The Gut Microbiome, Aging, and Longevity: A Systematic Review

Aging is determined by complex interactions among genetic and environmental factors. Increasing evidence suggests that the gut microbiome lies at the core of many age-associated changes, including immune system dysregulation and susceptibility to diseases. The gut microbiota undergoes extensive changes across the lifespan, and age-related processes may influence the gut microbiota and its related metabolic alterations. The aim of this systematic review was to summarize the current literature on aging-associated alterations in diversity, composition, and functional features of the gut microbiota. We identified 27 empirical human studies of normal and successful aging suitable for inclusion. Alpha diversity of microbial taxa, functional pathways, and metabolites was higher in older adults, particularly among the oldest-old adults, compared to younger individuals. Beta diversity distances significantly differed across various developmental stages and were different even between oldest-old and younger-old adults. Differences in taxonomic composition and functional potential varied across studies, but Akkermansia was most consistently reported to be relatively more abundant with aging, whereas Faecalibacterium, Bacteroidaceae, and Lachnospiraceae were relatively reduced. Older adults have reduced pathways related to carbohydrate metabolism and amino acid synthesis; however, oldest-old adults exhibited functional differences that distinguished their microbiota from that of young-old adults, such as greater potential for short-chain fatty acid production and increased butyrate derivatives. Although a definitive interpretation is limited by the cross-sectional design of published reports, we integrated findings of microbial composition and downstream functional pathways and metabolites, offering possible explanations regarding age-related processes.

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The Association Between Sarcopenia and Postoperative Outcomes Among Older Adults With Hip Fracture: A Systematic Review

Journal of Applied Gerontology ◽

10.1177/07334648211006519 ◽

2021 ◽

pp. 073346482110065

Author(s):

Ming-Hsiu Chiang ◽

Yi-Jie Kuo ◽

Yu-Pin Chen

Keyword(s):

Systematic Review ◽

Older Adults ◽

Hip Fracture ◽

Postoperative Mortality ◽

Clinical Event ◽

High Morbidity ◽

Adverse Health Outcomes ◽

Age Related ◽

Study Selection ◽

And Function

Hip fracture is a serious clinical event with high morbidity and mortality. Sarcopenia is characterized by age-related loss of muscle mass and function, leading to several adverse health outcomes. In this systematic review, no limitation criteria were used for study selection and 327 studies were identified in the initial search. Of these, 11 studies comprising a total of 2,314 patients were selected. The overall proportion of older adults with hip fracture having sarcopenia was 44%, with a disparity of approximately 10% between men and women. Most studies have indicated that older adults with sarcopenia had poorer postoperative functional recovery than those without sarcopenia; the association between sarcopenia and high postoperative mortality or long hospital stay was heterogeneous. Well-organized studies with longer follow-up periods are warranted.

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Distinct composition and metabolic functions of human gut microbiota are associated with cachexia in lung cancer patients

The ISME Journal ◽

10.1038/s41396-021-00998-8 ◽

2021 ◽

Author(s):

Yueqiong Ni ◽

Zoltan Lohinai ◽

Yoshitaro Heshiki ◽

Balazs Dome ◽

Judit Moldvay ◽

...

Keyword(s):

Lung Cancer ◽

Gut Microbiota ◽

Cancer Patients ◽

Gut Microbiome ◽

Human Gut ◽

Microbial Composition ◽

Shotgun Metagenomics ◽

Lung Cancer Patients ◽

Microbial Species ◽

Functional Pathways

AbstractCachexia is associated with decreased survival in cancer patients and has a prevalence of up to 80%. The etiology of cachexia is poorly understood, and limited treatment options exist. Here, we investigated the role of the human gut microbiome in cachexia by integrating shotgun metagenomics and plasma metabolomics of 31 lung cancer patients. The cachexia group showed significant differences in the gut microbial composition, functional pathways of the metagenome, and the related plasma metabolites compared to non-cachectic patients. Branched-chain amino acids (BCAAs), methylhistamine, and vitamins were significantly depleted in the plasma of cachexia patients, which was also reflected in the depletion of relevant gut microbiota functional pathways. The enrichment of BCAAs and 3-oxocholic acid in non-cachectic patients were positively correlated with gut microbial species Prevotella copri and Lactobacillus gasseri, respectively. Furthermore, the gut microbiota capacity for lipopolysaccharides biosynthesis was significantly enriched in cachectic patients. The involvement of the gut microbiome in cachexia was further observed in a high-performance machine learning model using solely gut microbial features. Our study demonstrates the links between cachectic host metabolism and specific gut microbial species and functions in a clinical setting, suggesting that the gut microbiota could have an influence on cachexia with possible therapeutic applications.

