Dietary and metabolic risk of neuropsychiatric disorders: insights from animal models

Depression and NAFLD risk: A meta-analysis and Mendelian randomization study

BACKGROUND

Both depression and nonalcoholic fatty liver disease (NAFLD) have a high global prevalence. Growing evidence suggests an association between depression and NAFLD, while the association remains unclear. Thus, in this study, we aimed to explore the effect of depression on the risk of developing NAFLD.

METHODS

The meta-analysis examined the association between depression and the risk of NAFLD by including observational studies. Relevant studies were searched in PubMed, Embase, the Cochrane Library, and Web of Science. Then a two-sample Mendelian randomization (MR) analysis was performed to explore causal association using genetic instruments identified from a genome-wide association study.

RESULTS

Six eligible studies were included in the meta-analysis, involving 289,22 depression cases among 167,554 participants. Meta-analysis showed a significant association between depression and a higher risk of developing NAFLD (OR = 1.14, 95 % CI: [1.05, 1.24], P = 0.002). However, we found no convincing evidence supporting a causal role of genetically predicted depression with NAFLD risk (OR = 0.861, 95 % CI: [0.598, 1.238], P = 0.420).

LIMITATIONS

The insufficient number of included studies, the use of summary-level data, and restrictions on population sources are the major limiting factors.

CONCLUSIONS

Meta-analysis and MR analysis demonstrated inconsistent results on the relationship between depression and a high risk of developing NAFLD. Specifically, meta-analysis confirmed that depression increases the risk of developing NAFLD, while MR analysis did not support a causal association between genetically determined depression and the risk of NAFLD.

Non-alcoholic fatty liver disease and coexisting depression, anxiety and/or stress in adults: a systematic review and meta-analysis

Background

Non-alcoholic fatty liver disease (NAFLD) is a common chronic liver disease, affecting 25-30% of the general population globally. The condition is even more prevalent in individuals with obesity and is frequently linked to the metabolic syndrome. Given the known associations between the metabolic syndrome and common mental health issues, it is likely that such a relationship also exists between NAFLD and mental health problems. However, studies in this field remain limited. Accordingly, the aim of this systematic review and meta-analysis was to explore the prevalence of one or more common mental health conditions (i.e., depression, anxiety, and/or stress) in adults with NAFLD.

Methods

PubMed, EBSCOhost, ProQuest, Ovid, Web of Science, and Scopus were searched in order to identify studies reporting the prevalence of depression, anxiety, and/or stress among adults with NAFLD. A random-effects model was utilized to calculate the pooled prevalence and confidence intervals for depression, anxiety and stress.

Results

In total, 31 studies were eligible for inclusion, involving 2,126,593 adults with NAFLD. Meta-analyses yielded a pooled prevalence of 26.3% (95% CI: 19.2 to 34) for depression, 37.2% (95% CI: 21.6 to 54.3%) for anxiety, and 51.4% (95% CI: 5.5 to 95.8%) for stress among adults with NAFLD.

Conclusion

The present findings suggest a high prevalence of mental health morbidity among adults with NAFLD. Given the related public health impact, this finding should prompt further research to investigate such associations and elucidate potential associations between NAFLD and mental health morbidity, exploring potential shared underlying pathophysiologic mechanisms.

Systematic review registration

https://www.crd.york.ac.uk/prospero/, identifier CRD42021288934.

Apple polyphenol extract ameliorates sugary-diet-induced depression-like behaviors in male C57BL/6 mice by inhibiting the inflammation of the gut-brain axis

