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Obesity contributes to physical comorbidities and mental health consequences. We explored whether physical activity could influence more than metabolic regulation and result in psychological benefits through the brain-gut microbiome (BGM) system in a population with high BMI. Fecal samples were obtained for 16 s rRNA profiling and fecal metabolomics, along with psychological and physical activity questionnaires. Whole brain resting-state functional MRI was acquired, and brain connectivity metrics were calculated. Higher physical activity was significantly associated with increased connectivity in inhibitory appetite control brain regions, while lower physical activity was associated with increased emotional regulation network connections. Higher physical activity was also associated with microbiome and metabolite signatures protective towards mental health and metabolic derangements. The greater resilience and coping, and lower levels of food addiction seen with higher physical activity, may be explained by BGM system differences. These novel findings provide an emphasis on the psychological and resilience benefits of physical activity, beyond metabolic regulation and these influences seem to be related to BGM interactions. [ABSTRACT FROM AUTHOR]

Functional neuroimaging studies in obesity have identified alterations in the connectivity within the reward network leading to decreased homeostatic control of ingestive behavior. However, the neural mechanisms underlying sex differences in the prevalence of food addiction in obesity is unknown. The aim of the study was to identify functional connectivity alterations associated with: (1) Food addiction, (2) Sex- differences in food addiction, (3) Ingestive behaviors. 150 participants (females: N = 103, males: N = 47; food addiction: N = 40, no food addiction: N = 110) with high BMI ≥ 25 kg/m2 underwent functional resting state MRIs. Participants were administered the Yale Food Addiction Scale (YFAS), to determine diagnostic criteria for food addiction (YFAS Symptom Count ≥ 3 with clinically significant impairment or distress), and completed ingestive behavior questionnaires. Connectivity differences were analyzed using a general linear model in the CONN Toolbox and images were segmented using the Schaefer 400, Harvard–Oxford Subcortical, and Ascending Arousal Network atlases. Significant connectivities and clinical variables were correlated. Statistical significance was corrected for multiple comparisons at q <.05. (1) Individuals with food addiction had greater connectivity between brainstem regions and the orbital frontal gyrus compared to individuals with no food addiction. (2) Females with food addiction had greater connectivity in the salience and emotional regulation networks and lowered connectivity between the default mode network and central executive network compared to males with food addiction. (3) Increased connectivity between regions of the reward network was positively associated with scores on the General Food Cravings Questionnaire-Trait, indicative of greater food cravings in individuals with food addiction. Individuals with food addiction showed greater connectivity between regions of the reward network suggesting dysregulation of the dopaminergic pathway. Additionally, greater connectivity in the locus coeruleus could indicate that the maladaptive food behaviors displayed by individuals with food addiction serve as a coping mechanism in response to pathological anxiety and stress. Sex differences in functional connectivity suggest that females with food addiction engage more in emotional overeating and less cognitive control and homeostatic processing compared to males. These mechanistic pathways may have clinical implications for understanding the sex-dependent variability in response to diet interventions. [ABSTRACT FROM AUTHOR]

The brain-gut-microbiome (BGM) system plays an influential role on mental health. We characterized BGM patterns related to resilience using fecal samples and multimodal MRI. Data integration analysis using latent components showed the high resilience phenotype was associated with lower depression and anxiety symptoms, higher frequency of bacterial transcriptomes (related to environmental adaptation, genetic propagation, energy metabolism, anti-inflammation), increased metabolites (N-acetylglutamate; dimethylglycine), and cortical signatures (increased resting state functional connectivity between reward circuits and sensorimotor networks; decreased grey matter volume and white matter tracts within the emotion regulation network). Our findings support a multi-omic signature involving the BGM system suggesting that resilience impacts psychological symptoms, emotion regulation and cognitive function as reflected by unique neural correlates and microbiome function supporting eubiosis and gut barrier integrity. Bacterial transcriptomes provided the highest classification accuracy suggesting that the microbiome is critical in shaping resilience and highlights that microbiome modifications can optimize mental health., Competing Interests: Competing Interests Statement: AG is scientific advisor to Yamaha. All other authors have nothing to disclose.