Association of Peripheral Interleukin-6 with Global Cognitive Decline in Non-demented Adults: A Meta-Analysis of Prospective Studies

Aging, sex, metabolic and life experience factors: Contributions to neuro-inflammaging in Alzheimer's disease research

Alzheimer's disease (AD) is prevalent around the world, yet our understanding of the disease is still very limited. Recent work suggests that the cornerstone of AD may include the inflammation that accompanies it. Failure of a normal pro-inflammatory immune response to resolve may lead to persistent central inflammation that contributes to unsuccessful clearance of amyloid-beta plaques as they form, neuronal death, and ultimately cognitive decline. Individual metabolic, and dietary (lipid) profiles can differentially regulate this inflammatory process with aging, obesity, poor diet, early life stress and other inflammatory factors contributing to a greater risk of developing AD. Here, we integrate evidence for the interface between these factors, and how they contribute to a pro-inflammatory brain milieu. In particular, we discuss the importance of appropriate polyunsaturated fatty acids (PUFA) in the diet for the metabolism of specialised pro-resolving mediators (SPMs); raising the possibility for dietary strategies to improve AD outlook.

Dietary Inflammatory Index and Cognitive Function: Findings from a Cross-Sectional Study in Obese Chinese Township Population from 45 to 75 Years

Background and Objective

Cognitive dysfunction is highly prevalent in obese people, and food is a key factor in obesity, and dietary inflammatory index (DII) can reflect whether diet has anti-inflammatory or pro-inflammatory potential. In addition, dietary fatty acid consumption is linked to inflammation, obesity, and cognitive impairment. Erythrocyte membrane fatty acids can reflect dietary fatty acid intake. Our hypothesis was that erythrocyte membrane fatty acids might have a significant impact on the relationship between DII and cognition in obese individuals, and we designed experiments to test the hypothesis.

Methods

In three villages in Beijing, we collected 579 respondents from individuals 45 to 75 years old and categorized them by body mass index. The Montreal Cognitive Assessment (MoCA) score and DII score was calculated and gas chromatography was used to measure the proportion of erythrocyte membrane fatty acids. The relationship between the DII score and cognition was examined using multiple linear regression and binary logistic regression. Mediation analysis can help to understand the causal chain between variables, deeply explore the internal relationship and mechanism of action between variables. So a multiple chain mediation model was developed to investigate the mediating factors between the DII score and cognitive association.

Results

According to adjusted linear regression, higher DII scores were linked to lower MoCA scores in the obese group. The negative correlation between DII score and cognitive function score remains in binary linear regression. We discovered through mediation analysis that erythrocyte membrane fatty acids mediate the detrimental link between DII and cognitive function in obese individuals.

Conclusion

We propose that higher DII scores in obese people are associated with a decline in cognitive function. In addition, this effect might be mediated via the fatty acids in the erythrocyte membrane.

Further evidence supporting the role of GTDC1 in glycine metabolism and neurodevelopmental disorders

Copy number variants (CNVs) represent the genetic cause of about 15-20% of neurodevelopmental disorders (NDDs). We identified a ~67 kb de novo intragenic deletion on chromosome 2q22.3 in a female individual showing a developmental encephalopathy characterised by epilepsy, severe intellectual disability, speech delay, microcephaly, and thin corpus callosum with facial dysmorphisms. The microdeletion involved exons 5-6 of GTDC1, encoding a putative glycosyltransferase, whose expression is particularly enriched in the nervous system. In a previous study, a balanced de novo translocation encompassing GTDC1 was reported in a male child with global developmental delay and delayed speech and language development. Based on these premises, we explored the transcriptomic profile of our proband to evaluate the functional consequences of the novel GTDC1 de novo intragenic deletion in relation to the observed neurodevelopmental phenotype. RNA-seq on the proband's lymphoblastoid cell line (LCL) showed expression changes of glycine/serine and cytokine/chemokine signalling pathways, which are related to neurodevelopment and epileptogenesis. Subsequent analysis by ELISA (enzyme-linked immunosorbent assay) and HPLC (high-performance liquid chromatography) revealed increased levels of glycine in the proband's LCL and serum compared to matched controls. Given that an increased level of glycine has been observed in the plasma samples of individuals with Rett syndrome, a condition sharing epilepsy, microcephaly, and intellectual disability with our proband, we proposed that the GTDC1 downregulation is implicated in neurodevelopmental impairment by altering glycine metabolism. Furthermore, our findings expanded the phenotypic spectrum of the novel GTDC1-related condition, including microcephaly and epilepsy among relevant clinical features.

Biopsychosocial contexts influence adult cognitive function concurrently and longitudinally

Background

Cognitive aging is a complex process that impacts human behavior. Identifying the factors that preserve cognitive functioning is a public health priority, given that 20% of the US population will be at least 65 years old in the next decade. Biopsychosocial determinants of cognitive decline across the lifespan are often examined as ecological factors that independently moderate cognitive aging, despite the known complexity surrounding these relationships.

Objective

We aimed to address this gap by exploring the synergistic and simultaneous relationship between risk and protective factors on cognitive functioning.

Method

Using the MIDUS study datasets, we examined the relationships among physiological markers, friendship quality, and global cognition functioning, concurrently and longitudinally over ten years. Our participants included 929 healthy (417 men, 512 women) adults (average age at Time 1: 54.6 ± 11.6 years). Exploratory analyses examining the effects of racial minority status were also conducted.

Results

Cross-sectionally, age, and friendship quality moderated the relationship between vagally-mediated heart rate variability (vm-HRV) and cognition such that younger adults with greater friendship quality had a negative relationship between vm-HRV and cognitive performance; our unexpected finding suggests the heart-brain relationship is sensitive to the biopsychosocial environment. Longitudinally, higher IL-6 levels at Time 1 predicted poorer cognitive performance a decade later, but only among those with greater levels of friendship quality, especially for white-identifying individuals.

Conclusions

The relationships among physiological risk factors, social protective factors and cognitive functioning appear to be temporally different during mid-adulthood. Given many of the whole sample findings were not replicated within the racial minority subgroup, we suggest that these relationships should be examined in a larger and more diverse racial minority sample to determine whether this study lacked the power necessary to detect a relationship or if the relationships are in fact different by racial minority sub-group. In addition, future research should overcome the study's reliance on healthy adults and self-report measures of friendship quality by including adults with pre-existing cognitive impairments, and employing more real-time measures of friendship quality, such as daily diary or ecological momentary assessment.

Adipose tissue as a therapeutic target for vascular damage in Alzheimer's disease

Adipose tissue has recently been recognized as an important endocrine organ that plays a crucial role in energy metabolism and in the immune response in many metabolic tissues. With this regard, emerging evidence indicates that an important crosstalk exists between the adipose tissue and the brain. However, the contribution of adipose tissue to the development of age-related diseases, including Alzheimer's disease, remains poorly defined. New studies suggest that the adipose tissue modulates brain function through a range of endogenous biologically active factors known as adipokines, which can cross the blood-brain barrier to reach the target areas in the brain or to regulate the function of the blood-brain barrier. In this review, we discuss the effects of several adipokines on the physiology of the blood-brain barrier, their contribution to the development of Alzheimer's disease and their therapeutic potential. LINKED ARTICLES: This article is part of a themed issue From Alzheimer's Disease to Vascular Dementia: Different Roads Leading to Cognitive Decline. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v181.6/issuetoc.

Psychological and neurobiological mechanisms involved in the relationship between loneliness and cognitive decline in older adults

Loneliness, among older adults, is one of the risk factors for developing dementia. Still, little is known about the neurobiological and psychological conditions that link loneliness to cognitive decline. The current study investigated several research aims: First, it sought to identify neurobiological and psychological pathways that may account for the relationship between loneliness and decline across several cognitive domains. These pathways included depressive symptoms, total gray matter volume, and conditional analyses of pro-inflammatory cytokines and brain-derived neurotrophic factor (BDNF) expression. Second, it examined loneliness as a predictor of mild cognitive impairment (MCI) and Alzheimer's disease (AD). Third, it sought to determine whether the relationship between loneliness and cognitive decline is sex-specific in older adults. Longitudinal data were collected from 2130 Rush Memory and Aging Project participants. Participants underwent annual cognitive and psychological assessments and neuroimaging procedures every year. BDNF gene expression was measured in the dorsolateral prefrontal cortex, cytokines were measured in serum, and the final consensus clinical diagnosis was identified at the time of death. All linear mixed and multinomial logistic regression models controlled for age at baseline, education, sex, and APOE genotype. Participants were largely women (73 %), and Caucasian (93 %). The average education was 14.93 (SD = 3.34). The average age at baseline was 80.05 (SD = 7.57). Results showed that gray matter volume and depressive symptoms partially mediated the relationship between loneliness and cognitive decline. There was a significant interaction between loneliness and BDNF expression in relation to cognitive decline. Higher levels of BDNF expression was associated with slower decline in semantic memory and visuospatial ability. Finally, the current study also established that higher levels of loneliness was positively associated with the incidence of AD and other dementias. The present findings support the growing literature, which tends to show that the consequence of loneliness goes beyond the feeling of being isolated. Loneliness may induce physiological changes in our brains, leading to cognitive decline. Future research can explore a wide range of biological and psychological expressions of loneliness to clarify how loneliness relates to dementia.