To explore whether apple polyphenol extract (APE) ameliorates sugary-diet-induced depression-like behaviors, thirty male C57BL/6 mice (3-4 weeks old) were assigned to three groups randomly to receive different treatments for 8 consecutive weeks: (1) control group (CON), (2) S-HSD group (60% high sucrose diet feeding with 0.1 mg mL-1 sucralose solution as drinking water), and (3) S-APE group (S-HSD feeding with 500 mg per (kg bw day) APE solution gavage). The S-HSD group showed significant depression-like behaviors compared with the CON group, which was manifested by an increased number of buried marbles in the marble burying test, prolonged immobility time in both the tail suspension test and forced swimming test, and cognitive impairment based on the Morris water maze test. However, APE intervention significantly improved the depression-like behaviors by reducing serum levels of corticosterone and adrenocorticotropic hormone, and increasing the serum level of IL-10. Moreover, APE intervention inhibited the activation of the NF-κB inflammatory pathway, elevated colonic MUC-2 protein expression, and elevated the colonic and hippocampal tight junction proteins of occludin and ZO-1. Furthermore, APE intervention increased the richness and diversity of gut microbiota by regulating the composition of microbiota, with increased relative abundance of Firmicutes and Bacteroidota, decreased relative abundance of Verrucomicrobiota at the phylum level, significantly lowered relative abundance of Akkermansia at the genus level, and rebalanced abnormal relative abundance of Muribaculaceae_unclassified, Coriobacteriaceae_UCG-002, and Lachnoclostridium induced by S-HSD feeding. Thus, our study supports the potential application of APE as a dietary intervention for ameliorating depression-like behavioral disorders.

Association between cognitive capacity and metabolic indices in patients with neuropsychiatric disorders

BACKGROUND

Although previous studies suggested the relationship between metabolic indices and cognitive capacity, results have been conflicting. The prevalence of metabolic and cognitive disorders is high in patients with neuropsychiatric disorders. We aimed to assess the relationship between laboratory metabolic indices and specific areas of cognitive capacity.

MATERIALS AND METHODS

This was a retrospective review of the medical records of 423 from 452 patients with neuropsychiatric disorders who were admitted to the neuropsychiatry unit, Ayatollah Kashani Hospital, Isfahan, Iran, from September 1, 2018, to September 30, 2022. We extracted demographic factors, laboratory metabolic indices, and scores of the Neuropsychiatry Unit Cognitive Assessment tool (NUCOG). We utilized a generalized linear model (GLM) to demonstrate the effect of metabolic indices on the risk of reduction in cognitive domains. Due to the presence of missing data in the metabolic indices, we used the multiple imputation method.

RESULTS

The regression coefficient of NUCOG total score and subscale scores for metabolic indices using GLM after multiple imputation method demonstrated that among the metabolic indicators, fasting blood sugar (FBS) had the reverse relationship with the total score of NUCOG (β = -.05). Among the NUCOG subscales, executive functioning had the strongest relationship with FBS (β = -.01). Also, there was a negative relationship between patients' age and the total score of NUCOG (β = -.38). Educational level had a positive relationship with the total NUCOG score (β =10.2).

CONCLUSIONS

The main metabolic factors that might reduce cognitive capacity were higher FBS.

High-cholesterol diet promotes depression- and anxiety-like behaviors in mice by impact gut microbe and neuroinflammation

Neuropsychiatric disorders, including anxiety and depression, are one of the most common mental illnesses worldwide. A growing body of evidence shows that there is a complex relationship between dietary patterns and mental health. In our study, C57BL/6J mice were divided into three groups: control diet group (CON, 10 % kcal fat), high-cholesterol diet model group (HCD, 42.0 % kcal fat + 1.25 % kcal Cholesterol), and chronic restraint stress group (CRS, 10 % kcal fat) which as a positive control group for the depression model. Six weeks later, depressive- and anxiety-like behavior were evaluated for using the OFT, SPT and TST. Glucose intolerance and liver fat were detected by IGTT and liver lipid kit. The expression of peripheral and central inflammation was detected by LEGEND plex kits. 5-HT (also named 5-hydroxytryptamine, 5-HT) and related receptors expression were monitored by ELISA, RT-PCR and Western blot. Meantime, gut microbe of stool samples was performed by 16S rRNA gene sequencing. Similar to CRS model, short-term HCD intervention induced anxiety and depression-like behavior behavioral abnormalities in mice. HCD consumption resulted in significantly increased body weight, liver fat (LDL-C, TC, TG), peripheral inflammation (IL-1β, MCP-1, IL-17A) and neuroinflammation (MCP-1). The concentration of 5-HT increased in the hippocampus, meanwhile, the expression of 5-HT receptor HTR2A was distinct in different regions of the brain tissue. More importantly, we found that compared with the CON diet, HCD induced the decrease of intestinal flora diversity, especially the decrease the relative abundance of Akkermansia_muciniphila, which was statistically significant. Further, Pearson correlation analysis showed that Akkermansia_muciniphila was significantly negatively correlated with the concentration of MCP-1, IL-17A in serum and 5-HT in hippocampus. Therefore, we speculated that the disorder of neuroinflammation induced by HCD consumption promotes depression- and anxiety-like behaviors in mice through the gut microbe.

