Cognitive Changes and Brain Volume Reduction in Patients with Nonalcoholic Fatty Liver Disease

Liver as a new target organ in Alzheimer's disease: insight from cholesterol metabolism and its role in amyloid-beta clearance

Alzheimer's disease, the primary cause of dementia, is characterized by neuropathologies, such as amyloid plaques, synaptic and neuronal degeneration, and neurofibrillary tangles. Although amyloid plaques are the primary characteristic of Alzheimer's disease in the central nervous system and peripheral organs, targeting amyloid-beta clearance in the central nervous system has shown limited clinical efficacy in Alzheimer's disease treatment. Metabolic abnormalities are commonly observed in patients with Alzheimer's disease. The liver is the primary peripheral organ involved in amyloid-beta metabolism, playing a crucial role in the pathophysiology of Alzheimer's disease. Notably, impaired cholesterol metabolism in the liver may exacerbate the development of Alzheimer's disease. In this review, we explore the underlying causes of Alzheimer's disease and elucidate the role of the liver in amyloid-beta clearance and cholesterol metabolism. Furthermore, we propose that restoring normal cholesterol metabolism in the liver could represent a promising therapeutic strategy for addressing Alzheimer's disease.

A narrative review about cognitive impairment in Metabolic Dysfunction-Associated Steatotic Liver Disease (MASLD): Another matter to face through a holistic approach

BACKGROUND

Metabolic dysfunction-associated steatotic liver disease (MASLD) is the most common chronic hepatic disorder worldwide in both adults and children. It is well established that MASLD represents the hepatic manifestation of the metabolic syndrome whose definition includes the presence of obesity, type 2 diabetes (T2D), dyslipidemia, hypertension and hypercoagulability. All these conditions contribute to a chronic inflammatory status which may impact on blood brain barrier (BBB) integrity leading to an impaired function of central nervous system (CNS).

AIM OF REVIEW

Since the mechanisms underlying the brain-liver-gut axis derangement are still inconclusive, the present narrative review aims to make a roundup of the most recent studies regarding the cognitive decline in MASLD also highlighting possible therapeutic strategies to reach a holistic advantage for the patients.

KEY SCIENTIFIC CONCEPTS OF REVIEW

Due to its ever-growing prevalence, the MASLD-related mental dysfunction represents an enormous socio-economic burden since it largely impacts on the quality of life of patients as well as on their working productivity. Indeed, cognitive decline in MASLD translates in low concentration and processing speed, reduced memory, sleepiness but also anxiety and depression. Chronic systemic inflammation, hyperammonemia, genetic background and intestinal dysbiosis possibly contribute to the cognitive decline in MASLD patients. However, its diagnosis is still underestimated since the leading mechanisms are multi-faceted and unexplained and do not exist standardized diagnostic tools or cognitive test strategies. In this scenario, nutritional and lifestyle interventions as well as intestinal microbiota manipulation (probiotics, fecal transplantation) may represent new approaches to counteract mental impairment in these subjects. In sum, to face the "mental aspect" of this multifactorial disease which is almost unexplored, cognitive tools should be introduced in the management of MASLD patients.

Non-alcoholic fatty liver disease is associated with structural covariance network reconfiguration in cognitively unimpaired adults with type 2 diabetes

Type 2 diabetes (T2D) is often accompanied by non-alcoholic fatty liver disease (NAFLD), both of which are related to brain damage and cognitive impairment. However, cortical structural alteration and its relationship with metabolism and cognition in T2D with NAFLD (T2NAFLD) and without NAFLD (T2noNAFLD) remain unclear. The brain MRI scans, clinical measures and neuropsychological test were evaluated in 50 normal controls (NC), 73 T2noNAFLD, and 58 T2NAFLD. The cortical thickness and graph theory properties of structural covariance network was calculated. Statistical analyses included one-way analysis of covariance with post hoc, partial correlation and mediation analysis. The nonparametric permutation test was performed to evaluate differences in topological properties of structural covariance network. We found T2NAFLD group had worse glucose and lipid profiles, more obesity and more severe insulin resistance, and poorer working memory compared to T2noNAFLD and NC. T2D patients demonstrated increase in cortical thickness compared to NC, but no difference between the two T2D groups. The structural covariance network integration decreased in T2D patients, with T2NAFLD exhibiting more obvious network reconfiguration at node level. Cortical thickness mediated the relationship between post-prandial glucose, waist-hip ratio, and working memory. The findings suggest that cortical thickening may be a compensatory response to reduced network integration, with NAFLD exacerbating regional structural network changes in T2D. This research advances our understanding of how these metabolic comorbidities contribute to cognitive decline, potentially guiding future therapeutic strategies for T2D patients with and without NAFLD.

Effects of Metabolic Dysfunction-Associated Steatohepatitis in Alertness, Associative Learning, and Astrocyte Density

PURPOSE

Metabolic dysfunction-associated steatohepatitis (MASH) is a prevalent disease caused by high fat and high cholesterol intake, which leads to systemic deterioration. The aim of this research is to conduct a psychobiological exploration of MASH in adult male rats.

METHODS

Subjects who were administered a high-fat and high-cholesterol diet for 14 weeks. Then, we assessed the acoustic startle response and alertness through the prepulse inhibition paradigm as well as the associative learning by the use of the passive avoidance test. Also, we explored the astrocyte density in the prefrontal cortex and hippocampus.

RESULTS

Our results showed that, whereas the MASH group did not display an impaired associative learning, a lower exploration rate was found in this group. Moreover, a reduced prepulse inhibition was found in these subjects in the case of the weaker and closer-to-the-stimulus prepulse, which indicates a mild alteration in this process. No differences were found in astrocyte density in the MASH group in comparison with controls.

CONCLUSION

MASH seems to be linked with cognitive dysfunction. Further research is needed to elucidate the pathway involved in this disease and its underlying mechanism, as well as the potential implication in human health.

A Mechanistic Review on Toxicity Effects of Methamphetamine

Persistent methamphetamine use causes many toxic effects in various organs, including the brain, heart, liver, kidney and eyes. The extent of its toxicity depends on numerous pharmacological factors, including route of administration, dose, genetic polymorphism related to drug metabolism and polysubstance abuse. Several molecular pathways have been proposed to activate oxidative stress, inflammation and apoptosis: B-cell lymphoma protein 2 (Bcl-2)-associated X (Bax)/Bcl2/caspase-3, nuclear factor erythroid 2-related factor (Nrf2)/heme oxygenase-1 (HO-1), protein kinase B (Akt)/mammalian target of rapamycin (mTOR)/p70S6K, trace amine-associated receptor 1 (TAAR1)/cAMP/lysyl oxidase, Sigmar1/ cAMP response element-binding protein (CREB)/mitochondrial fission-1 protein (Fis1), NADPH-Oxidase-2 (NOX-2), renal autophagy pathway, vascular endothelial growth factor (VEGF)/phosphatidylinositol-3-kinase (PI3K)/ protein kinase B (Akt)/endothelial nitric oxide synthase (eNOS), Nupr1/Chop/P53/PUMA/Beclin1 and Toll-like receptor (TLR)4/MyD88/TRAF6 pathways. The activation promotes pathological changes, including the disruption of the blood-brain barrier, myocardial infarction, cardiomyopathy, acute liver failure, acute kidney injury, chronic kidney disease, keratitis, retinopathy and vision loss. This review revisits the pharmacological profiles of methamphetamine and its effects on the brain, heart, liver, eyes, kidneys and endothelium. Understanding the mechanisms of methamphetamine toxicity is essential in developing treatment strategies to reverse or attenuate the progress of methamphetamine-associated organ damage.

The liver-brain axis in metabolic dysfunction-associated steatotic liver disease

Metabolic dysfunction-associated steatotic liver disease (MASLD) affects around 30% of the global population. Studies suggest that MASLD is associated with compromised brain health and cognitive dysfunction, initiating a growing interest in exploring the liver-brain axis mechanistically within MASLD pathophysiology. With the prevalence of MASLD increasing at an alarming rate, leaving a large proportion of people potentially at risk, cognitive dysfunction in MASLD is a health challenge that requires careful consideration and awareness. This Review summarises the current literature on cognitive function in people with MASLD and discusses plausible causes for its impairment. It is likely that a multifaceted spectrum of factors works collectively to affect cognition in patients with MASLD. We describe the role of inflammation, vascular disease, and brain ageing and neurodegeneration as possible key players. This Review also highlights the need for future studies to identify the optimal test for diagnosing cognitive dysfunction in patients with MASLD, to examine the correlation between MASLD progression and the severity of cognitive dysfunction, and to evaluate whether new MASLD-targeted therapies also improve brain dysfunction.

Cognitive Impairment in MASLD is associated with Amygdala-Related Connectivity Dysfunction in the Prefrontal and Sensory Cortex

BACKGROUND

Metabolic dysfunction-associated steatotic liver disease (MASLD) is a common metabolism-related multisystem clinical disorder, often accompanied by a high comorbidity of mild cognitive impairment (MCI). Increasing evidence suggests that the amygdala is crucial in cognitive processing during metabolic dysfunction. Nevertheless, the role of the amygdala in the neural mechanisms of MASLD with MCI (MCI_MASLD) remains unclear.