Androgen Deprivation Therapy for Prostate Cancer: Focus on Cognitive Function and Mood

Prostate cancer is the second leading cause of cancer death in men in the United States. Androgen deprivation therapy (ADT) is currently the primary treatment for metastatic prostate cancer, and some studies have shown that the use of anti-androgen drugs is related to a reduction in cognitive function, mood changes, diminished quality of life, dementia, and possibly Alzheimer's disease. ADT has potential physiological effects such as a reduction in white matter integrity and a negative impact on hypothalamic functions due to the lowering of testosterone levels or the blockade of downstream androgen receptor signaling by first- and second-generation anti-androgen drugs. A comparative analysis of prostate cancer patients undergoing ADT and Alzheimer patients identified over 30 shared genes, illustrating common ground for the mechanistic underpinning of the symptomatology. The purpose of this review was to investigate the effects of ADT on cognitive function, mood, and quality of life, as well as to analyze the relationship between ADT and Alzheimer's disease. The evaluation of prostate cancer patient cognitive ability via neurocognitive testing is described. Future studies should further explore the connection among cognitive deficits, mood disturbances, and the physiological changes that occur when hormonal balance is altered.

A glance through the effects of CD4+ T cells, CD8+ T cells, and cytokines on Alzheimer's disease

Alzheimer's disease (AD) is the most common form of dementia. Unfortunately, despite numerous studies, an effective treatment for AD has not yet been established. There is remarkable evidence indicating that the innate immune mechanism and adaptive immune response play significant roles in the pathogenesis of AD. Several studies have reported changes in CD8+ and CD4+ T cells in AD patients. This mini-review article discusses the potential contribution of CD4+ and CD8+ T cells reactivity to amyloid β (Aβ) protein in individuals with AD. Moreover, this mini-review examines the potential associations between T cells, heme oxygenase (HO), and impaired mitochondria in the context of AD. While current mathematical models of AD have not extensively addressed the inclusion of CD4+ and CD8+ T cells, there exist models that can be extended to consider AD as an autoimmune disease involving these T cell types. Additionally, the mini-review covers recent research that has investigated the utilization of machine learning models, considering the impact of CD4+ and CD8+ T cells.

Purpose in life and markers of immunity and inflammation: Testing pathways of episodic memory

OBJECTIVE

This prospective cohort study examines whether purpose in life is associated with markers of immunity and inflammation and tests these markers as mediators between purpose and episodic memory.

METHODS

Participants from the Venous Blood Study of the Health and Retirement Study reported on their purpose in life, had their blood assayed for markers of immunity and inflammation, and were administered an episodic memory task (N = 8999). Regression analyses tested the association between purpose and each marker. Prospective mediation analyses (N = 6092) tested whether these markers measured in 2016 were mediators between purpose measured in 2012/2014 and episodic memory measured in 2018.

RESULTS

Higher purpose in life was associated with lower neutrophil counts (β = -0.08, p < .001), lower ratio of neutrophils/lymphocytes (β = -0.05, p < .001), and lower systemic immune inflammation index (β = -0.04, p < .001); purpose was unrelated to monocyte, platelet, and lymphocyte counts or the ratio of platelets/lymphocytes (all ns). Purpose was associated negatively with c-reactive protein (β = -0.07, p < .001), Interleukin-6 (β = -0.08, p < .001), Interleukin-10 (β = -0.07, p < .001), Interleukin-1ra (β = -0.08, p < .001), and soluble Tumor Necrosis Factor Receptor 1 (sTNFR1; β = -0.10, p < .001); purpose was unrelated to Transforming Growth Factor beta 1. These associations were largely not moderated by age, sex, race, ethnicity, and education. Lower neutrophils, Interleukin-6, and sTNFR1 were associated prospectively with better episodic memory and mediated the association between purpose and episodic memory.

CONCLUSION

Purpose in life is associated with markers of immunity and inflammation, some of which are one mechanism in the pathway between purpose and healthier episodic memory.

Older adults' self-reported prospective memory lapses in everyday life: Connections to inflammation and gender

OBJECTIVE

Limited research has focused on the association between inflammatory markers and features of subjective cognitive functioning among older adults. The present work examined links between inflammation and a specific subjective cognitive report: prospective memory (PM), or our memory for future intentions, such as attending an appointment or taking medication.

METHOD

We assessed self-reported PM lapses using a two-week ecological momentary assessment (EMA) diary protocol via smartphone as well as levels of blood-based inflammation among 231 dementia-free older adults (70-90 years, 66% women) enrolled in the Einstein Aging Study.

RESULTS

Overall, PM lapses were largely unrelated to inflammatory markers. However, a significant gender difference was observed in the link between basal levels of interleukin (IL)-8 and PM lapses: higher levels of basal IL-8 were associated with more PM lapses among men (estimate = 0.98, 95%CI: [0.43, 1.53], p < .001) but not women (estimate = -0.03, 95%CI: [-0.45, 0.39], p = .826). No other significant relationships between PM lapses and basal or stimulated (ex vivo) cytokine levels (IL-1β, IL-4, IL-6, IL-8, IL-10, tumor necrosis factor-alpha [TNF-α]) or C-reactive protein (CRP) emerged.

CONCLUSION

Elevated levels of IL-8 in older men may possibly be an early indicator of neurodegeneration that relates to PM performance. Future studies should continue to examine PM and inflammation across genders to identify possible mechanisms through which these constructs may indicate neurodegeneration and dementia risk.

Resolution of elevated interleukin-6 after surgery is associated with return of normal cognitive function

BACKGROUND

Unresolved surgical inflammation might induce chronic cognitive decline in older adults. Although inflammatory biomarkers have been correlated with perioperative cognitive impairment and delirium, the effects of prolonged inflammation on cognition are not well studied. This prospective cohort study investigated 1-yr dynamics in plasma interleukin-6 levels and executive function.

METHODS

Patients undergoing major surgery (n=170) aged ≥65 yr completed Trail Making Test B and other neuropsychological assessments with plasma interleukin-6 levels collected on postoperative days 1-9 and 90, and at 1-yr. Mixed-effects analyses were conducted for Trail Making Test B (and other assessments), including interleukin-6 levels, time, and additional confounders (fixed effects), and a random effect for participant.

RESULTS

Changes in interleukin-6 levels were associated with changes in Trail Making Test B over 1 yr in a generalised additive model (β=0.074, P<0.001) supporting that unresolved inflammation impaired executive function. This result was robust to confounders, outlier rejection, and fitting to non-linear models. Changes in interleukin-6 levels also correlated with changes in Trail Making Test A and Controlled Oral Word Association Test. Sensitivity analyses conducted on binary definitions of cognitive decline (>1, >1.5, or >2 standard deviations from baseline) were also associated with interleukin-6 changes.

CONCLUSIONS

Delayed resolution of inflammation is associated with cognitive impairment after surgery. Monitoring interleukin-6 might provide an opportunity to intervene with anti-inflammatory therapies in vulnerable patients.

CLINICAL TRIAL REGISTRATION

NCT01980511, NCT03124303.

Associations of neuroinflammatory IL-6 and IL-8 with brain atrophy, memory decline, and core AD biomarkers - in cognitively unimpaired older adults

Concentrations of pro-inflammatory cytokines -interleukin-6 (IL-6) and interleukin-8 (IL-8) - are increased with age and in Alzheimer's disease (AD). It is not clear whether concentrations of IL-6 and IL-8 in the central nervous system predict later brain and cognitive changes over time nor whether this relationship is mediated by core AD biomarkers. Here, 219 cognitively healthy older adults (62-91 years), with baseline cerebrospinal fluid (CSF) measures of IL-6 and IL-8 were followed over time - up to 9 years - with assessments that included cognitive function, structural magnetic resonance imaging, and CSF measurements of phosphorylated tau (p-tau) and amyloid-β (Aβ-42) concentrations (for a subsample). Higher baseline CSF IL-8 was associated with better memory performance over time in the context of lower levels of CSF p-tau and p-tau/Aβ-42 ratio. Higher CSF IL-6 was related to less CSF p-tau changes over time. The results are in line with the hypothesis suggesting that an up-regulation of IL-6 and IL-8 in the brain may play a neuroprotective role in cognitively healthy older adults with lower load of AD pathology.

