cingulate cortex (ACC) and hippocampus) in people with MDD and obesity comorbidity. We acquired structural and functional magnetic resonance imaging (fMRI) in 12 participants and performed a spherical region-of-interest analysis (ROI) using previously defined peak MNI coordinates. A one-sample t-test was employed to compare ROI-specific blood-oxygen-level-dependent (BOLD) signal change during the task choice selection window (i.e., high-effort vs. low-effort task) of the effort-expenditure for reward task (EEfRT). We observed no change in activation of the caudate nucleus, ACC or hippocampus in participants with increased BMI when contrasting the high effort > low effort reward magnitude condition for the EEfRT. The findings from our exploratory study evaluated the disturbances in fundamental reward processes, including cost-benefit decision making, in people MDD and obesity. Future studies should further investigate this relationship with a larger sample size.

Extended and replicated white matter changes in obesity: Voxel-based and region of interest meta-analyses of diffusion tensor imaging studies

Introduction

Obesity has become a global public health issue, which impacts general health and the brain. Associations between obesity and white matter microstructure measured using diffusion tensor imaging have been under reviewed, despite a relatively large number of individual studies. Our objective was to determine the association between obesity and white matter microstructure in a large general population sample.

Methods

We analyzed location of brain white matter changes in obesity using the Anisotropic Effect Size Seed-based d Mapping (AES-SDM) method in a voxel-based meta-analysis, with validation in a region of interest (ROI) effect size meta-analysis. Our sample included 21 742 individuals from 51 studies.

Results

The voxel-based spatial meta-analysis demonstrated reduced fractional anisotropy (FA) with obesity in the genu and splenium of the corpus callosum, middle cerebellar peduncles, anterior thalamic radiation, cortico-spinal projections, and cerebellum. The ROI effect size meta-analysis replicated associations between obesity and lower FA in the genu and splenium of the corpus callosum, middle cerebellar peduncles. Effect size of obesity related brain changes was small to medium.

Discussion

Our findings demonstrate obesity related brain white matter changes are localized rather than diffuse. Better understanding the brain correlates of obesity could help identify risk factors, and targets for prevention or treatment of brain changes.