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The Gut Microbiota and Healthy Aging: A Mini-Review

Gerontology ◽

10.1159/000490615 ◽

2018 ◽

Vol 64 (6) ◽

pp. 513-520 ◽

Cited By ~ 59

Author(s):

Sangkyu Kim ◽

S. Michal Jazwinski

Keyword(s):

Gut Microbiota ◽

Individual Variation ◽

Gut Microbiome ◽

Chronological Age ◽

Low Grade ◽

Beneficial Effects ◽

Gut Dysbiosis ◽

Age Related ◽

Host Health ◽

Nutrient Signaling

The gut microbiota shows a wide inter-individual variation, but its within-individual variation is relatively stable over time. A functional core microbiome, provided by abundant bacterial taxa, seems to be common to various human hosts regardless of their gender, geographic location, and age. With advancing chronological age, the gut microbiota becomes more diverse and variable. However, when measures of biological age are used with adjustment for chronological age, overall richness decreases, while a certain group of bacteria associated with frailty increases. This highlights the importance of considering biological or functional measures of aging. Studies using model organisms indicate that age-related gut dysbiosis may contribute to unhealthy aging and reduced longevity. The gut microbiome depends on the host nutrient signaling pathways for its beneficial effects on host health and lifespan, and gut dysbiosis disrupting the interdependence may diminish the beneficial effects or even have reverse effects. Gut dysbiosis can trigger the innate immune response and chronic low-grade inflammation, leading to many age-related degenerative pathologies and unhealthy aging. The gut microbiota communicates with the host through various biomolecules, nutrient signaling-independent pathways, and epigenetic mechanisms. Disturbance of these communications by age-related gut dysbiosis can affect the host health and lifespan. This may explain the impact of the gut microbiome on health and aging.

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AGE-BASED STEREOTYPE THREAT: A SYSTEMATIC REVIEW OF PRIMING TECHNIQUES AND THEIR EFFECTS

Innovation in Aging ◽

10.1093/geroni/igz038.1705 ◽

2019 ◽

Vol 3 (Supplement_1) ◽

pp. S455-S456

Author(s):

Francesco Vailati Riboni ◽

Francesco Pagnini

Keyword(s):

Systematic Review ◽

Older Adults ◽

Stereotype Threat ◽

Functional Performance ◽

Later Life ◽

Experimental Methods ◽

Experimental Manipulation ◽

Older Individuals ◽

Negative Stereotypes ◽

Age Related

Abstract Age-based stereotype threat (ABST) occurs when older adults are influenced by negative stereotypes about age-related decline and functional losses and ironically behave in disengaging and self-defeating ways that confirm the stereotype (Steele & Aronson, 1995). Aging stereotypes are found to be strong predictors of health and illness outcomes in later life, and are associated with performance in specific areas, mainly in cognitive and physical domains. The current study reviewed the experimental methods and their reported effects previously published in the literature to determine if there were different ABST methods were associated with different types of age-related outcomes. We conducted a systematic review, screening the scientific literature for papers that included experimental manipulation of age-related stereotypes as an independent variable, focusing on samples of older adults (1113 articles, most published after 2003). Through a classification of the common and distinctive characteristics of the different stereotype manipulation techniques, we were able to identify three specific types of experimental methods: by instruction, tests, and interpersonal exposure. Although the mechanism by which stereotypes are associated with functional outcomes in older adults remains unclear, our review suggests it is possible to experimentally control the activation of the stereotype by manipulating its specific characteristics and the way older participants are exposed to it. Findings also highlight the possibility that specific experimental methods used to induce ABST in older individuals may lead to unique and different consequences on functional performance variation.

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Lower-Limb Factors Associated with Balance and Falls in Older Adults: A Systematic Review and Clinical Synthesis

Journal of the American Podiatric Medical Association ◽

10.7547/19-143 ◽

2019 ◽

Vol 110 (5) ◽

Cited By ~ 1

Author(s):

Christopher Neville ◽

Hung Nguyen ◽

Kim Ross ◽

Mariana Wingood ◽

Elizabeth Walker Peterson ◽

...