METHODS

A total of 74 MASLD patients (43 with MCI_MASLD and 31 without MCI [nonMCI_MASLD]) and 62 demographic-matched healthy controls (HC) were enrolled. All participants underwent resting-state functional magnetic resonance imaging scans and psychological scale assessments. Liver fat content and blood index measurements were performed on the patients. Using the bilateral amygdala as seeds, the seed-based functional connectivity (FC) maps were calculated and one-way analysis of covariance with post hoc tests was performed to investigate the difference among the three groups.

RESULTS

Compared to nonMCI_MASLD patients, MCI_MASLD patients demonstrated enhanced FC between the right amygdala and the medial prefrontal cortex (mPFC), while reduced FC between the left amygdala and the left supplementary motor area (SMA). Interestingly, the FC values of the mPFC were correlated with the Montreal Cognitive Assessment Scale (MoCA) scores and liver controlled attenuation parameters, and the FC values of the SMA were also correlated with the MoCA scores. Furthermore, the FC values between the bilateral amygdala and regions within the frontal-limbic-mesencephalic circuits were higher in MASLD patients when compared to HC.

CONCLUSIONS

Aberrant FC of the amygdala can provide potential neuroimaging markers for MCI in MASLD, which is associated with amygdala-related connectivity disturbances in areas related to cognition and sensory processing. Moreover, visceral fat accumulation may exacerbate brain dysfunction.

Comparative analysis of NAFLD-related health videos on TikTok: a cross-language study in the USA and China

BACKGROUND

The incidence of Non-alcoholic fatty liver disease (NAFLD) in China and USA is extremely high and rising. TikTok has become a popular channel for medical information dissemination and we aimed to evaluate the quality and reliability of NAFLD related videos on TikTok, in both its USA and Chinese versions.

METHODS

We analyzed the top 100 NAFLD videos on both the USA version and Chinese version of TikTok, a total of 200 videos, from which keywords were extracted and scored using the Global Quality Scale (GQS), modified DISCERN (mDISCERN), and Medical Quality Video Evaluation Tool (MQ-VET). Exploring the relationship between video quality and audience related factors, as well as ranking, through Spearman correlation analysis.

RESULTS

The mDISCERN scores of videos on the USA version of TikTok is higher than that on the Chinese version (P < 0.01), but there is no significant difference in the GQS and MQ-VET scores. The GQS, mDISCERN and MQ-VET scores of videos published by medical practitioners were significantly higher than those of non-medical practitioners (P < 0.001). However, there was no significant correlation between video quality and popularity indicators.

CONCLUSION

The quality of NAFLD related short videos on TikTok is acceptable, but the reliability is mediocre, and there is still room for improvement. The videos published by USA medical practitioners are more reliable than those of Chinese medical practitioners. The most concerned topic of both countries is diet. The TikTok recommendation algorithm may limit access to high-quality health videos, and further research on other platforms and languages is necessary.

Multisystem health comorbidity networks of metabolic dysfunction-associated steatotic liver disease

BACKGROUND

The global burden of metabolic dysfunction-associated steatotic liver disease (MASLD) is growing, but its subsequent health consequences have not been thoroughly examined.

METHODS

A phenome-wide association study was conducted to map the associations of MASLD with 948 unique clinical outcomes among 361,021 Europeans in the UK Biobank. Disease trajectory and comorbidity analyses were applied to visualize the sequential patterns of multiple comorbidities related to the occurrence of MASLD. The associations jointly verified by observational and polygenic phenome-wide analyses were further replicated by two-sample Mendelian randomization analysis using data from the FinnGen study and international consortia.

FINDINGS

The observational and polygenic phenome-wide association study revealed the associations of MASLD with 96 intrahepatic and extrahepatic diseases, including circulatory, metabolic, genitourinary, neurological, gastrointestinal, and hematologic diseases. Sequential patterns of MASLD-related extrahepatic comorbidities were primarily found in circulatory, metabolic, and inflammatory diseases. Mendelian randomization analyses supported the causal associations between MASLD and the risk of several intrahepatic disorders, metabolic diseases, cardio-cerebrovascular disease, and ascites but found no associations with neurological diseases.

CONCLUSIONS

This study elucidated multisystem comorbidities and health consequences of MASLD, contributing to the development of combination interventions targeting distinct pathways for health promotion among patients with MASLD.

FUNDING

X.L. was funded by the Natural Science Fund for Distinguished Young Scholars of Zhejiang Province (LR22H260001) and the National Nature Science Foundation of China (82204019) and Y.D. was funded by the Key Project of Traditional Chinese Medicine Science and Technology Plan of Zhejiang Province (GZY-ZJ-KJ-24077) and the National Natural Science Foundation of China (82001673 and 82272860).

Ovariectomy and High Fat-Sugar-Salt Diet Induced Alzheimer's Disease/Vascular Dementia Features in Mice

While the vast majority of Alzheimer's disease (AD) is non-familial, the animal models of AD that are commonly used for studying disease pathogenesis and development of therapy are mostly of a familial form. We aimed to generate a model reminiscent of the etiologies related to the common late-onset Alzheimer's disease (LOAD) sporadic disease that will recapitulate AD/dementia features. Naïve female mice underwent ovariectomy (OVX) to accelerate aging/menopause and were fed a high fat-sugar-salt diet to expose them to factors associated with increased risk of development of dementia/AD. The OVX mice fed a high fat-sugar-salt diet responded by dysregulation of glucose/insulin, lipid, and liver function homeostasis and increased body weight with slightly increased blood pressure. These mice developed AD-brain pathology (amyloid and tangle pathologies), gliosis (increased burden of astrocytes and activated microglia), impaied blood vessel density and neoangiogenesis, with cognitive impairment. Thus, OVX mice fed on a high fat-sugar-salt diet imitate a non-familial sporadic/environmental form of AD/dementia with vascular damage. This model is reminiscent of the etiologies related to the LOAD sporadic disease that represents a high portion of AD patients, with an added value of presenting concomitantly AD and vascular pathology, which is a common condition in dementia. Our model can, thereby, provide a valuable tool for studying disease pathogenesis and for the development of therapeutic approaches.

Gossypetin targets the liver-brain axis to alleviate pre-existing liver fibrosis and hippocampal neuroinflammation in mice

Liver fibrosis occurs in response to chronic damage and inflammation to the liver. Leaving untreated, it can lead to decreased liver function and can eventually progress to cirrhosis, a more advanced and irreversible state of liver damage. Clinical investigations showed that chronic liver disease associated with neurological symptoms including anxiety, depression, and cognitive decline. However, few therapeutic options are available for treating liver and related brain pathologies simultaneously. In this study, we aim to find therapeutic candidates that target the liver-brain axis. Gossypetin, a flavonoid from sedum, shows promising capability in treating liver and brain pathologies in CCl4-induced mouse model. Short term of gossypetin administration is sufficient to ameliorate impaired liver function and pre-existing liver fibrosis, suppress MKK3/6-p38 MAPK and p53 activation, and abolish the activation of hepatic stellate cells and Kupffer cells. Although we observe no neuronal loss in the brain of mice with liver fibrosis, we do observe astrogliosis and microglial activation in certain brain regions, especially the hippocampus. Brief gossypetin administration also shows potential in alleviating neuroinflammation in these regions. These results suggest that gossypetin can target the liver-brain axis and be a promising candidate for treating chronic liver fibrosis patients with neurological symptoms.

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.

The Metabolic Impact of Nonalcoholic Fatty Liver Disease on Cognitive Dysfunction: A Comprehensive Clinical and Pathophysiological Review

Nonalcoholic fatty liver disease (NAFLD) exponentially affects the global healthcare burden, and it is currently gaining increasing interest in relation to its potential impact on central nervous system (CNS) diseases, especially concerning cognitive deterioration and dementias. Overall, scientific research nowadays extends to different levels, exploring NAFLD's putative proinflammatory mechanism of such dysmetabolic conditions, spreading out from the liver to a multisystemic involvement. The aim of this review is to analyze the most recent scientific literature on cognitive involvement in NAFLD, as well as understand its underlying potential background processes, i.e., neuroinflammation, the role of microbiota in the brain-liver-gut axis, hyperammonemia neurotoxicity, insulin resistance, free fatty acids, and vitamins.

Liver integrity and the risk of Alzheimer's disease and related dementias

INTRODUCTION

We examined midlife (1990-1992, mean age 57) and late-life (2011-2013, mean age 75) nonalcoholic fatty liver disease (NAFLD) and aminotransferase with incident dementia risk through 2019 in the Atherosclerosis Risk in Communities (ARIC) Study.

METHODS

We characterized NAFLD using the fatty liver index and fibrosis-4, and we categorized aminotransferase using the optimal equal-hazard ratio (HR) approach. We estimated HRs for incident dementia ascertained from multiple data sources.