The intestinal immune system and gut barrier function in obesity and ageing

Obesity and ageing predispose to numerous, yet overlapping chronic diseases. For example, metabolic abnormalities, including insulin resistance (IR) and type 2 diabetes (T2D) are important causes of morbidity and mortality. Low-grade chronic inflammation of tissues, such as the liver, visceral adipose tissue and neurological tissues, is considered a significant contributor to these chronic diseases. Thus, it is becoming increasingly important to understand what drives this inflammation in affected tissues. Recent evidence, especially in the context of obesity, suggests that the intestine plays an important role as the gatekeeper of inflammatory stimuli that ultimately fuels low-grade chronic tissue inflammation. In addition to metabolic diseases, abnormalities in the intestinal mucosal barrier have been linked to a range of other chronic inflammatory conditions, such as neurodegeneration and ageing. The flow of inflammatory stimuli from the gut is in part controlled by local immunological inputs impacting the intestinal barrier. Here, we will review the impact of obesity and ageing on the intestinal immune system and its downstream consequences on gut barrier function, which is strongly implicated in the pathogenesis of obesity and age-related diseases. In particular, we will discuss the effects of age-related intestinal dysfunction on neurodegenerative diseases.

Alteration of Blood Immune Biomarkers in MCI Patients with Different APOE Genotypes after Cognitive Training: A 1 Year Follow-Up Cohort Study

Many studies aim to detect the early phase of dementia. One of the major ways to achieve this is to identify corresponding biomarkers, particularly immune blood biomarkers. The objective of this study was to identify such biomarkers in patients with mild cognitive impairment (MCI) in an experiment that included cognitive training. A group of patients with MCI diagnoses over the age of 65 participated in the study (n = 136). Measurements of cognitive functions (using the Mini-Mental State Examination scale and Montreal Cognitive Assessment) and determination of 27 serum biomarkers were performed twice: on the first visit and on the second visit, one year after the cognitive training. APOE genotypes were also determined. Concentrations of EGF (F = 17; p = 0.00007), Eotaxin (F = 7.17; p = 0.008), GRO (F = 13.42; p = 0.0004), IL-8 (F = 8.16; p = 0.005), MCP-1 (F = 13.46; p = 0.0001) and MDC (F = 5.93; p = 0.016) increased after the cognitive training in MCI patients. All these parameters except IL-8 demonstrated a weak correlation with other immune parameters and were poorly represented in the principal component analysis. Differences in concentrations of IP-10, FGF-2, TGFa and VEGF in patients with MCI were associated with APOE genotype. Therefore, the study identified several immune blood biomarkers that could potentially be associated with changes in cognitive function.

Akkermansia muciniphila, which is enriched in the gut microbiota by metformin, improves cognitive function in aged mice by reducing the proinflammatory cytokine interleukin-6

BACKGROUND

Metformin, a type 2 diabetes treatment, improves the cognitive function of aged mice; however, whether the protective effects of metformin on cognitive function in aged mice are associated with the gut microbiome is poorly understood. Although some studies suggest that the gut microbe composition influences cognitive function and that manipulating the gut microbiota might protect against age-related cognitive dysfunction, there is no direct evidence to validate that the gut microbiota mediates the effect of metformin on cognitive improvement.

RESULTS

In this study, we show that the gut microbiota is altered by metformin, which is necessary for protection against ageing-associated cognitive function declines in aged mice. Mice treated with antibiotics did not exhibit metformin-mediated cognitive function protection. Moreover, treatment with Akkermansia muciniphila, which is enriched by metformin, improved cognitive function in aged mice. Mechanistically, A. muciniphila decreased pro-inflammatory-associated pathways, particularly that of the pro-inflammatory cytokine interleukin (IL)-6, in both the peripheral blood and hippocampal profiles, which was correlated with cognitive function improvement. An IL-6 antibody protected cognitive function, and an IL-6 recombinant protein abolished the protective effect of A. muciniphila on cognitive function in aged mice.

CONCLUSION

This study reveals that A. muciniphila, which is mediated in the gut microbiota by metformin, modulates inflammation-related pathways in the host and improves cognitive function in aged mice by reducing the pro-inflammatory cytokine IL-6. Video Abstract.

Yoga Impacts Cognitive Health: Neurophysiological Changes and Stress Regulation Mechanisms

Yoga, a physical and contemplative practice, offers the practitioner a unique mind-body exercise experience demonstrating preliminary efficacy in improving cognitive health. We examine the evidence for underlying mechanisms that explain the yoga-cognition relationship in healthy older adults. The cognitive benefits of yoga may be the result of improved stress regulation and neurocognitive resource efficiency that facilitate bidirectional brain-body communication.

The Mediating Role of Biomarkers in the Association Between Subjective Aging and Episodic Memory

OBJECTIVES

Subjective aging, indexed by subjective age and self-perceptions of aging (SPA), is consistently related to cognition in adulthood. The present study examined whether blood biomarkers mediate the longitudinal associations between subjective aging indices and memory.

METHODS

Data of 5,369 individuals aged 50-94 years (mean = 66.89 years, SD = 9.22; 60% women) were drawn from the Health and Retirement Study (HRS). Subjective age, SPA, and demographic factors were assessed in 2012/2014. Interleukin-6, C-reactive protein, albumin, cystatin C, N-terminal pro B-type natriuretic peptide (NT-proBNP), fasting glucose, Vitamin D, hemoglobin, red cells distribution width, and epigenetic aging were assessed as part of the HRS Venuous Blood Study in 2016. Memory was measured in 2018. The mediators (except for epigenetic aging, which was assessed in a subsample) were tested simultaneously in models that accounted for demographic covariates.

RESULTS

An older subjective age was related to worse memory partially through higher fasting glucose, higher cystatin C, higher NT-proBNP, and accelerated epigenetic aging. Negative SPA was related to worse memory through lower Vitamin D3, higher fasting glucose, higher cystatin C, higher NT-proBNP, and accelerated epigenetic aging. The biomarkers explained between 2% and 10% of subjective age and between 1% and 8% of SPA associations with memory. Additional analysis revealed that biomarkers continued to be significant mediators when physical inactivity and depressive symptoms were included as additional mediators.

CONCLUSION

The present study adds to existing research on the association between subjective aging and memory by providing new evidence on the biological mediators of this association.

Association of Interleukin-6 and Interleukin-8 with Cognitive Decline in an Asian Memory Clinic Population

BACKGROUND

Neuroinflammation has been postulated to play an important role in cognitive impairment, cognitive decline, and dementia. Inflammatory biomarkers such as interleukin-6 (IL-6) and IL-8 are found to be associated with the neuro-inflammatory process and worse cognitive function. However, it is unknown whether these interleukins are associated with long-term cognitive function.

OBJECTIVE

To investigate the association of baseline IL-6 and IL-8 with cognitive function at baseline as well as its association with cognitive decline over five-year follow-up.

METHODS

387 patients were recruited from an ongoing memory clinic-based study who underwent comprehensive physical, medical, neuropsychological and blood assessments together with brain MRI. IL-6 and IL-8 were measured using LUMINEX assays. The National Institute of Neurological Disorders and Stroke-Canadian Stroke Network neuropsychological battery was used to assess cognitive decline across multiple domains.

RESULTS

Among the 387 (mean age = 72.9 years and 53.7% males) participants, 322 had at least two follow-up assessments and were included in the longitudinal analysis. Negative linear trend associations were found between tertiles of IL-8 with baseline global cognition (p-trend< 0.001), attention (p-trend = 0.005), executive function (p-trend< 0.001), and visuospatial function (p-trend = 0.002) domains. No association was found between baseline IL-8 and cognitive decline. IL-6 was not associated with both baseline and follow-up cognition.

CONCLUSION

IL-8 was associated with worse cognition especially in attention, executive function, and visuospatial function, suggesting the role of neuroinflammation in cognitive impairment. Hence, blood inflammatory biomarkers may be useful indicators in identifying patients at risk of cognitive impairment and warrant consideration for inclusion in treatment trials.