Keyword(s):

Systematic Review ◽

Older Adults ◽

Lower Limb ◽

Fall Risk ◽

Community Dwelling ◽

Sufficient Evidence ◽

Cochrane Library ◽

Direct Link ◽

Age Related ◽

Falls In Older Adults

Background Despite sufficient evidence to suggest that lower-limb–related factors may contribute to fall risk in older adults, lower-limb and footwear influences on fall risk have not been systematically summarized for readers and clinicians. The purpose of this study was to systematically review and synethesize the literature related to lower-limb, foot, and footwear factors that may increase the risk of falling among community-dwelling older adults. Methods We searched PubMed, Embase, PsycINFO, CINAHL, Web of Science, Cochrane Library, and AgeLine. To describe the trajectory toward increasing risk of falls, we examined those articles that linked age-related changes in the lower limb or footwear to prospective falls or linked them to evidenced-based fall risk factors, such as gait and balance impairment. Results This systematic review consisted of 81 articles that met the review criteria, and the results reflect a narrative review of the appraised literature for eight pathways of lower-limb–related influences on fall risk in older adults. Six of the eight pathways support a direct link to fall risk. Two other pathways link to the intermediate factors but lack studies that provide evidence of a direct link. Conclusions This review provides strong guidance to advance understanding and assist with managing the link between lower-limb factors and falls in older adults. Due to the lack of literature in specific areas, some recommendations were based on observational studies and should be applied with caution until further research can be completed.

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Advanced Aging Enhances the Positivity Effect in Memory: Due to Cognitive Control or Age-Related Decline in Emotional Processing?

Collabra Psychology ◽

10.1525/collabra.222 ◽

2019 ◽

Vol 5 (1) ◽

Cited By ~ 2

Author(s):

Michiko Sakaki ◽

Jasmine A. L. Raw ◽

Jamie Findlay ◽

Mariel Thottam

Keyword(s):

Older Adults ◽

Cognitive Control ◽

Emotional Processing ◽

Aging Brain ◽

Control Mechanisms ◽

Younger Adults ◽

Positivity Effect ◽

Old Adults ◽

Age Related ◽

Conditioned Responses

Older adults typically remember more positive than negative information compared to their younger counterparts; a phenomenon referred to as the ‘positivity effect.’ According to the socioemotional selectivity theory (SST), the positivity effect derives from the age-related motivational shift towards attaining emotionally meaningful goals which become more important as the perception of future time becomes more limited. Cognitive control mechanisms are critical in achieving such goals and therefore SST predicts that the positivity effect is associated with preserved cognitive control mechanisms in older adults. In contrast, the aging-brain model suggests that the positivity effect is driven by an age-related decline in the amygdala which is responsible for emotional processing and emotional learning. The aim of the current research was to address whether the age-related positivity effect is associated with cognitive control or impaired emotional processing associated with aging. We included older old adults, younger old adults and younger adults and tested their memory for emotional stimuli, cognitive control and amygdala-dependent fear conditioned responses. Consistent with prior research, older adults, relative to younger adults, demonstrate better memory for positive over negative images. We further found that within a group of older adults, the positivity effect increases as a function of age, such that older old adults demonstrated a greater positivity effect compared to younger older adults. Furthermore, the positivity effect in older old adults was associated with preserved cognitive control, supporting the prediction of SST. Contrary to the prediction of the aging-brain model, participants across all groups demonstrated similar enhanced skin conductance responses to fear conditioned stimuli – responses known to rely on the amygdala. Our results support SST and suggest that the positivity effect in older adults is achieved by the preserved cognitive control mechanisms and is not a reflection of the impaired emotional function associated with age.

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The Effects of Glucosamine and Chondroitin Sulfate on Gut Microbial Composition: A Systematic Review of Evidence from Animal and Human Studies

Nutrients ◽

10.3390/nu11020294 ◽

2019 ◽

Vol 11 (2) ◽

pp. 294 ◽

Cited By ~ 8

Author(s):

Anna Shmagel ◽

Ryan Demmer ◽

Daniel Knights ◽

Mary Butler ◽

Lisa Langsetmo ◽

...