RESULTS

Adjusted for demographics, alcohol consumption, and kidney function, individuals with low, intermediate, and high liver fibrosis in midlife (HRs: 1.45, 1.40, and 2.25, respectively), but not at older age, had higher dementia risks than individuals without fatty liver. A U-shaped association was observed for alanine aminotransferase with dementia risk, which was more pronounced in late-life assessment.

DISCUSSION

Our findings highlight dementia burden in high-prevalent NAFLD and the important feature of late-life aminotransaminase as a surrogate biomarker linking liver hypometabolism to dementia. Highlights Although evidence of liver involvement in dementia development has been documented in animal studies, the evidence in humans is limited. Midlife NAFLD raised dementia risk proportionate to severity. Late-life NAFLD was not associated with a high risk of dementia. Low alanine aminotransferase was associated with an elevated dementia risk, especially when measured in late life.

Crosstalk Between the Nervous System and Systemic Organs in Acute Brain Injury

Organ crosstalk is a complex biological communication between distal organs mediated via cellular, soluble, and neurohormonal actions, based on a two-way pathway. The communication between the central nervous system and peripheral organs involves nerves, endocrine, and immunity systems as well as the emotional and cognitive centers of the brain. Particularly, acute brain injury is complicated by neuroinflammation and neurodegeneration causing multiorgan inflammation, microbial dysbiosis, gastrointestinal dysfunction and dysmotility, liver dysfunction, acute kidney injury, and cardiac dysfunction. Organ crosstalk has become increasingly popular, although the information is still limited. The present narrative review provides an update on the crosstalk between the nervous system and systemic organs after acute brain injury. Future research might help to target this pathophysiological process, preventing the progression toward multiorgan dysfunction in critically ill patients with brain injury.

Association of Metabolic Dysfunction-Associated Fatty Liver Disease with Cognitive Impairment and All-Cause Dementia: A Comprehensive Review

Metabolic dysfunction-associated fatty liver disease (MAFLD) is a significant public health concern, affecting one-third of the global population and posing a risk for progressive liver disease. MAFLD is characterized by hepatic steatosis and impaired metabolic status, which not only impact the liver but also other systems of the human body, making it a multisystemic disorder. Emerging evidence suggests that MAFLD and its associated pathological pathways may contribute to cognitive impairment, potentially through neuroinflammation and neurodegeneration. Studies have detected cognitive impairment in patients with MAFLD using magnetic resonance imaging, which revealed decreased brain volume and cerebral perfusion, in addition to self-reported cognitive tests. While numerous studies have demonstrated an association between MAFLD and cognitive impairment, the relationship between MAFLD and all-cause dementia remains controversial. However, the shared pathological pathways between MAFLD and dementia, such as systemic inflammation, insulin resistance, gut dysbiosis, hyperammonemia, and vascular dysfunction, indicate the possibility of a common prevention strategy for both diseases. In this review, we provide a summary of the current evidence regarding the association between cognitive impairment, all-cause dementia, and MAFLD.

Non-alcoholic fatty liver disease causally affects the brain cortical structure: a Mendelian randomization study

Background

Reduced brain volume, impaired cognition, and possibly a range of psychoneurological disorders have been reported in patients with non-alcoholic fatty liver disease (NAFLD); however, no underlying cause has been specified. Here, Mendelian randomization (MR) was employed to determine the causative NAFLD effects on cortical structure.

Methods

We used pooled-level data from FinnGen's published genome-wide association study (GWAS) of NAFLD (1908 cases and 340,591 healthy controls), as well as published GWAS with NAFLD activity score (NAS) and fibrosis stage-associated SNPs as genetic tools, in addition to the Enigma Consortium data from 51,665 patients, were used to assess genetic susceptibility in relation to changes with cortical thickness (TH) and surface area (SA). A main estimate was made by means of inverse variance weighted (IVW), while heterogeneity and pleiotropy were detected using MR-Egger, weighted median, and MR Pleiotropy RESidual Sum and Outlier to perform a two-sample MR analysis.

Results

At the global level, NAFLD reduced SA (beta = -586.72 mm2, se = 217.73, p = 0.007) and several changes in the cortical structure of the cerebral gyrus were found, with no detectable pleiotropy.

Conclusion

NAFLD causally affects cortical structures, which supports the presence of an intricate liver-brain axis.

Ameliorative Role of Mitochondrial Therapy in Cognitive Function of Vascular Dementia Mice

BACKGROUND

Mitochondrial dysfunction plays a vital role in the progression of vascular dementia (VaD). We hypothesized that transfer of exogenous mitochondria might be a beneficial strategy for VaD treatment.

OBJECTIVE

The study was aimed to investigate the role of mitochondrial therapy in cognitive function of VaD.

METHODS

The activity and integrity of isolated mitochondria were detected using MitoTracker and Janus Green B staining assays. After VaD mice were intravenously injected with exogenous mitochondria, Morris water maze and passive avoidance tests were used to detect cognitive function of VaD mice. Haematoxylin and eosin, Nissl, TUNEL, and Golgi staining assays were utilized to measure neuronal and synaptic injury in the hippocampus of VaD mice. Detection kits were performed to detect mitochondrial membrane potential (ΔΨ), SOD activity and the levels of ATP, ROS, and MDA in the brains of VaD mice.

RESULTS

The results showed that isolated mitochondria were intact and active. Mitochondrial therapy could ameliorate cognitive performance of VaD mice. Additionally, mitochondrial administration could attenuate hippocampal neuronal and synaptic injury, improve mitochondrial ΔΨ, ATP level and SOD activity, and reduce ROS and MDA levels in the brains of VaD mice.

CONCLUSIONS

The study reports profitable effect of mitochondrial therapy against cognitive impairment of VaD, making mitochondrial treatment become a promising therapeutic strategy for VaD.

The Presence and Severity of NAFLD are Associated With Cognitive Impairment and Hippocampal Damage

CONTEXT

Although cognitive impairment in nonalcoholic fatty liver disease (NAFLD) has received attention in recent years, little is known about detailed cognitive functions in histologically diagnosed individuals.

OBJECTIVE

This study aimed to investigate the association of liver pathological changes with cognitive features and further explore the underlying brain manifestations.

METHODS AND PATIENTS

We performed a cross-sectional study in 320 subjects who underwent liver biopsy. Among the enrolled participants, 225 underwent assessments of global cognition and cognitive subdomains. Furthermore, 70 individuals received functional magnetic resonance imaging scans for neuroimaging evaluations. The associations among liver histological features, brain alterations, and cognitive functions were evaluated using structural equation model.

RESULTS

Compared with controls, patients with NAFLD had poorer immediate memory and delayed memory. Severe liver steatosis (odds ratio, 2.189; 95% CI, 1.020-4.699) and ballooning (OR, 3.655; 95% CI, 1.419-9.414) were related to a higher proportion of memory impairment. Structural magnetic resonance imaging showed that patients with nonalcoholic steatohepatitis exhibited volume loss in left hippocampus and its subregions of subiculum and presubiculum. Task-based magnetic resonance imaging showed that patients with nonalcoholic steatohepatitis had decreased left hippocampal activation. Path analysis demonstrated that higher NAFLD activity scores were associated with lower subiculum volume and reduced hippocampal activation, and such hippocampal damage contributed to lower delayed memory scores.

CONCLUSIONS

We are the first to report the presence and severity of NAFLD to be associated with an increased risk of memory impairment and hippocampal structural and functional abnormalities. These findings stress the significance of early cognitive evaluation in patients with NAFLD.

The bidirectional association of nonalcoholic fatty liver disease with depression, bipolar disorder, and schizophrenia

Nonalcoholic fatty liver disease (NAFLD) is a complex metabolic-inflammatory disease associated with poor outcomes and decreased quality of life. NAFLD is overrepresented in patients with psychiatric disorders like depression, bipolar disorder, and schizophrenia; however, a comprehensive review on NAFLD and psychiatric disorders remains to be delineated. This review endeavors to investigate the association of NAFLD with psychiatric disorders, including shared pathogenesis and future clinical derivatives. Extant literature suggests that patients with psychiatric disorders (in particular, mood disorders) are more susceptible to the development of NAFLD due to multiple reasons, including but not limited to hypothalamic-pituitary-adrenal axis dysregulation, metabolic syndrome, and chronic perceived stress. Moreover, the clinical manifestations of mood disorders (e.g., anhedonia, psychomotor retardation, lifestyle modification, etc.), and potentially long-term treatment with weight-gaining agents, differentially affect these patients, making them more prone to NAFLD. Considering the increased morbidity associated with both mood disorders and NAFLD, our review recommends regular screenings for NAFLD in select patients with mood disorders exhibiting signs of increased risk (i.e., obesity, metabolic syndrome, diabetes, or family history of NAFLD) for better diagnosis and holistic care of both potentially interrelated conditions.

Disruption of brain regional homogeneity and functional connectivity in male NAFLD: evidence from a pilot resting-state fMRI study

BACKGROUND

The neurophysiological mechanisms underlying cognitive deficits in non-alcoholic fatty liver disease (NAFLD) remain unknown. Cognitive changes may be caused by brain alterations in neural activity and functional connectivity (FC).