Blood-brain barrier dysfunction promotes astrocyte senescence through albumin-induced TGFβ signaling activation

Blood-brain barrier dysfunction (BBBD) and accumulation of senescent astrocytes occur during brain aging and contribute to neuroinflammation and disease. Here, we explored the relationship between these two age-related events, hypothesizing that chronic hippocampal exposure to the blood-borne protein serum albumin could induce stress-induced premature senescence (SIPS) in astrocytes via transforming growth factor beta 1 (TGFβ) signaling. We found that 1 week of albumin exposure significantly increased TGFβ signaling and senescence marker expression in cultured rat hippocampal astrocytes. These changes were preventable by pharmacological inhibition of the type I TGFβ receptor (TGFβR) ALK5. To study these effects in vivo, we utilized an animal model of BBBD in which albumin was continuously infused into the lateral ventricles of adult mice. Consistent with our in vitro results, 1 week of albumin infusion significantly increased TGFβ signaling activation and the burden of senescent astrocytes in hippocampal tissue. Pharmacological inhibition of ALK5 TGFβR or conditional genetic knockdown of astrocytic TGFβR prior to albumin infusion was sufficient to prevent albumin-induced astrocyte senescence. Together, these results establish a link between TGFβ signaling activation and astrocyte senescence and suggest that prolonged exposure to serum albumin due to BBBD can trigger these phenotypic changes.

Predictors of cognitive decline in older individuals without dementia: An updated meta-analysis

OBJECTIVE

To evaluate the effect of overall peripheral inflammatory levels on cognitive function, we explored the relationship between established biomarkers of peripheral inflammation (circulating C-reactive protein [CRP], interleukin-6 [IL-6], and tumor necrosis factor-α [TNF-α]) and cognitive decline by performing a review of observational studies and creating an updated summary.

METHODS

We included literatures exploring the relationship between peripheral levels of CRP, IL-6, and TNF-α and subsequent cognitive decline, published until July 2022, by searching the following databases: PubMed, Embase, Web of Science, the Cochrane Library, ClinicalTrials, CNKI, and VIP databases. We used random-effects models to pool the odds ratios (ORs) for the risks of subsequent cognitive decline in older adults with high levels of peripheral inflammation. We initially screened out 501 literatures, of which only 17 were ultimately eligible. Overall, there were 19,516 older individuals included in our meta-analysis, and 2134 of them experienced subsequent cognitive change.

RESULTS

Individuals with high levels of peripheral inflammation may have 14% more chance to develop subsequent cognitive decline than those with low levels (OR = 1.14, 95% CI: 1.03-1.27; p < 0.00001). In the subgroup analysis, the incidence of cognitive decline was higher in individuals with high levels of IL-6. This study further demonstrates the link between systemic inflammation and cognitive status.

INTERPRETATION

Detecting CRP, IL-6, and TNF-α in peripheral blood is necessary, as they may become effective indicators for forthcoming cognitive performance.

Molecular Mechanisms of Neuroinflammation in Aging and Alzheimer's Disease Progression

Aging is the most prominent risk factor for late-onset Alzheimer's disease. Aging associates with a chronic inflammatory state both in the periphery and in the central nervous system, the evidence thereof and the mechanisms leading to chronic neuroinflammation being discussed. Nonetheless, neuroinflammation is significantly enhanced by the accumulation of amyloid beta and accelerates the progression of Alzheimer's disease through various pathways discussed in the present review. Decades of clinical trials targeting the 2 abnormal proteins in Alzheimer's disease, amyloid beta and tau, led to many failures. As such, targeting neuroinflammation via different strategies could prove a valuable therapeutic strategy, although much research is still needed to identify the appropriate time window. Active research focusing on identifying early biomarkers could help translating these novel strategies from bench to bedside.

Cogstim: A Shared Decision-making Model to Support Older Adults' Brain Health

The lack of effective treatments for cognitive decline in older adults has led to an interest in the possibility that lifestyle interventions can help to prevent changes in mental functioning and reduce the risk for dementia. Multiple lifestyle factors have been related to risk for decline, and multicomponent intervention studies suggest that changing older adults' behaviors can have a positive impact on their cognition. How to translate these findings into a practical model for clinical use with older adults, however, is not clear. In this Commentary, we propose a shared decision-making model to support clinicians' efforts to promote brain health in older persons. The model organizes risk and protective factors into three broad groups based on their mechanism of action and provides older persons with basic information to allow them to make evidence- and preference-based choices in choosing goals for effective brain health programs. A final component includes basic instruction in behavior change strategies such as goal setting, self-monitoring, and problem-solving. The implementation of the model will support older persons' efforts to develop a personally relevant and effective brainhealthy lifestyle that may help to reduce their risk for cognitive decline.

Signatures of Neuropsychological Test Results in the Long Life Family Study: A Cluster Analysis

BACKGROUND

Discovering patterns of cognitive domains and characterizing how these patterns associate with other risk factors and biomarkers can improve our understanding of the determinants of cognitive aging.

OBJECTIVE

To discover patterns of cognitive domains using neuropsychological test results in Long Life Family Study (LLFS) and characterize how these patterns associate with aging markers.

METHODS

5,086 LLFS participants were administered neuropsychological tests at enrollment. We performed a cluster analysis of six baseline neuropsychological test scores and tested the association between the identified clusters and various clinical variables, biomarkers, and polygenic risk scores using generalized estimating equations and the Chi-square test. We used Cox regression to correlate the clusters with the hazard of various medical events. We investigated whether the cluster information could enhance the prediction of cognitive decline using Bayesian beta regression.

RESULTS

We identified 12 clusters with different cognitive signatures that represent profiles of performance across multiple neuropsychological tests. These signatures significantly correlated with 26 variables including polygenic risk scores, physical and pulmonary functions, and blood biomarkers and were associated with the hazard of mortality (p < 0.01), cardiovascular disease (p = 0.03), dementia (p = 0.01), and skin cancer (p = 0.03).

CONCLUSION

The identified cognitive signatures capture multiple domains simultaneously and provide a holistic vision of cognitive function, showing that different patterns of cognitive function can coexist in aging individuals. Such patterns can be used for clinical intervention and primary care.

Gut microbiota, pathogenic proteins and neurodegenerative diseases

As the world's population ages, neurodegenerative diseases (NDs) have brought a great burden to the world. However, effective treatment measures have not been found to alleviate the occurrence and development of NDs. Abnormal accumulation of pathogenic proteins is an important cause of NDs. Therefore, effective inhibition of the accumulation of pathogenic proteins has become a priority. As the second brain of human, the gut plays an important role in regulate emotion and cognition functions. Recent studies have reported that the disturbance of gut microbiota (GM) is closely related to accumulation of pathogenic proteins in NDs. On the one hand, pathogenic proteins directly produced by GM are transmitted from the gut to the central center via vagus nerve. On the other hand, The harmful substances produced by GM enter the peripheral circulation through intestinal barrier and cause inflammation, or cross the blood-brain barrier into the central center to cause inflammation, and cytokines produced by the central center cause the production of pathogenic proteins. These pathogenic proteins can produced by the above two aspects can cause the activation of central microglia and further lead to NDs development. In addition, certain GM and metabolites have been shown to have neuroprotective effects. Therefore, modulating GM may be a potential clinical therapeutic approach for NDs. In this review, we summarized the possible mechanism of NDs caused by abnormal accumulation of pathogenic proteins mediated by GM to induce the activation of central microglia, cause central inflammation and explore the therapeutic potential of dietary therapy and fecal microbiota transplantation (FMT) in NDs.

Relationships between Inflammation and Age-Related Neurocognitive Changes

The relationship between inflammation and age-related neurocognitive changes is significant, which may relate to the age-related immune dysfunctions characterized by the senescence of immune cells and elevated inflammatory markers in the peripheral circulation and the central nervous system. In this review, we discuss the potential mechanisms, including the development of vascular inflammation, neuroinflammation, organelle dysfunctions, abnormal cholesterol metabolism, and glymphatic dysfunctions as well as the role that the key molecules play in the immune-cognition interplay. We propose potential therapeutic pharmacological and behavioral strategies for ameliorating age-related neurocognitive changes associated with inflammation. Further research to decipher the multidimensional roles of chronic inflammation in normal and pathological aging processes will help unfold the pathophysiological mechanisms underpinning neurocognitive disorders. The insight gained will lay the path for developing cost-effective preventative measures and the buffering or delaying of age-related neurocognitive decline.