Anxiety and Metabolic Disorders: The Role of Botanicals

Anxiety and anxiety-related disorders are becoming more evident every day, affecting an increasing number of people around the world. Metabolic disorders are often associated with anxiety. Furthermore, anxiety branches into metabolic disorders by playing multiple roles as a cofactor, symptom, and comorbidity. Taken together, these considerations open the possibility of integrating the therapy of metabolic disorders with specific drugs for anxiety control. However, anxiolytic compounds often cause disabling effects in patients. The main goal could be to combine therapeutic protocols with compounds capable of reducing side effects while performing multiple beneficial effects. In this article we propose a group of bioactive ingredients called botanicals as a healthy supplement for the treatment of metabolic disorders related to anxiety.

Neurobiological Mechanisms Modulating Emotionality, Cognition and Reward-Related Behaviour in High-Fat Diet-Fed Rodents

Affective and substance-use disorders are associated with overweight and obesity-related complications, which are often due to the overconsumption of palatable food. Both high-fat diets (HFDs) and psychostimulant drugs modulate the neuro-circuitry regulating emotional processing and metabolic functions. However, it is not known how they interact at the behavioural level, and whether they lead to overlapping changes in neurobiological endpoints. In this literature review, we describe the impact of HFDs on emotionality, cognition, and reward-related behaviour in rodents. We also outline the effects of HFD on brain metabolism and plasticity involving mitochondria. Moreover, the possible overlap of the neurobiological mechanisms produced by HFDs and psychostimulants is discussed. Our in-depth analysis of published results revealed that HFDs have a clear impact on behaviour and underlying brain processes, which are largely dependent on the developmental period. However, apart from the studies investigating maternal exposure to HFDs, most of the published results involve only male rodents. Future research should also examine the biological impact of HFDs in female rodents. Further knowledge about the molecular mechanisms linking stress and obesity is a crucial requirement of translational research and using rodent models can significantly advance the important search for risk-related biomarkers and the development of clinical intervention strategies.

Non-Alcoholic Fatty Liver Disease (NAFLD) and Potential Links to Depression, Anxiety, and Chronic Stress

Non-alcoholic fatty liver disease (NAFLD) constitutes the most common liver disease worldwide, and is frequently linked to the metabolic syndrome. The latter represents a clustering of related cardio-metabolic components, which are often observed in patients with NAFLD and increase the risk of cardiovascular disease. Furthermore, growing evidence suggests a positive association between metabolic syndrome and certain mental health problems (e.g., depression, anxiety, and chronic stress). Given the strong overlap between metabolic syndrome and NAFLD, and the common underlying mechanisms that link the two conditions, it is probable that potentially bidirectional associations are also present between NAFLD and mental health comorbidity. The identification of such links is worthy of further investigation, as this can inform more targeted interventions for patients with NAFLD. Therefore, the present review discusses published evidence in relation to associations of depression, anxiety, stress, and impaired health-related quality of life with NAFLD and metabolic syndrome. Attention is also drawn to the complex nature of affective disorders and potential overlapping symptoms between such conditions and NAFLD, while a focus is also placed on the postulated mechanisms mediating associations between mental health and both NAFLD and metabolic syndrome. Relevant gaps/weaknesses of the available literature are also highlighted, together with future research directions that need to be further explored.