AIM

This study aims to investigate the alterations between spontaneous brain neural activity and FC in male NAFLD patients and the relationship of neural activity with cognitive performance.

METHODS

In this prospective study, 33 male pre-cirrhosis NAFLD subjects and 20 male controls matched for age, education level, and body mass index. All participants underwent resting-state functional magnetic resonance imaging scans and neuropsychological examinations. Regional homogeneity (ReHo) analysis was used to investigate the brain function in NAFLD, and regions with significantly altered ReHo were selected as seeds for subsequent FC analysis. Partial correlation analysis was used to assess the relationships between altered ReHo measures and cognitive performance indicators.

RESULTS

Compared with the controls, the NAFLD patients showed increased ReHo in the opercular part of the right inferior frontal gyrus (IFGoperc) and decreased ReHo in the right middle frontal gyrus (MFG) and left superior parietal gyrus (SPG). The subsequent FC analysis showed increased FC between these regions (right IFGoperc, right MFG, and left SPG) and nodes of the default mode network (DMN) (such as left supraMarginal, left median cingulate and paracingulate gyri, left precuneus, orbital part of left medial frontal gyrus, and bilateral posterior cingulate gyrus). In addition, significant positive correlations were observed between NAFLD patients' clock drawing test scores and altered ReHo in prefrontal cortices (right IFGoperc and right MFG).

CONCLUSION

Before developing cirrhosis, NAFLD patients showed altered neural activity in several brain regions and altered FC between the salience network and DMN. These alterations could potentially be a compensatory mechanism to maintain cognitive function in pre-cirrhosis NAFLD patients.

Impact of ectopic fat on brain structure and cognitive function:A systematic review and meta-analysis from observational studies

Ectopic fat, defined as a specific organ or compartment with the accumulation of fat tissue surrounding organs, is highly associated with obesity which has been identified as a risk factor for cognitive impairment and dementia. However, the relationship between ectopic fat and changes in brain structure or cognition is yet to be elucidated. Here, we investigated the effects of ectopic fat on brain structure and cognitive function via systemic review and meta-analysis. A total of 22 studies were included, encompassing 1,003,593 participants-obtained from electronic databases up to July 9, 2022. We found ectopic that fat was associated with decreased total brain volume and increased lateral ventricle volume. In addition, ectopic was associated with decreased cognitive scores and negatively correlated with cognitive function. More specifically, dementia development was correlated with increased levels of visceral fat. Overall, our data suggest that increased ectopic fat is associated with prominent structural changes in the brain and cognitive decline, an effect driven mainly by increases in visceral fat, while subcutaneous fat may be protective. Our results suggest that patients with increased visceral fat are at risk of developing cognitive impairment and, therefore, represent a subset of population in whom appropriate and timely preventive measures could be implemented.

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.

Regulation of mild cognitive impairment associated with liver disease by humoral factors derived from the gastrointestinal tract and MRI research progress: a literature review

Patients with liver disease are prone to various cognitive impairments. It is undeniable that cognitive impairment is often regulated by both the nervous system and the immune system. In this review our research focused on the regulation of mild cognitive impairment associated with liver disease by humoral factors derived from the gastrointestinal tract, and revealed that its mechanisms may be involved with hyperammonemia, neuroinflammation, brain energy and neurotransmitter metabolic disorders, and liver-derived factors. In addition, we share the emerging research progress in magnetic resonance imaging techniques of the brain during mild cognitive impairment associated with liver disease, in order to provide ideas for the prevention and treatment of mild cognitive impairment in liver disease.

Matrix disequilibrium in Alzheimer's disease and conditions that increase Alzheimer's disease risk

Alzheimer's Disease (AD) and related dementias are a leading cause of death globally and are predicted to increase in prevalence. Despite this expected increase in the prevalence of AD, we have yet to elucidate the causality of the neurodegeneration observed in AD and we lack effective therapeutics to combat the progressive neuronal loss. Throughout the past 30 years, several non-mutually exclusive hypotheses have arisen to explain the causative pathologies in AD: amyloid cascade, hyper-phosphorylated tau accumulation, cholinergic loss, chronic neuroinflammation, oxidative stress, and mitochondrial and cerebrovascular dysfunction. Published studies in this field have also focused on changes in neuronal extracellular matrix (ECM), which is critical to synaptic formation, function, and stability. Two of the greatest non-modifiable risk factors for development of AD (aside from autosomal dominant familial AD gene mutations) are aging and APOE status, and two of the greatest modifiable risk factors for AD and related dementias are untreated major depressive disorder (MDD) and obesity. Indeed, the risk of developing AD doubles for every 5 years after ≥ 65, and the APOE4 allele increases AD risk with the greatest risk in homozygous APOE4 carriers. In this review, we will describe mechanisms by which excess ECM accumulation may contribute to AD pathology and discuss pathological ECM alterations that occur in AD as well as conditions that increase the AD risk. We will discuss the relationship of AD risk factors to chronic central nervous system and peripheral inflammation and detail ECM changes that may follow. In addition, we will discuss recent data our lab has obtained on ECM components and effectors in APOE4/4 and APOE3/3 expressing murine brain lysates, as well as human cerebrospinal fluid (CSF) samples from APOE3 and APOE4 expressing AD individuals. We will describe the principal molecules that function in ECM turnover as well as abnormalities in these molecular systems that have been observed in AD. Finally, we will communicate therapeutic interventions that have the potential to modulate ECM deposition and turnover in vivo.

Physiological β-amyloid clearance by the liver and its therapeutic potential for Alzheimer's disease

Cerebral amyloid-β (Aβ) accumulation due to impaired Aβ clearance is a pivotal event in the pathogenesis of Alzheimer's disease (AD). Considerable brain-derived Aβ is cleared via transporting to the periphery. The liver is the largest organ responsible for the clearance of metabolites in the periphery. Whether the liver physiologically clears circulating Aβ and its therapeutic potential for AD remains unclear. Here, we found that about 13.9% of Aβ42 and 8.9% of Aβ40 were removed from the blood when flowing through the liver, and this capacity was decreased with Aβ receptor LRP-1 expression down-regulated in hepatocytes in the aged animals. Partial blockage of hepatic blood flow increased Aβ levels in both blood and brain interstitial fluid. The chronic decline in hepatic Aβ clearance via LRP-1 knockdown specific in hepatocytes aggravated cerebral Aβ burden and cognitive deficits, while enhancing hepatic Aβ clearance via LRP-1 overexpression attenuated cerebral Aβ deposition and cognitive impairments in APP/PS1 mice. Our findings demonstrate that the liver physiologically clears blood Aβ and regulates brain Aβ levels, suggesting that a decline of hepatic Aβ clearance during aging could be involved in AD development, and hepatic Aβ clearance is a novel therapeutic approach for AD.

Partial MCT1 invalidation protects against diet-induced non-alcoholic fatty liver disease and the associated brain dysfunction

BACKGROUND & AIMS

Non-alcoholic fatty liver disease (NAFLD) has been associated with mild cerebral dysfunction and cognitive decline, although the exact pathophysiological mechanism remains ambiguous. Using a diet-induced model of NAFLD and monocarboxylate transporter-1 (Mct1^+/-) haploinsufficient mice, which resist high-fat diet-induced hepatic steatosis, we investigated the hypothesis that NAFLD leads to an encephalopathy by altering cognition, behaviour, and cerebral physiology. We also proposed that global MCT1 downregulation offers cerebral protection.

METHODS

Behavioural tests were performed in mice following 16 weeks of control diet (normal chow) or high-fat diet with high fructose/glucose in water. Tissue oxygenation, cerebrovascular reactivity, and cerebral blood volume were monitored under anaesthesia by multispectral optoacoustic tomography and optical fluorescence. Cortical mitochondrial oxygen consumption and respiratory capacities were measured using ex vivo high-resolution respirometry. Microglial and astrocytic changes were evaluated by immunofluorescence and 3D reconstructions. Body composition was assessed using EchoMRI, and liver steatosis was confirmed by histology.

RESULTS

NAFLD concomitant with obesity is associated with anxiety- and depression-related behaviour. Low-grade brain tissue hypoxia was observed, likely attributed to the low-grade brain inflammation and decreased cerebral blood volume. It is also accompanied by microglial and astrocytic morphological and metabolic alterations (higher oxygen consumption), suggesting the early stages of an obesogenic diet-induced encephalopathy. Mct1 haploinsufficient mice, despite fat accumulation in adipose tissue, were protected from NAFLD and associated cerebral alterations.

CONCLUSIONS

This study provides evidence of compromised brain health in obesity and NAFLD, emphasising the importance of the liver-brain axis. The protective effect of Mct1 haploinsufficiency points to this protein as a novel therapeutic target for preventing and/or treating NAFLD and the associated brain dysfunction.