Blood-Brain Barrier Dysfunction and Astrocyte Senescence as Reciprocal Drivers of Neuropathology in Aging

As the most abundant cell types in the brain, astrocytes form a tissue-wide signaling network that is responsible for maintaining brain homeostasis and regulating various brain activities. Here, we review some of the essential functions that astrocytes perform in supporting neurons, modulating the immune response, and regulating and maintaining the blood–brain barrier (BBB). Given their importance in brain health, it follows that astrocyte dysfunction has detrimental effects. Indeed, dysfunctional astrocytes are implicated in age-related neuropathology and participate in the onset and progression of neurodegenerative diseases. Here, we review two mechanisms by which astrocytes mediate neuropathology in the aging brain. First, age-associated blood–brain barrier dysfunction (BBBD) causes the hyperactivation of TGFβ signaling in astrocytes, which elicits a pro-inflammatory and epileptogenic phenotype. Over time, BBBD-associated astrocyte dysfunction results in hippocampal and cortical neural hyperexcitability and cognitive deficits. Second, senescent astrocytes accumulate in the brain with age and exhibit a decreased functional capacity and the secretion of senescent-associated secretory phenotype (SASP) factors, which contribute to neuroinflammation and neurotoxicity. Both BBBD and senescence progressively increase during aging and are associated with increased risk of neurodegenerative disease, but the relationship between the two has not yet been established. Thus, we discuss the potential relationship between BBBD, TGFβ hyperactivation, and senescence with respect to astrocytes in the context of aging and disease and identify future areas of investigation in the field.

Alterations in Immune-Related Defensin Alpha 4 (DEFA4) Gene Expression in Health and Disease

Defensin Alpha 4 (DEFA4) is the fourth member of the Alpha Defensins family known as a part of antimicrobial peptides in the innate immune system. DEFA4 has a strong preference to kill Gram-negative bacteria more than Gram-positive bacteria. In addition, DEFA4 exhibits antiviral activity against human immunodeficiency virus type 1 (HIV-1) in vitro. Moreover, DEFA4 can act as an inhibitor of corticosterone production (Corticostatin). On the other hand, alternations in DEFA4 gene expression have been reported in different disorders such as diseases related to inflammation and immunity dysfunction, brain-related disorders, and various cancers. The up-regulation of DEFA4 appears to be involved in the malignant transformation or aggressive form of cancer. Interestingly, the modified version of DEFA4 fragment (1-11) was potent and efficient against antibiotic-resistant bacteria. This review provides a general background abSaudi Arabia out DEFA4 and sheds light on changes in DEFA4 gene expression in different diseases. The paper also discusses other aspects related to DEFA4 as an antimicrobial and antiviral agent. The research was conducted based on available articles obtained from databases starting from 1988 to the present.

The impact of a history of child abuse on cognitive performance: a cross-sectional study in older patients with a depressive, anxiety, or somatic symptom disorder

BACKGROUND

Child abuse is a major global burden with an enduring negative impact on mental and physical health. A history of child abuse is consistently associated with worse cognitive performance among adults; data in older age groups are inconclusive. Since affective symptoms and cognitive functioning are interrelated among older persons, a synergistic effect can be assumed in patients with affective symptoms who also have suffered from child abuse. This study examines the association between a history of child abuse and cognitive performance in such patients.

METHODS

Cross-sectional data were collected from the 'Routine Outcome Monitoring for Geriatric Psychiatry & Science' project, including 179 older adults (age 60-88 years) with either a unipolar depressive, any anxiety, or somatic symptom disorder referred to specialized geriatric mental health care. A history of physical, sexual, and psychological abuse, and emotional neglect was assessed with a structured interview. Cognitive functioning was measured with three paper and pencils tests (10-words verbal memory test, Stroop Colour-Word test, Digit Span) and four tests from the computerized Cogstate Test Battery (Detection Test, Identification Test, One Card Learning Test, One Back Test). The association between a history of child abuse and cognitive performance was examined by multiple linear regression analyses adjusted for covariates.

RESULTS

Principal component analyses of nine cognitive parameters revealed four cognitive domains, i.e., visual-verbal memory, psychomotor speed, working memory and interference control. A history of child abuse was not associated with any of these cognitive domains. However, when looking at the specific types of child abuse separately, a history of physical abuse and emotional neglect were associated with poorer interference control. A history of physical abuse was additionally associated with better visual-verbal memory.

CONCLUSIONS

The association between a history of child abuse and cognitive performance differs between the different types of abuse. A history of physical abuse might particularly be a key determinant of cognitive performance in older adults with a depressive, anxiety, or somatic symptom disorder. Future studies on the impact of these disorders on the onset of dementia should take child abuse into account.

TRIAL REGISTRATION

ROM-GPS is registered at the Dutch Trial Register ( NL6704 at www.trialregister.nl ).

Blood-Based Biomarkers for Alzheimer's Disease Diagnosis and Progression: An Overview

Alzheimer’s Disease (AD) is a progressive neurodegenerative disease characterized by amyloid-β (Aβ) plaque deposition and neurofibrillary tangle accumulation in the brain. Although several studies have been conducted to unravel the complex and interconnected pathophysiology of AD, clinical trial failure rates have been high, and no disease-modifying therapies are presently available. Fluid biomarker discovery for AD is a rapidly expanding field of research aimed at anticipating disease diagnosis and following disease progression over time. Currently, Aβ_1–42, phosphorylated tau, and total tau levels in the cerebrospinal fluid are the best-studied fluid biomarkers for AD, but the need for novel, cheap, less-invasive, easily detectable, and more-accessible markers has recently led to the search for new blood-based molecules. However, despite considerable research activity, a comprehensive and up-to-date overview of the main blood-based biomarker candidates is still lacking. In this narrative review, we discuss the role of proteins, lipids, metabolites, oxidative-stress-related molecules, and cytokines as possible disease biomarkers. Furthermore, we highlight the potential of the emerging miRNAs and long non-coding RNAs (lncRNAs) as diagnostic tools, and we briefly present the role of vitamins and gut-microbiome-related molecules as novel candidates for AD detection and monitoring, thus offering new insights into the diagnosis and progression of this devastating disease.

Social Justice and Equity: Why Older Adults With Cancer Belong-A Life Course Perspective

The population of older adults with cancer in the United States is rapidly increasing, which will have a substantial impact on the oncology and public health workforces across the cancer continuum, from prevention to end of life. Unfortunately, inequities in existing social structures that cause increased psychosocial stressors have led to disparities in the incidence of cancer and the morbidity and mortality of cancer for individuals from marginalized backgrounds. It is imperative that older adults, especially those from historically marginalized backgrounds, be adequately represented in all stages of cancer research to address health inequities. Continued efforts and progress toward achieving social justice and health equity require a deeper commitment to and better understanding of the impact of social determinants of health within the cancer domain. Undoubtedly, a more holistic and integrated view that extends beyond the biologic and genetic factors of health must be adopted for health entities to recognize the critical role of environmental, behavioral, and social determinants in cancer health disparities. Against this backdrop, this paper uses a life course approach to present a multifactorial framework for understanding and addressing cancer disparities in an effort to advance social justice and health equity for racially and ethnically diverse older adults.

Probiotics: The Next Dietary Strategy against Brain Aging

Owing to their long history of safe use, probiotic microorganisms, typically from the genus Lactobacillus, have long been recognized, especially in traditional and fermented food industries. Although conventionally used for dairy, meat, and vegetable fermentation, the use of probiotics in health foods, supplements, and nutraceuticals has gradually increased. Over the past two decades, the importance of probiotics in improving gut health and immunity as well as alleviating metabolic diseases has been recognized. The new concept of a gut-heart-brain axis has led to the development of various innovations and strategies related to the introduction of probiotics in food and diet. Probiotics influence gut microbiota profiles, inflammation, and disorders and directly impact brain neurotransmitter pathways. As brain health often declines with age, the concept of probiotics being beneficial for the aging brain has also gained much momentum and emphasis in both research and product development. In this review, the concept of the aging brain, different in vivo aging models, and various aging-related benefits of probiotics are discussed.

Exercise duration differentially effects age-related neuroinflammation and hippocampal neurogenesis

The physiological effects of exercise vary as a function of frequency and length. However, research on the duration-dependent effects of exercise has focused primarily on young adults and less is known about the influence of exercise duration in the aged. The current study compared the effects of short-term and long-term running wheel access on hippocampal neurogenesis and neuroimmune markers in aged (19-23 months) male C57BL/6J mice. Aged mice were given 24-hour access to a running wheel for 14 days (short-term) or 51 days (long-term). Groups of non-running aged and young (5 months) mice served as comparison groups to detect age-related differences and effects of exercise. Long-term, but not short-term, exercise increased hippocampal neurogenesis as assessed by number of doublecortin (DCX) positive cells in the granular cell layer. Assessment of cytokines, receptors, and glial-activation markers showed the expected age-related increase compared to young controls. In the aged, exercise as a function of duration regulated select aspects of the neuroimmune profile. For instance, hippocampal expression of interleukin (IL)-10 was increased only following long-term exercise. While in contrast brain levels of IL-6 were reduced by both short- and long-term exercise. Additional findings showed that exercise does not modulate all aspects of age-related neuroinflammation and/or may have differential effects in hippocampal compared to brain samples. Overall, the data indicate that increasing exercise duration produces more robust effects on immune modulation and hippocampal neurogenesis.

Characteristics of Dysregulated Proinflammatory Cytokines and Cognitive Dysfunction in Late-Life Depression and Amnestic Mild Cognitive Impairment

Background

Late-life depression (LLD) and amnestic mild cognitive impairment (aMCI) are two different diseases associated with a high risk of developing Alzheimer's disease (AD). Both diseases are accompanied by dysregulation of inflammation. However, the differences and similarities of peripheral inflammatory parameters in these two diseases are not well understood.

Methods

We used Luminex assays to measure 29 cytokines simultaneously in the plasma of two large cohorts of subjects at high risk for AD (23 LLD and 23 aMCI) and 23 normal controls (NCs) in the community. Demographics and lifestyle factors were also collected. Cognitive function was evaluated with the Chinese versions of the Montreal Cognitive Assessment (C-MoCA) and neuropsychological test battery (NTB).

Results

We observed a remarkably increased level of IL-6 in the plasma and reduced levels of chemokines (CXCL11 and CCL13) in the LLD group compared with the aMCI group. The LLD group also showed lower levels of CXCL16 than the NC group. Furthermore, altered cytokine levels were associated with abnormal results in neuropsychological testing and Geriatric Depression Scale scores in both the LLD and aMCI groups. Notably, combinations of cytokines (IL-6 and CCL13) and two subitems of C-MoCA (orientation and short-term memory) generated the best area under the receiver operating characteristic curve (AUROC = 0.974).

Conclusion

A novel model based on proinflammatory cytokines and brief screening tests performs with fair accuracy in the discrimination between LLD and aMCI. These findings will give clues to provide new therapeutic targets for interventions or markers for two diseases with similar predementia syndromes.

Personality pathology predicts increased informant-reported, but not performance-based, cognitive decline: Findings from two samples

Research on the relationship between normal-range personality and cognitive aging has demonstrated consistent, modest effects. The current investigation increases our understanding of unhealthy cognitive aging by testing whether personality disorders (PDs), specifically borderline, avoidant, and obsessive-compulsive PDs, show prospective associations with the onset of cognitive problems. Interpersonal stressful life events and social support were expected to mediate these relationships. The current investigation used data from 2 longitudinal studies of older adulthood: the Alzheimer's disease Research Center cohort (ADRC, N = 434, Mage = 69.95, 56% women) and the St. Louis Personality and Aging Network study (SPAN, N = 1,058, Mage = 65.92, 54% women). The ADRC study administered a battery of neuropsychological tests to assess cognitive ability/memory. Borderline PD was measured with a composite from the NEO Five-Factor Inventory. The SPAN study administered self-, informant, and interview measures of the three PDs; a free-recall task; and an informant report measure of cognitive problems. Borderline PD features exhibited cross-sectional correlations with memory (ADRC: r = -.11; SPAN: all rs = -.08), general cognitive ability (ADRC: r = -.11), and informant-reported cognitive problems (rs ranged from .15 to .39). Most importantly, borderline PD features predicted an increase in informant-reported cognitive problems in SPAN participants (standardized bs = .13 and .15) over a 2-year period, but they did not predict a deterioration in the performance-based cognitive measures in either study. Avoidant and obsessive-compulsive PDs exhibited little association with cognitive aging. Neither interpersonal variable mediated any of these effects. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Adverse childhood experiences and cognitive function in adulthood: examining the roles of depressive symptoms and inflammation in a prospective cohort study

PURPOSE

Adverse childhood experiences (ACEs) have been associated with cognitive decline in adulthood. However, the underlying mechanisms implicated remain unclear. This study investigated depressive symptoms and systemic inflammation as potential mediators of the association between ACEs and later cognitive function.

METHODS

Participants were adults aged 50 + from the English Longitudinal Study of Ageing (N = 3029; 54.8% female). Measures included self-reported ACEs at wave 3 (2006-2007), C-reactive protein (CRP) and depressive symptoms at wave 4 (2008-2009), and cognitive function at waves 3 and 7 (2014-2015). Mediation analyses examined the direct associations between ACEs and cognitive function at wave 7 and the indirect associations via depressive symptoms and CRP at wave 4. In a first set of analyses, models were adjusted for sociodemographic factors and baseline cognitive function. In a second set of analyses, models were additionally adjusted for BMI and health behaviours (n = 1915).

RESULTS

Cumulative ACEs exposure positively predicted depressive symptoms (b = 0.184, s.e. = 0.034, p < .001), which in turn predicted poorer cognitive function at wave 7 (b =  - 0.035, s.e. = 0.008, p < .001). ACEs also positively predicted systemic inflammation as measured by CRP (b = 0.031, s.e. = 0.01, p = 0.0016). However, CRP did not mediate the association between ACEs and later cognitive function (b =  - 0.0002, 95% CI: - 0.002, 0.002).

CONCLUSION

These findings suggest that ACEs may be related to cognitive decline partly via depressive symptoms and corroborate prior research linking ACEs with systemic inflammation in adulthood.

Inflammatory Blood Biomarker Kynurenine Is Linked With Elevated Neuroinflammation and Neurodegeneration in Older Adults: Evidence From Two 1H-MRS Post-Processing Analysis Methods

RATIONALE AND OBJECTIVES

Pro-inflammatory processes have been argued to play a role in conditions associated with cognitive decline and neurodegeneration, like aging and obesity. Only a limited number of studies have tried to measure both peripheral and central biomarkers of inflammation and examined their interrelationship. The primary aim of this study was to examine the hypothesis that chronic peripheral inflammation would be associated with neurometabolic changes that indicate neuroinflammation (the combined elevation of myoinositol and choline), brain gray matter volume decrease, and lower cognitive functioning in older adults.

MATERIALS AND METHODS

Seventy-four older adults underwent bio-impedance body composition analysis, cognitive testing with the Montreal Cognitive Assessment (MoCA), blood serum analysis of inflammatory markers interleukin-6 (IL-6) and kynurenine, magnetic resonance imaging (MRI), and proton magnetic resonance spectroscopy (¹H-MRS) of the brain. Neurometabolic findings from both Tarquin and LCModel ¹H-MRS post-processing software packages were compared. The regions of interest for MRI and ¹H-MRS measurements were dorsal posterior cingulate cortex (DPCC), left hippocampal cortex (HPC), left medial temporal cortex (MTC), left primary sensorimotor cortex (SM1), and right dorsolateral prefrontal cortex (DLPFC).

RESULTS

Elevated serum kynurenine levels were associated with signs of neuroinflammation, specifically in the DPCC, left SM1 and right DLPFC, and signs of neurodegeneration, specifically in the left HPC, left MTC and left SM1, after adjusting for age, sex and fat percentage (fat%). Elevated serum IL-6 levels were associated with increased Glx levels in left HPC, left MTC, and right DLPFC, after processing the ¹H-MRS data with Tarquin. Overall, the agreement between Tarquin and LCModel results was moderate-to-strong for tNAA, tCho, mIns, and tCr, but weak to very weak for Glx. Peripheral inflammatory markers (IL-6 and kynurenine) were not associated with older age, higher fat%, decreased brain gray matter volume loss or decreased cognitive functioning within a cohort of older adults.

CONCLUSION

Our results suggest that serum kynurenine may be used as a peripheral inflammatory marker that is associated with neuroinflammation and neurodegeneration, although not linked to cognition. Future studies should consider longitudinal analysis to assess the causal inferences between chronic peripheral and neuroinflammation, brain structural and neurometabolic changes, and cognitive decline in aging.

Inflammation mediates depression and generalized anxiety symptoms predicting executive function impairment after 18 years

INTRODUCTION

Scar theories propose that elevated depression and anxiety can predispose people to future decreased executive function (EF) via heightened inflammation across decades. However, more longitudinal (versus cross-sectional) research on this topic is needed.

OBJECTIVE

We thus investigated if increased major depressive disorder (MDD), generalized anxiety disorder (GAD), and panic disorder (PD) severity predicted EF decrement 18 years later via heightened inflammation.

METHOD

Community-dwelling adults participated in this study. Time 1 (T1) MDD, GAD, and PD severity (Composite International Diagnostic Interview-Short Form), T2 inflammation (interleukin-6, C-reactive protein, and fibrinogen blood levels concentration), and T2 and T3 EF (Brief Test of Adult Cognition by Telephone) were measured. The waves of assessment were spaced approximately 9 years apart. Structural equation modeling was conducted.