IMPACT AND IMPLICATIONS

This study is focused on unravelling the pathophysiological mechanism by which cerebral dysfunction and cognitive decline occurs during NAFLD and exploring the potential of monocarboxylate transporter-1 (MCT1) as a novel preventive or therapeutic target. Our findings point to NAFLD as a serious health risk and its adverse impact on the brain as a potential global health system and economic burden. These results highlight the utility of Mct1 transgenic mice as a model for NAFLD and associated brain dysfunction and call for systematic screening by physicians for early signs of psychological symptoms, and an awareness by individuals at risk of these potential neurological effects. This study is expected to bring attention to the need for early diagnosis and treatment of NAFLD, while having a direct impact on policies worldwide regarding the health risk associated with NAFLD, and its prevention and treatment.

Serum biomarkers of liver fibrosis identify globus pallidus vulnerability

The CNS manifestation of chronic liver disease can include magnetic resonance (MR) signal hyperintensities in basal ganglia structures. Here, relations between liver (serum-derived fibrosis scores) and brain (regional T1-weighted signal intensities and volumes) integrity were evaluated in a sample of 457 individuals including those with alcohol use disorders (AUD), people living with human immunodeficiency virus (HIV), those comorbid for AUD and HIV, and healthy controls. Liver fibrosis was identified from cutoff scores as follows: aspartate aminotransferase to platelet ratio index (APRI) > 0.7 in 9.4% (n = 43) of the cohort; fibrosis score (FIB4) > 1.5 in 28.0% (n = 128) of the cohort; and non-alcoholic fatty liver disease fibrosis score (NFS) > -1.4 in 30.2% (n = 138) of the cohort. Presence of serum-derived liver fibrosis was associated with high signal intensities selective to basal ganglia (i.e., caudate, putamen, and pallidum) structures. High signal intensities in the pallidum, however, explained a significant portion of the variance in APRI (25.0%) and FIB4 (23.6%) cutoff scores. Further, among the regions evaluated, only the globus pallidus showed a correlation between greater signal intensity and smaller volume (r = -0.44, p <.0001). Finally, higher pallidal signal intensity correlated worse ataxia (eyes open ρ = -0.23, p =.0002; eyes closed ρ = -0.21, p =.0005). This study suggests that clinically relevant serum biomarkers of liver fibrosis such as the APRI may identify individuals vulnerable to globus pallidus pathology and contribute to problems with postural balance.

Linking Nonalcoholic Fatty Liver Disease and Brain Disease: Focusing on Bile Acid Signaling

A metabolic illness known as non-alcoholic fatty liver disease (NAFLD), affects more than one-quarter of the world's population. Bile acids (BAs), as detergents involved in lipid digestion, show an abnormal metabolism in patients with NAFLD. However, BAs can affect other organs as well, such as the brain, where it has a neuroprotective effect. According to a series of studies, brain disorders may be extrahepatic manifestations of NAFLD, such as depression, changes to the cerebrovascular system, and worsening cognitive ability. Consequently, we propose that NAFLD affects the development of brain disease, through the bile acid signaling pathway. Through direct or indirect channels, BAs can send messages to the brain. Some BAs may operate directly on the central Farnesoid X receptor (FXR) and the G protein bile acid-activated receptor 1 (GPBAR1) by overcoming the blood-brain barrier (BBB). Furthermore, glucagon-like peptide-1 (GLP-1) and the fibroblast growth factor (FGF) 19 are released from the intestine FXR and GPBAR1 receptors, upon activation, both of which send signals to the brain. Inflammatory, systemic metabolic disorders in the liver and brain are regulated by the bile acid-activated receptors FXR and GPBAR1, which are potential therapeutic targets. From a bile acid viewpoint, we examine the bile acid signaling changes in NAFLD and brain disease. We also recommend the development of dual GPBAR1/FXR ligands to reduce side effects and manage NAFLD and brain disease efficiently.

Risk of dementia or cognitive impairment in non-alcoholic fatty liver disease: A systematic review and meta-analysis

Objectives

To investigate whether non-alcoholic fatty liver disease (NAFLD) increases the risk of dementia or cognitive impairment.

Methods

A systematic search of the literature in the PubMed, Excerpta Medica Database (EMBASE), Cochrane Library, and Web of Science databases was conducted, covering the period from the inception of each database to 22 May 2022. Statistical analysis of non-alcoholic fatty liver disease and the risk of cognitive impairment or dementia based on data extracted from each article was performed using Stata software v. 16.0. The quality of this study was assessed using the Newcastle-Ottawa Scale (NOS) for assessing the quality of cohort and case-control studies and the American Agency for Healthcare Research and Quality (AHRQ) methodology checklist for assessing the quality of cross-sectional studies. Funnel plots and the Egger's test were used to assess publication bias.

Results

We included 7 studies comprising 891,562 individuals from 6 countries, which were published between 2020 and 2022. The pooling analysis showed that a history of NAFLD was associated with cognitive impairment [odds ratio (OR) = 1.44; 95% CI: 1.17-1.78; heterogeneity (I 2) = 0%; P = 0.001]. A history of NAFLD was not associated with an increased risk of all-cause dementia (OR = 1.03; 95% CI: 0.97-1.09; I 2 = 84.7%; P = 0.341) or Alzheimer disease (OR = 0.95; 95% CI: 0.83-1.09; I 2 = 61.0%; P = 0.489). In contrast, NAFLD was associated with an obvious reduction of the risk of vascular dementia (OR = 0.88; 95% CI: 0.79-0.98; I 2 = 0.0%; P = 0.020). In the subgroup analysis, male and female patients with NAFLD showed an equal risk of dementia or cognitive impairment. The risk of dementia or cognitive impairment in the cross-sectional study (OR = 1.49; 95% CI: 1.19-1.88; I 2 = 0.0%; P = 0.001) was slightly higher than that in the retrospective cohort (OR = 1.03; 95% CI: 0.97-1.09; I 2 = 84.3%; P = 0.294).

Conclusions

NAFLD was associated with an increased risk of cognitive impairment and a decreased risk of vascular dementia. More studies are needed to clarify the pathophysiological mechanism underlying the association between NAFLD and dementia or cognitive impairment.

Systematic review registration

https://www.crd.york.ac.uk/prospero/#recordDetails, identifier: CRD42022334492.

The gut–microbiota–brain changes across the liver disease spectrum

Gut microbiota dysbiosis plays a significant role in the progression of liver disease, and no effective drugs are available for the full spectrum. In this study, we aimed to explore the dynamic changes of gut microbiota along the liver disease spectrum, together with the changes in cognition and brain metabolism. Sprague–Dawley rats were divided into four groups reflecting different stages of liver disease: control diet (NC); high-fat, high-cholesterol diet (HFHC), emulating non-alcoholic steatohepatitis; control diet + thioacetamide (NC + TAA), simulating acute liver failure; and high-fat, high-cholesterol diet + thioacetamide (HFHC + TAA) to assess the effect of the superimposed damages. The diet was administered for 14 weeks and the thioacetamide was administrated (100 mg/kg day) intraperitoneally over 3 days. Our results showed changes in plasma biochemistry and liver damage across the spectrum. Differences in gut microbiota at the compositional level were found among the experimental groups. Members of the Enterobacteriaceae family were most abundant in HFHC and HFHC + TAA groups, and Akkermansiaceae in the NC + TAA group, albeit lactobacilli genus being dominant in the NC group. Moreover, harm to the liver affected the diversity and bacterial community structure, with a loss of rare species. Indeed, the superimposed damage group (HFHC + TAA) suffered a loss of both rare and abundant species. Behavioral evaluation has shown that HFHC, NC + TAA, and HFHC + TAA displayed a worsened execution when discriminating the new object. Also, NC + TAA and HFHC + TAA were not capable of recognizing the changes in place of the object. Furthermore, working memory was affected in HFHC and HFHC + TAA groups, whereas the NC + TAA group displayed a significant delay in the acquisition. Brain oxidative metabolism changes were observed in the prefrontal, retrosplenial, and perirhinal cortices, as well as the amygdala and mammillary bodies. Besides, groups administered with thioacetamide presented an increased oxidative metabolic activity in the adrenal glands. These results highlight the importance of cross-comparison along the liver spectrum to understand the different gut–microbiota–brain changes. Furthermore, our data point out specific gut microbiota targets to design more effective treatments, though the liver–gut–brain axis focused on specific stages of liver disease.

Olive- and Coconut-Oil-Enriched Diets Decreased Secondary Bile Acids and Regulated Metabolic and Transcriptomic Markers of Brain Injury in the Frontal Cortexes of NAFLD Pigs

The objective of this study was to investigate the effect of dietary fatty acid (FA) saturation and carbon chain length on brain bile acid (BA) metabolism and neuronal number in a pig model of pediatric NAFLD. Thirty 20-day-old Iberian pigs, pair-housed in pens, were randomly assigned to receive one of three hypercaloric diets for 10 weeks: (1) lard-enriched (LAR; n = 5 pens), (2) olive-oil-enriched (OLI, n = 5), and (3) coconut-oil-enriched (COC; n = 5). Pig behavior and activity were analyzed throughout the study. All animals were euthanized on week 10 and frontal cortex (FC) samples were collected for immunohistochemistry, metabolomic, and transcriptomic analyses. Data were analyzed by multivariate and univariate statistics. No differences were observed in relative brain weight, neuronal number, or cognitive functioning between diets. Pig activity and FC levels of neuroprotective secondary BAs and betaine decreased in the COC and OLI groups compared with LAR, and paralleled the severity of NAFLD. In addition, OLI-fed pigs showed downregulation of genes involved in neurotransmission, synaptic transmission, and nervous tissue development. Similarly, COC-fed pigs showed upregulation of neurogenesis and myelin repair genes, which caused the accumulation of medium-chain acylcarnitines in brain tissue. In conclusion, our results indicate that secondary BA levels in the FCs of NAFLD pigs are affected by dietary FA composition and are associated with metabolic and transcriptomic markers of brain injury. Dietary interventions that aim to replace saturated FAs by medium-chain or monounsaturated FAs in high-fat hypercaloric diets may have a negative effect on brain health in NAFLD patients.

Association of Nonalcoholic Fatty Liver Disease and Fibrosis With Incident Dementia and Cognition: The Rotterdam Study

BACKGROUND AND OBJECTIVES

Nonalcoholic fatty liver disease (NAFLD) might affect brain health via the so-called liver-brain axis. Whether this results in an increased risk for dementia remains unclear. Therefore, we investigated the association of NAFLD and fibrosis with incident dementia and cognition among the elderly.

METHODS

We performed longitudinal and cross-sectional analyses within the Rotterdam Study, an ongoing prospective cohort. Participants visiting between 1997 and 2002 with available fatty liver index (FLI) (set 1) or participants visiting between 2009 and 2014 with abdominal ultrasound (set 2) and liver stiffness (set 3) were included. Exclusion criteria were secondary causes for steatosis, prevalent dementia, and missing alcohol data. NAFLD was defined as FLI ≥60 or steatosis on ultrasound and fibrosis as liver stiffness ≥8.0 kPa. Dementia was defined according to the DSM-III-R. Associations between NAFLD, fibrosis, or liver stiffness and incident dementia were quantified using Cox regression. Finally, the association between NAFLD and cognitive function was assessed cross-sectionally.

RESULTS

Set 1 included 3,975 participants (age 70 years, follow-up 15.5 years), set 2 4,577 participants (age 69.9 years, follow-up 5.7 years), and set 3 3,300 participants (age 67.6 years, follow-up 5.6 years). NAFLD and fibrosis were consistently not associated with an increased risk for dementia (NAFLD based on ultrasound, hazard rate [HR] 0.84, 95% CI 0.61-1.16; NAFLD based on FLI, HR 0.92, 95% CI 0.69-1.22; fibrosis, HR 1.07, 95% CI 0.58-1.99) in fully adjusted models. Of interest, NAFLD was associated with a significantly decreased risk for incident dementia until 5 years after FLI assessment (HR 0.48; 95% CI 0.24-0.94). Moreover, NAFLD was not associated with worse cognitive function, covering several domains.

CONCLUSIONS

NAFLD and fibrosis were not associated with an increased risk for incident dementia, nor was NAFLD associated with impaired cognitive function. In contrast, NAFLD was even protective in the first 5 years of follow-up, hinting toward NAFLD regression before dementia onset.

TRIAL REGISTRATION INFORMATION

Clinical Trial Number: NTR6831.

Depression and non-alcoholic fatty liver disease: Association and potential mechanisms

Non-alcoholic fatty liver disease (NAFLD) is the most common chronic liver disease in the world, and is closely related to the high incidence of obesity, metabolic syndrome, type 2 diabetes, arteriosclerotic cardiovascular disease, and colorectal tumor. Depression is a common mental disorder that is characterized by high incidence, high recurrence rate, high disability rate, and high suicide rate, which has serious harm to patients' physical and mental health, reduce the quality of life of patients. In recent years, as more and more attention has been paid to mental health of NAFLD patients, the relationship between NAFLD and depression has become one of the hot research topics. Studies have shown that the incidence of depression in NAFLD patients is higher than that in non-NAFLD patients, and the incidence of NAFLD in depressed patients is also higher. Some research results have been published on the mechanism of comorbidity between the two. This paper reviews the research progress on the correlation and common mechanism between NAFLD and depression, aiming to lay a foundation for further research on the comorbidities of NAFLD and depression, and provide a basis and research direction for the diagnosis and treatment of patients with both comorbidities.

Non-alcoholic Fatty Liver Disease and Longitudinal Cognitive Changes in Middle-Aged and Elderly Adults

Background and Purpose

Non-alcoholic fatty liver disease (NAFLD) and cognitive impairment are common aging-related disorders. This study aims to explore the changes of cognitive function in middle-aged and elderly population with NAFLD from a Jidong impairment cohort.

Methods

A total of 1,651 middle-aged and elderly participants (&gt;40 years) without cognitive impairment were recruited into the current study in 2015 and were followed up until to 2019. Abdominal ultrasonography was used for diagnosis of NAFLD. Global cognitive function was assessed with the Mini-Mental State Examination (MMSE). Cognitive impairment was defined as a score &lt;18 for illiterates, a score &lt;21 for primary school graduates, and a score &lt;25 for junior school graduates or above. Multivariable regression analysis was performed to evaluate the association between NAFLD and the four-year cognitive changes.

Results

Out of 1,651 participants, 795 (48.2%) of them had NAFLD in 2015. Cognitive impairment occurred in 241 (14.6%) participants in 2019. Patients with NAFLD had higher 4-year incidence of cognitive impairment than non-NAFLD patients did (17.7 vs. 11.7%, p &lt; 0.001). Multivariable linear regression analysis showed significant association of baseline NAFLD with lower MMSE score in 2019 (β = −0.36, p &lt; 0.05). Multivariable logistic analysis found that the adjusted odds ratio (OR) with 95% confidence interval (CI) of baseline NAFLD was 1.45 (1.00–2.11) for cognitive impairment in 2019 (p = 0.05). We also identified effects of baseline NAFLD on subsequent cognitive impairment as modified by age (interaction p &lt; 0.01) and carotid stenosis (interaction p = 0.05) but not by gender.

Conclusions

NAFLD is associated with cognitive decline, especially in middle-aged and with carotid stenosis population.

Is there an association between non-alcoholic fatty liver disease and cognitive function? A systematic review

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) is represented as the most common liver disease worldwide. NAFLD is associated with metabolic risk factors underpinned by insulin resistance, inflammation and endothelial dysfunction, leading to extrahepatic changes in central nervous diseases such as cognitive impairment, Alzheimer's disease and dementia. The aim of the review is to explore the association between NAFLD and cognitive function.

METHODS

Using the PRISMA guidelines, a systematic electronic literature search was conducted in four databases: MEDLINE, PsychINFO, Embase and CINAHL from inception until March 2021. Neuropsychological tests utilised within each study were grouped into relevant cognitive domains including 'general cognition', 'reasoning', 'mental speed, attention and psychomotor speed', 'memory and learning', 'language', 'visuospatial perception' and 'ideas, abstraction, figural creations and mental flexibility'.

RESULTS

Eleven observational studies that involved 7978 participants with a mean age of 51 years were included. Those with NAFLD had poor cognitive performance in three cognitive domains, including 'general cognition', 'mental speed, attention and psychomotor speed', and 'ideas, abstraction, figural creations and mental flexibility'.

CONCLUSION

The observed results from the 11 included studies showed that NAFLD was associated with lower cognitive performance across several domains. However, studies conducted to date are limited to observational designs and are heterogeneous with varying diagnostic tools used to assess cognitive function.

TRIAL REGISTRATION

PROSPERO Registration: CRD42020161640 .

Association between lipid metabolism and cognitive function in patients with schizophrenia

BACKGROUND

The association between blood lipids and cognitive function in schizophrenia is still controversial. Thus, the present study aimed to verify the association between various lipid parameters and cognitive impairment in schizophrenic patients and potential lipid pathways.

METHODS

A total of 447 adult inpatients with schizophrenia were divided into cognitive normal and cognitive impairment groups based on the Mini-Mental State Examination with a cut-off of 26. The blood lipid parameters were defined as abnormal levels based on the guideline. The liquid chromatography-mass spectrometry method was used to preliminarily explore the potential lipid metabolism pathway associated with cognitive impairment.

RESULTS

There were 368 (82.3%) patients who had cognitive impairment. Herein, apolipoprotein B was positively associated with cognitive function in overall patients and age (≥45 and <45 years) and sex subgroups. After excluding patients with hypertension and diabetes, ApoB was still significantly associated with cognitive function in all the patients. The associations between other lipid parameters, including non-high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol and triglyceride, and cognitive impairment were heterogeneous in age and sex subgroups. In contrast, total cholesterol and apolipoprotein A1 were not significantly associated with cognitive impairment. Metabolomics analysis showed that metabolic pathway mainly involved sphingolipid metabolism. Meanwhile, sphinganine and 3-dehydrosphinganine were positively correlated with lipid parameters and decreased in patients with cognitive impairment as compared to those with normal cognition.