RESULTS

Higher T1 MDD and GAD (but not PD) severity forecasted elevated T2 inflammation (Cohen's d = 0.116-0.758). Greater T2 inflammation level predicted lower T3 EF following 9 years (d = -0.782--0.636). The T1 MDD-T3 EF and T1 GAD-T3 EF negative associations were mediated by T2 inflammation, and explained 38% and 19% of the relations, respectively. Direct effects of higher T1 GAD and MDD predicting lower T3 EF were also observed (d = -0.585--0.560). Significant effects remained after controlling for socio-demographic, lifestyle, medication use, various illness variables across time, and T2 EF.

CONCLUSIONS

Inflammation may be a mechanism explaining the T1 MDD-T3 EF and T1 GAD-T3 EF relations. Treatments that target inflammation, worry, and/or depression may prevent future EF decline.

Research advances on how metformin improves memory impairment in "chemobrain"

Cognitive impairment caused by chemotherapy, referred to as “chemobrain,” is observed in approximately 70% of cancer survivors. However, it is not completely understood how chemotherapy induces cognitive dysfunction, and clinical treatment strategies for this problem are lacking. Metformin, used as a first-line treatment for type 2 diabetes mellitus, is reported to reduce the effects of chemobrain. Recently, several studies have examined the effect of metformin in rescuing chemobrain. This review discusses recent clinical/preclinical studies that addressed some mechanisms of chemobrain and evaluates the effect of metformin in rescuing chemobrain and its potential mechanisms of action.

Association of Dietary Inflammatory Index (DII) and Depressive Disorders

A lot of evidence shows that inflammation is related to the development of depression. However, the heterogeneity of depression hinders efforts to understand, prevent and treat this disease. The purpose of this comprehensive review is to summarize the links between inflammation and the established core features of depression, which show more homogeneity than the syndrome itself: overreaction to negative information, changes in reward processing, and cognitive control decline, and somatic syndrome. For each core feature, we first briefly outline its relevance to depression and neurobiological basis, and then review the evidence to investigate the potential role of inflammation. We mainly focus on the discovery of the experimental paradigm of exogenous inflammation. We concluded that inflammation may play a role in overreaction to negative information, altered reward responses, and physical symptoms. There is less evidence to support the effect of inflammation on cognitive control by standard neuropsychological measures. Finally, we discussed the implications for future research and recommendations on how to test the role of inflammation in the pathogenesis of heterogeneous mental illness.

Comparison of the effects of open vs. closed skill exercise on the acute and chronic BDNF, IGF-1 and IL-6 response in older healthy adults

BACKGROUND

Accumulating evidence shows that physical exercise has a positive effect on the release of neurotrophic factors and myokines. However, evidence regarding the optimal type of physical exercise for these release is still lacking. The aim of this study was to assess the acute and chronic effects of open-skill exercise (OSE) compared to closed-skill exercise (CSE) on serum and plasma levels of brain derived neurotrophic factor (BDNFS, BDNFP), and serum levels of insulin like growth factor 1 (IGF-1), and interleukin 6 (IL-6) in healthy older adults.

METHODS

To investigate acute effects, thirty-eight participants were randomly assigned to either an intervention (badminton (aOSE) and bicycling (aCSE), n  = 24, 65.83 ± 5.98 years) or control group (reading (CG), n  = 14, 67.07 ± 2.37 years). Blood samples were taken immediately before and 5 min after each condition. During each condition, heart rate was monitored. The mean heart rate of aOSE and aCSE were equivalent (65 ± 5% of heart rate reserve). In a subsequent 12-week training-intervention, twenty-two participants were randomly assigned to either a sport-games (cOSE, n  = 6, 64.50 ± 6.32) or a strength-endurance training (cCSE, n  = 9, 64.89 ± 3.51) group to assess for chronic effects. Training intensity for both groups was adjusted to a subjective perceived exertion using the CR-10 scale (value 7). Blood samples were taken within one day after the training-intervention.

RESULTS

BDNFS, BDNFP, IGF-1, and IL-6 levels increased after a single exercise session of 30 min. After 12 weeks of training BDNFS and IL-6 levels were elevated, whereas IGF-1 levels were reduced in both groups. However, only in the cOSE group these changes were significant. We could not find any significant differences between the exercise types.

CONCLUSION

Our results indicate that both exercise types are efficient to acutely increase BDNFS, BDNFP, IGF-1 and IL-6 serum levels in healthy older adults. Additionally, our results tend to support that OSE is more effective for improving basal BDNFS levels after 12 weeks of training.

Cytomegalovirus Immunity, Inflammation and Cognitive Abilities in the Elderly

Reducing the socioeconomic toll from age-related physical and mental morbidities requires better understanding of factors affecting healthy aging. While many environmental, lifestyle, and genetic factors affect healthy aging, this study addressed the influence of cytomegalovirus (CMV) infection and immunity on age-related inflammation and cognitive abilities. Healthy adults 70–90 years old were recruited into a prospective study investigating relationships between anti-CMV immunity, markers of inflammation, baseline measures of cognitive ability, and changes in cognitive ability over 18 months. Humoral and cellular responses against CMV, levels of inflammatory markers, and cognitive abilities were measured at study entry, with measurement of cognitive abilities repeated 18 months later. CMV-seropositive and -seronegative sub-groups were compared, and relationships between anti-CMV immunity, markers of inflammation, and cognitive ability were assessed. Twenty-eight of 39 participants were CMV-seropositive, and two had CMV-specific CD8⁺ T cell responses indicative of CMV immune memory inflation. No significant differences for markers of inflammation or measures of cognitive ability were observed between groups, and cognitive scores changed little over 18 months. Significant correlations between markers of inflammation and cognitive scores with interconnection between anti-CMV antibody levels, fractalkine, cognitive ability, and depression scores suggest areas of focus for future studies.

Drinking and smoking polygenic risk is associated with childhood and early-adulthood psychiatric and behavioral traits independently of substance use and psychiatric genetic risk

Alcohol drinking and tobacco smoking are hazardous behaviors associated with a wide range of adverse health outcomes. In this study, we explored the association of polygenic risk scores (PRS) related to drinks per week, age of smoking initiation, smoking initiation, cigarettes per day, and smoking cessation with 433 psychiatric and behavioral traits in 4498 children and young adults (aged 8-21) of European ancestry from the Philadelphia neurodevelopmental cohort. After applying a false discovery rate multiple testing correction accounting for the number of PRS and traits tested, we identified 36 associations related to psychotic symptoms, emotion and age recognition social competencies, verbal reasoning, anxiety-related traits, parents' education, and substance use. These associations were independent of the genetic correlations among the alcohol-drinking and tobacco-smoking traits and those with cognitive performance, educational attainment, risk-taking behaviors, and psychopathology. The removal of participants endorsing substance use did not affect the associations of each PRS with psychiatric and behavioral traits identified as significant in the discovery analyses. Gene-ontology enrichment analyses identified several neurobiological processes underlying mechanisms of the PRS associations we report. In conclusion, we provide novel insights into the genetic overlap of smoking and drinking behaviors in children and young adults, highlighting their independence from psychopathology and substance use.

Early life Adversity, functional connectivity and cognitive performance in Schizophrenia: The mediating role of IL-6

OBJECTIVE

Exposure to childhood trauma (CT) is associated with cognitive impairment in schizophrenia, and deficits in social cognition in particular. Here, we sought to test whether IL-6 mediated the association between CT and social cognition both directly, and sequentially via altered default mode network (DMN) connectivity.

METHODS

Three-hundred-and-eleven participants (104 patients and 207 healthy participants) were included, with MRI data acquired in a subset of n = 147. CT was measured using the childhood trauma questionnaire (CTQ). IL-6 was measured in both plasma and in toll like receptor (TLR) stimulated whole blood. The CANTAB emotion recognition task (ERT) was administered to assess social cognition, and cortical connectivity was assessed based on resting DMN connectivity.

RESULTS

Higher IL-6 levels, measured both in plasma and in toll-like receptor (TLR-2) stimulated blood, were significantly correlated with higher CTQ scores and lower cognitive and social cognitive function. Plasma IL-6 was further observed to partly mediate the association between higher CT scores and lower emotion recognition performance (CTQ total: β_indirect -0.0234, 95% CI: -0.0573 to -0.0074; CTQ physical neglect: β_indirect = -0.0316, 95% CI: -0.0741 to -0.0049). Finally, sequential mediation was observed between plasma IL-6 levels and DMN connectivity in mediating the effects of higher CTQ on lower social cognitive function (β_indirect = -0.0618, 95% CI: -0.1523 to -0.285).

CONCLUSION

This work suggests that previous associations between CT and social cognition may be partly mediated via an increased inflammatory response. IL-6's association with changes in DMN activity further suggest at least one cortical network via which CT related effects on cognition may be transmitted.