CONCLUSIONS

The present study suggests a positive association between lipids and cognitive function in schizophrenic patients and needs to be further verified by a prospective study.

Organ-on-a-Chip for Studying Gut-Brain Interaction Mediated by Extracellular Vesicles in the Gut Microenvironment

Extracellular vesicles (EVs) are a group of membrane vesicles that play important roles in cell-to-cell and interspecies/interkingdom communications by modulating the pathophysiological conditions of recipient cells. Recent evidence has implied their potential roles in the gut–brain axis (GBA), which is a complex bidirectional communication system between the gut environment and brain pathophysiology. Despite the evidence, the roles of EVs in the gut microenvironment in the GBA are less highlighted. Moreover, there are critical challenges in the current GBA models and analyzing techniques for EVs, which may hinder the research. Currently, advances in organ-on-a-chip (OOC) technologies have provided a promising solution. Here, we review the potential effects of EVs occurring in the gut environment on brain physiology and behavior and discuss how to apply OOCs to research the GBA mediated by EVs in the gut microenvironment.

Cerebrolysin Prevents Brain Injury in a Mouse Model of Liver Damage

Liver damage can lead to secondary organ damage by toxic substances and catabolic products accumulation which can increase the permeability of blood-brain barrier, leading to cognitive impairment. The only real treatment for end stage liver failure is grafting. With some, but not all, neurological symptoms subsiding after transplantation, the presence of brain damage can impair both the short and long-term outcome. We tested if Cerebrolysin can prevent brain injury in an experimental model of non-viral liver damage in mice. Behavior, abdominal ultrasound evaluation and immunohistochemistry were used to evaluate the animals. No ultrasound or behavior differences were found between the control and treated animals, with both groups displaying more anxiety and no short-term memory benefit compared to sham mice. Cerebrolysin treatment was able to maintain a normal level of cortical NeuN+ cells and induced an increase in the area occupied by BrdU+ cells. Surprisingly, no difference was observed when investigating Iba1+ cells. With neurological complications of end-stage liver disease impacting the rehabilitation of patients receiving liver grafts, a neuroprotective treatment of patients on the waiting lists might improve their rehabilitation outcome by ensuring a minimal cerebral damage.

Protective effect of quercetin against the metabolic dysfunction of glucose and lipids and its associated learning and memory impairments in NAFLD rats

BACKGROUND

Quercetin (QUE) is a flavonol reported with anti-inflammatory and antioxidant activities, and previous results from the group of this study have demonstrated its neuroprotective effect against lipopolysaccharide-induced neuropsychiatric injuries. However, little is known about its potential effect on neuropsychiatric injuries induced or accompanied by metabolic dysfunction of glucose and lipids.

METHODS

A nonalcoholic fatty liver disease (NAFLD) rat model was induced via a high-fat diet (HFD), and glucolipid parameters and liver function were measured. Behavioral performance was observed via the open field test (OFT) and the Morris water maze (MWM). The plasma levels of triggering receptor expressed on myeloid cells-1 (TREM1) and TREM2 were measured via enzyme-linked immunosorbent assay (ELISA). The protein expression levels of Synapsin-1 (Syn-1), Synaptatogmin-1 (Syt-1), TREM1 and TREM2 in the hippocampus were detected using western blotting. Morphological changes in the liver and hippocampus were detected by HE and Oil red or silver staining.

RESULTS

Compared with the control rats, HFD-induced NAFLD model rats presented significant metabolic dysfunction, hepatocyte steatosis, and impaired learning and memory ability, as indicated by the increased plasma concentrations of total cholesterol (TC) and triglyceride (TG), the impaired glucose tolerance, the accumulated fat droplets and balloon-like changes in the liver, and the increased escaping latency but decreased duration in the target quadrant in the Morris water maze. All these changes were reversed in QUE-treated rats. Moreover, apart from improving the morphological injuries in the hippocampus, treatment with QUE could increase the decreased plasma concentration and hippocampal protein expression of TREM1 in NAFLD rats and increase the decreased expression of Syn-1 and Syt-1 in the hippocampus.

CONCLUSIONS

These results suggested the therapeutic potential of QUE against NAFLD-associated impairment of learning and memory, and the mechanism might involve regulating the metabolic dysfunction of glucose and lipids and balancing the protein expression of synaptic plasticity markers and TREM1/2 in the hippocampus.

Anatomical Brain Changes and Cognitive Abilities in Patients with Obstructive Sleep Apnea Syndrome and Nonalcoholic Fatty Liver Disease

Obstructive sleep apnea (OSA) is characterized by repetitive complete or partial collapse of the upper airway and reduction of airflow during sleep. It is associated with significantly increased daytime muscle sympathetic nerve activity thought to result from the repetitive intermittent periods of hypoxemia during sleep and brain alterations that are likely to result. Different brain regions are affected by subsequent hypoxia/anoxia. Neurodegenerative processes result in measurable atrophy of cortical gray matter in the temporal lobes and posterior cingulate cortex, as well as in subcortical structures such as the hippocampus, amygdala, and thalamus. This study involved a group of firstly diagnosed, therapy-naive, nonalcoholic fatty liver disease (NAFLD) patients, out of which 144 (96 males and 48 females), aged 34-57 (mean 47.88 ± 6.07), satisfied the recruiting criteria for the study and control groups. All the patients underwent MRI scanning, polysomnography testing, and cognitive evaluation. Cognitively, worse results were obtained in the group with OSA (p < 0.05) and NAFLD (p=0.047). A significant decrease in volumes of cortical and subcortical structures was revealed (p < 0.001). In conclusion, brain deterioration followed by cognitive impairment is, most likely, the result of intermittent hypoxia and anoxia episodes that initiate the domino process of deteriorating biochemical reactions in the brain.

Associations between nut intake, cognitive function and non-alcoholic fatty liver disease (NAFLD) in older adults in the United States: NHANES 2011-14

BACKGROUND

Nuts are nutrient-rich and reported to provide some cognitive and cardiometabolic health benefits, but limited studies have focused on older adults. This study investigated the cross-sectional relationship between habitual nut intake, dietary pattern and quality, cognition and non-alcoholic fatty liver disease (NAFLD) in older adults.

METHODS

Older adults (≥ 60 years) from the NHANES 2011-12 and 2013-14 cohorts, who had complete data on cognitive function (as CERAD total, delayed recall, animal fluency and digit-symbol substitution test) and variables to calculate the Fatty Liver Index (FLI), an indicator of NAFLD, were included (n = 1848). Nut intake and diet quality (Healthy Eating Index 2015) were determined using two 24-hour diet recalls. Participants were categorised into one of four groups based on their habitual nut intake: non-consumers (0 g/d), low intake (0.1-15.0 g/d), moderate intake (15.1-30.0 g/d) or met recommendation (> 30 g/d), with all outcomes compared between these nut intake groups.

RESULTS

Cognitive scores of older adults were the lowest in non-consumers and significantly highest in the moderate intake group, with no further increase in those who consumed nuts more than 30 g/d (p < 0.007). FLI was the lowest among older adults with moderate nut intake but the associations disappeared after adjusting for covariates (p = 0.329). Moderate nut intake was also associated with better immediate and delayed memory in older adults with high risk of NAFLD (FLI ≥ 60) (B = 1.84 and 1.11, p < 0.05 respectively). Higher nutrient intake and better diet quality (p < 0.001) were seen with higher nut intake but did not influence energy from saturated fat intake. Factor analysis revealed 'Nuts and oils' as one of the four major dietary patterns associated with better cognition and lower FLI scores.

CONCLUSIONS

Moderate nut intake (15.1-30.0 g/d) may be sufficient for better cognitive performance, but not NAFLD risk of older adults in the US.

PCSK9 and the Gut-Liver-Brain Axis: A Novel Therapeutic Target for Immune Regulation in Alcohol Use Disorder

Alcohol use disorder (AUD) is a chronic relapsing disorder characterized by an impaired ability to control or stop alcohol intake and is associated with organ damage including alcohol-associated liver disease (ALD) and progressive neurodegeneration. The etiology of AUD is complex, but organ injury due to chronic alcohol use can be partially attributed to systemic and local inflammation along the gut-liver-brain axis. Excessive alcohol use can result in translocation of bacterial products into circulation, increased expression of pro-inflammatory cytokines, and activation of immune cells, including macrophages and/or microglia in the liver and brain. One potential mediator of this alcohol-induced inflammation is proprotein convertase subtilisin/kexin type 9 (PCSK9). PCSK9 is primarily known for its regulation of plasma low-density lipoprotein cholesterol but has more recently been shown to influence inflammatory responses in the liver and brain. In rodent and post-mortem brain studies, chronic alcohol use altered methylation of the PCSK9 gene and increased expression of PCSK9 in the liver and cerebral spinal fluid. Additionally, PCSK9 inhibition in a rat model of ALD attenuated liver inflammation and steatosis. PCSK9 may play an important role in alcohol-induced pathologies along the gut-liver-brain axis and may be a novel therapeutic target for AUD-related liver and brain inflammation.

High-Fat Diet Modulates Hepatic Amyloid β and Cerebrosterol Metabolism in the Triple Transgenic Mouse Model of Alzheimer's Disease

Obesity and diabetes are strongly associated not only with fatty liver but also cognitive dysfunction. Moreover, their presence, particularly in midlife, is recognized as a risk factor for Alzheimer's disease (AD). AD, the most common cause of dementia, is increasingly considered as a metabolic disease, although underlying pathogenic mechanisms remain unclear. The liver plays a major role in maintaining glucose and lipid homeostasis, as well as in clearing the AD neuropathogenic factor amyloid-β (Aβ) and in metabolizing cerebrosterol, a cerebral-derived oxysterol proposed as an AD biomarker. We hypothesized that liver impairment induced by obesity contributes to AD pathogenesis. We show that the AD triple transgenic mouse model (3xTg-AD) fed a chow diet presents a hepatic phenotype similar to nontransgenic controls (NTg) at 15 months of age. A high-fat diet (HFD), started at the age of 6 months and continued for 9 months, until sacrifice, induced hepatic steatosis in NTg, but not in 3xTg-AD mice, whereas HFD did not induce changes in hepatic fatty acid oxidation, de novo lipogenesis, and gluconeogenesis. HFD-induced obesity was associated with a reduction of insulin-degrading enzyme, one of the main hepatic enzymes responsible for Aβ clearance. The hepatic rate of cerebrosterol glucuronidation was lower in obese 3xTg-AD than in nonobese controls (P < 0.05) and higher compared with obese NTg (P < 0.05), although circulating levels remained unchanged. Conclusion: Modulation of hepatic lipids, Aβ, and cerebrosterol metabolism in obese 3xTg-AD mice differs from control mice. This study sheds light on the liver-brain axis, showing that the chronic presence of NAFLD and changes in liver function affect peripheral AD features and should be considered during development of biomarkers or AD therapeutic targets.

Cognitive Dysfunction in Non-Alcoholic Fatty Liver Disease-Current Knowledge, Mechanisms and Perspectives

Non-alcoholic fatty liver disease (NAFLD) has emerged as the hepatic component of the metabolic syndrome and now seemingly affects one-fourth of the world population. Features associated with NAFLD and the metabolic syndrome have frequently been linked to cognitive dysfunction, i.e. systemic inflammation, vascular dysfunction, and sleep apnoea. However, emerging evidence suggests that NAFLD may be a cause of cognitive dysfunction independent of these factors. NAFLD in addition exhibits dysbiosis of the gut microbiota and impaired urea cycle function, favouring systemic ammonia accumulation and further promotes systemic inflammation. Such disruption of the gut–liver–brain axis is essential in the pathogenesis of hepatic encephalopathy, the neuropsychiatric syndrome associated with progressive liver disease. Considering the growing burden of NAFLD, the morbidity from cognitive impairment is expected to have huge societal and economic impact. The present paper provides a review of the available evidence for cognitive dysfunction in NAFLD and outlines its possible mechanisms. Moreover, the clinical challenges of characterizing and diagnosing cognitive dysfunction in NAFLD are discussed.

The interaction between brain and liver regulates lipid metabolism in the TBI pathology

To shed light on the impact of systemic physiology on the pathology of traumatic brain injury (TBI), we examine the effects of TBI (concussive injury) and dietary fructose on critical aspects of lipid homeostasis in the brain and liver of young-adult rats. Lipids are integral components of brain structure and function, and the liver has a role on the synthesis and metabolism of lipids. Fructose is mainly metabolized in the liver with potential implications for brain function. Lipidomic analysis accompanied by unbiased sparse partial least squares discriminant analysis (sPLS-DA) identified lysophosphatidylcholine (LPC) and cholesterol ester (CE) as the top lipid families impacted by TBI and fructose in the hippocampus, and only LPC (16:0) was associated with hippocampal-dependent memory performance. Fructose and TBI elevated liver pro-inflammatory markers, interleukin-1α (IL-1α), Interferon-γ (IFN-γ) that correlated with hippocampal-dependent memory dysfunction, and monocyte chemoattractant protein-1 (MCP-1) positively correlated with LPC levels in the hippocampus. The effects of fructose were more pronounced in the liver, in agreement with the role of liver on fructose metabolism and suggest that fructose could exacerbate liver inflammation caused by TBI. The overall results indicate that TBI and fructose interact to influence systemic and central inflammation by engaging liver lipids. The impact of TBI and fructose diet on the periphery provides a therapeutic target to counteract the TBI pathogenesis.

Interaction Mechanisms Between Major Depressive Disorder and Non-alcoholic Fatty Liver Disease

Major depressive disorder (MDD), which is highly associated with non-alcoholic fatty liver disease (NAFLD), has complex pathogenic mechanisms. However, a limited number of studies have evaluated the mutual pathomechanisms involved in MDD and NAFLD development. Chronic stress-mediated elevations in glucocorticoid (GC) levels play an important role in the development of MDD-related NAFLD. Elevated GC levels can induce the release of inflammatory factors and changes in gut permeability. Elevated levels of inflammatory factors activate the hypothalamic-pituitary-adrenal (HPA) axis, which further increases the release of GC. At the same time, changes in gut permeability promote the release of inflammatory factors, which results in a vicious circle among the three, causing disease outbreaks. Even though the specific role of the thyroid hormone (TH) in this pathogenesis has not been fully established, it is highly correlated with MDD and NAFLD. Therefore, changing lifestyles and reducing psychological stress levels are necessary measures for preventing MDD-related NAFLD. Among them, GC inhibitors and receptor antagonists may be key in the alleviation of early and mid-term disease progression. However, combination medications may be important in late-stage diseases, but they are associated with various side effects. Traditional Chinese medicines have been shown to be potential therapeutic alternatives for such complex diseases.

Hepatic encephalopathy: Novel insights into classification, pathophysiology and therapy

Hepatic encephalopathy (HE) is a frequent and serious complication of both chronic liver disease and acute liver failure. HE manifests as a wide spectrum of neuropsychiatric abnormalities, from subclinical changes (mild cognitive impairment) to marked disorientation, confusion and coma. The clinical and economic burden of HE is considerable, and it contributes greatly to impaired quality of life, morbidity and mortality. This review will critically discuss the latest classification of HE, as well as the pathogenesis and pathophysiological pathways underlying the neurological decline in patients with end-stage liver disease. In addition, management strategies, diagnostic approaches, currently available therapeutic options and novel treatment strategies are discussed.

Complications of Non-Alcoholic Fatty Liver Disease in Extrahepatic Organs

Non-alcoholic fatty liver disease (NAFLD) is now recognized as the most common chronic liver disease worldwide, along with the concurrent epidemics of metabolic syndrome and obesity. Patients with NAFLD have increased risks of end-stage liver disease, hepatocellular carcinoma, and liver-related mortality. However, the largest cause of death among patients with NAFLD is cardiovascular disease followed by extrahepatic malignancies, whereas liver-related mortality is only the third cause of death. Extrahepatic complications of NAFLD include chronic kidney disease, extrahepatic malignancies (such as colorectal cancer), psychological dysfunction, gastroesophageal reflux disease, obstructive sleep apnea syndrome, periodontitis, hypothyroidism, growth hormone deficiency, and polycystic ovarian syndrome. The objective of this narrative review was to summarize recent evidences about extrahepatic complications of NAFLD, with focus on the prevalent/incident risk of such diseases in patients with NAFLD. To date, an appropriate screening method for extrahepatic complications has not yet been determined. Collaborative care with respective experts seems to be necessary for patient management because extrahepatic complications can occur across multiple organs. Further studies are needed to reveal risk profiles at baseline and to determine an appropriate screening method for extrahepatic diseases.

Pitch Processing Can Indicate Cognitive Alterations in Chronic Liver Disease: An fNIRS Study

Early detection and evaluation of cognitive alteration in chronic liver disease is important for predicting the subsequent development of hepatic encephalopathy. While visuomotor tasks have been rigorously employed for cognitive evaluation in chronic liver disease, there is a paucity of auditory processing task. Here we focused on auditory perception and examined behavioral and haemodynamic responses to a melodic contour identification task (CIT) to compare cognitive abilities in patients with chronic liver disease (CLD, N = 30) and healthy controls (N = 25). Further, we used support vector machines to examine the optimal combination of channels of functional near-infrared spectroscopy that can classify cognitive alterations in CLD. Behavioral findings showed that CIT performance was significantly worse in the patient group and CIT significantly correlated with neurocognitive evaluation (i.e., number connection test, digit span test). The findings indicated that CIT can measure auditory cognitive capacity and its difference existing between patient group and healthy controls. Additionally, optimal subsets classified the 16-dimensional haemodynamic data with 78.35% classification accuracy, yielding markers of cognitive alterations in the prefrontal regions (CH6, CH7, CH10, CH13, CH14, and CH16). The results confirmed the potential use of behavioral as well as haemodynamic responses to music perception as an alternative or supplementary method for evaluating cognitive alterations in chronic liver disease.