Inflammatory Potential of Diet Is Associated with Biomarkers Levels of Inflammation and Cognitive Function among Postmenopausal Women

In postmenopausal women (PW), estrogen depletion may predispose to cognitive decline through an increased risk of chronic inflammation. Unhealthy diets also appear to have an impact on the cognitive health of these women. The aim of this study was to investigate the association between inflammatory potential of the diet, levels of inflammatory biomarkers, and cognitive function in PW. In a population of 222 PW, energy intake-adjusted Dietary Inflammatory Index (E-DII) was used to assess the dietary inflammatory potential. Cognitive function was estimated using the Polish version of Mini-Mental State Examination (MMSE), corrected by age and educational level. Selected biochemical inflammatory markers (C-reactive protein, CRP; interleukin-6, IL-6; and tumor necrosis factor alpha, TNF-α) were measured by ELISA tests. PW with an anti-inflammatory diet (first tercile) had significantly higher MMSE, while BMI, percentage fat mass and TNFα concentration were significantly lower compared to those with the most proinflammatory diets (third tercile). Women with cognitive impairment had significantly higher IL-6 concentrations (4.1 (0.8) pg/mL vs. 2.5 (0.2) pg/mL, p = 0.004), and were less educated (12.7 (0.7) years vs. 14.1 (0.2) years, p = 0.03) and less physically active compared to cognitively normal women. PW with the most proinflammatory diets had increased odds of cognitive impairment compared to those with the most anti-inflammatory diets, even after adjustment (OR = 11.10, 95% confidence level; 95%CI: 2.22; 55.56; p = 0.002). Each one-point increase in E-DII (as a continuous value) was also associated with 1.55-times greater odds of cognitive impairment (95%Cl: 1.19; 2.02 p = 0.003) in this population. Dietary inflammation may increase the risk of cognitive impairment in PW, but future studies should include a more sensitive battery of tests to assess cognitive function in this population. Implementation of an anti-inflammatory dietary pattern in PW may help prevent cognitive decline.

Peripheral inflammatory biomarkers predict the deposition and progression of amyloid-β in cognitively unimpaired older adults

INTRODUCTION

Systemic inflammation has been increasingly implicated in the pathogenesis of Alzheimer's disease (AD), yet the mechanistic and temporal specificity of this relationship is poorly understood. We aimed to characterize the cross-sectional and longitudinal associations between peripheral inflammatory biomarkers, cognition, and Aβ deposition in oldest-old cognitively unimpaired (CU) adults.

METHODS

A large sample of 139 CU older adults (mean age (range) = 85.4 (82-95)) underwent neuropsychological testing, Pittsburgh compound-B (PiB)-PET imaging and structural MRI. Hierarchical regression models examined associations between circulating inflammatory biomarkers (Interleukin-6 (IL-6), soluble Tumor Necrosis Factor receptors 1 and 2 (sTNFr1 and sTNFr2), soluble cluster of differentiation 14 (sCD14), C-reactive protein (CRP)), cognition, and global and regional Aβ deposition at baseline and over follow-up. Indices of preclinical disease, including pathologic Aβ status and hippocampal volume, were incorporated to assess conditional associations.

RESULTS

At baseline evaluation, higher concentrations of IL-6 and sTNFr2 were associated with greater global Aβ burden in those with lower hippocampal volume. In longitudinal models, IL-6 predicted subsequent conversion to MCI and both IL-6 and CRP predicted greater change in global and regional Aβ deposition specifically among participants PiB-positive at baseline. These relationships withstood adjustment for demographic factors, anti-hypertensive medication use, history of diabetes, heart disease, APOE ε4 carrier status, and white matter lesions.

DISCUSSION

In a large prospective sample of CU adults aged 80 and over, peripheral inflammatory biomarkers were associated with and predictive of the progression of Aβ deposition. This was specific to those with biomarker evidence of preclinical AD at baseline, supporting recent evidence of disease-state-dependent differences in inflammatory expression profiles. Chronic, low-level systemic inflammation may exacerbate the deposition of Aβ pathology among those with emerging disease processes, and place individuals at a higher risk of developing clinically significant cognitive impairment.

Unravelling the impacts of western-style diets on brain, gut microbiota and cognition

The steady rise in the prevalence of obesity has been fostered by modern environments that reduce energy expenditure and encourage consumption of 'western'-style diets high in fat and sugar. Obesity has been consistently associated with impairments in executive function and episodic memory, while emerging evidence indicates that high-fat, high-sugar diets can impair aspects of cognition within days, even when provided intermittently. Here we review the detrimental effects of diet and obesity on cognition and the role of inflammatory and circulating factors, compromised blood-brain barrier integrity and gut microbiome changes. We next evaluate evidence for changing risk profiles across life stages (adolescence and ageing) and other populations at risk (e.g. through maternal obesity). Finally, interventions to ameliorate diet-induced cognitive deficits are discussed, including dietary shifts, exercise, and the emerging field of microbiome-targeted therapies. With evidence that poor diet and obesity impair cognition via multiple mechanisms across the human lifespan, the challenge for future research is to identify effective interventions, in addition to diet and exercise, to prevent and ameliorate adverse effects.

Role of IL-6 in the regulation of neuronal development, survival and function

The pleiotropic cytokine interleukin-6 (IL-6) is emerging as a molecule with both beneficial and destructive potentials. It can exert opposing actions triggering either neuron survival after injury or causing neurodegeneration and cell death in neurodegenerative or neuropathic disorders. Importantly, neurons respond differently to IL-6 and this critically depends on their environment and whether they are located in the peripheral or the central nervous system. In addition to its hub regulator role in inflammation, IL-6 is recently emerging as an important regulator of neuron function in health and disease, offering exciting possibilities for more mechanistic insight into the pathogenesis of mental, neurodegenerative and pain disorders and for developing novel therapies for diseases with neuroimmune and neurogenic pathogenic components.

Better Identification of Cognitive Decline With Interleukin-2 Than With Amyloid and Tau Protein Biomarkers in Amnestic Mild Cognitive Impairment

The rate of cognitive decline among patients with amnestic mild cognitive impairment (aMCI) varies, and it is thus crucial to accurately predict the probability of cognitive deterioration in patients with MCI. We compared the potential of cytokines with amyloid beta (Aβ) and tau biomarkers for predicting cognitive decline in patients with aMCI or Alzheimer’s disease (AD). All participants (controls, aMCI, and AD patients) underwent plasma biomarker examinations for Aβ_1–40, Aβ_1–42, total tau (t-tau), tau phosphorylated at threonine 181 [p-Tau181]), and 29 cytokines and baseline cognitive tests, including Mini-Mental State Examination (MMSE). The correlation between biomarker levels and annual MMSE change during the follow-up was examined. Receiver operating characteristic (ROC) curve analysis was performed to determine whether the statistically significant plasma biomarkers could identify cognitive decline. Higher baseline levels of IL-2, sCD40L, IL-8, and VEGF were associated with a lower annual cognitive decline in the aMCI group, and higher baseline levels of Aβ_1–40, IFNγ, IL-5, IL-17A, IL-25, and FGF were associated with a rapid annual cognitive decline in the AD group. IL-2 had a high discriminatory capacity for identifying cognitive decline, with an area under curve (AUC) of 85.7% in the aMCI group, and the AUC was slightly increased when combining IL-2 with Aβ or tau biomarkers. However, none of the biomarkers had a satisfactory discriminatory capacity in the AD group. IL-2 may have a better discriminatory capacity for identifying cognitive decline than Aβ and tau biomarkers in patients with aMCI.

Sleep, inflammation and cognitive function in middle-aged and older adults: A population-based study

BACKGROUND

Sleep plays a key role in preserving cognitive function. However, the optimal strategies of sleep for cognition and the underlying mechanism are not well-established.

METHODS

A cross-sectional study was performed using the China Health and Retirement Longitudinal Study (CHARLS), 2011-2012 survey. Self-reported nighttime sleep and afternoon napping data were collected. Fasting blood collected was analyzed for the high-sensitivity C-reactive protein (CRP) and white blood cell.

RESULTS

Both nighttime sleep and afternoon napping were significantly associated with cognition after adjusting for confounders (p < 0.05). Precisely, participants with nighttime sleep of 6.1-7h had the highest cognition scores (p < 0.05). Participants with less than 30 min afternoon napping had the highest cognition scores (p < 0.05). The synergistic effect of nighttime sleep and afternoon napping was not significant (p > 0.05). Nighttime sleep and afternoon napping were significantly related to the white blood cell, but not the high-sensitivity CRP. The white blood cell mediated the association between sleep and cognition (p < 0.05).

CONCLUSION

Nighttime sleep of six to seven hours and afternoon napping of less than 30 minutes are associated with optimal cognitive function in middle-aged and older people, respectively. Sleep influences cognition partly via the inflammatory profile.