Keyword(s):

Systematic Review ◽

Gut Microbiota ◽

Chondroitin Sulfate ◽

Gut Microbiome ◽

Human Studies ◽

Journal Articles ◽

Microbial Composition ◽

Microbiome Composition ◽

Search Terms ◽

Quality Evidence

Oral glucosamine sulfate (GS) and chondroitin sulfate (CS), while widely marketed as joint-protective supplements, have limited intestinal absorption and are predominantly utilized by gut microbiota. Hence the effects of these supplements on the gut microbiome are of great interest, and may clarify their mode of action, or explain heterogeneity in therapeutic responses. We conducted a systematic review of animal and human studies reporting the effects of GS or CS on gut microbial composition. We searched MEDLINE, EMBASE, and Scopus databases for journal articles in English from database inception until July 2018, using search terms microbiome, microflora, intestinal microbiota/flora, gut microbiota/flora and glucosamine or chondroitin. Eight original articles reported the effects of GS or CS on microbiome composition in adult humans (four articles) or animals (four articles). Studies varied significantly in design, supplementation protocols, and microbiome assessment methods. There was moderate-quality evidence for an association between CS exposure and increased abundance of genus Bacteroides in the murine and human gut, and low-quality evidence for an association between CS exposure and an increase in Desulfovibrio piger species, an increase in Bacteroidales S24-7 family, and a decrease in Lactobacillus. We discuss the possible metabolic implications of these changes for the host. For GS, evidence of effects on gut microbiome was limited to one low-quality study. This review highlights the importance of considering the potential influence of oral CS supplements on gut microbiota when evaluating their effects and safety for the host.

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Estimation of Cognitive Plasticity in Old Adults Using Dynamic Assessment Techniques

Journal of Cognitive Education and Psychology ◽

10.1891/1945-8959.8.1.38 ◽

2009 ◽

Vol 8 (1) ◽

pp. 38-51 ◽

Cited By ~ 10

Author(s):

Elena Navarro ◽

María Dolores Calero

Keyword(s):

Older Adults ◽

Cognitive Functioning ◽

Dynamic Assessment ◽

Cognitive Status ◽

Diagnostic Utility ◽

Old Adults ◽

Age Related ◽

Assessment Techniques ◽

Cognitive Plasticity

In recent years, research has provided extensive data concerning the use, utility, and appropriateness of dynamic assessment techniques as a way of determining cognitive plasticity in old adults. Current research in this area is focused on three principle lines of investigation: (a) determining neurological correlates of cognitive plasticity evaluated through dynamic assessment techniques; (b) establishing the diagnostic utility of such procedures; and (c) analyzing age-related limits with regard to quantity and domains of plasticity. In this context, the present study was undertaken using a sample of 274 older adults, who were evaluated through two dynamic assessment techniques and one cognitive functioning screening test over a period of 3 consecutive years. Results show differences in plasticity related to both age and cognitive status. The study also demonstrates the capacity of plasticity to predict maintenance and decline in a follow-up period of 3 years.

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Examining Positivity Effect and Working Memory in Young-Old and Very Old Adults Using EEG-Derived Cognitive State Metrics

Research on Aging ◽

10.1177/0164027519865310 ◽

2019 ◽

Vol 41 (10) ◽

pp. 1014-1035

Author(s):

Joelle C. Ruthig ◽

Dmitri P. Poltavski ◽

Thomas Petros

Keyword(s):

Older Adults ◽

Working Memory ◽

Memory Task ◽

Cognitive State ◽

Emotional Stimuli ◽

Very Old ◽

Positivity Effect ◽

Old Adults ◽

Age Related ◽

Young Old

The positivity effect among older adults is a tendency to process more positive and/or less negative emotional stimuli compared to younger adults, with unknown upper age boundaries. Cognitive and emotional working memory were assessed in young-old adults (60–75) and very old adults (VOAs; 80+) to determine whether emotional working memory declines similar to the age-related decline of cognitive working memory. The moderating role of valence on the link between age and emotional working memory was examined to identify change in positivity effect with advanced age. Electroencephalography (EEG) markers of cognitive workload and engagement were obtained to test the theory of cognitive resource allocation in older adults’ emotional stimuli processing. EEG recordings were collected during cognitive memory task and emotional working memory tasks that required rating emotional intensity of images pairs. Results indicate a positivity effect among VOAs that does not require additional cognitive effort and is not likely to diminish with age.

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Effect of Sleep Quality on the Prevalence of Sarcopenia in Older Adults: A Systematic Review with Meta-Analysis

Journal of Clinical Medicine ◽

10.3390/jcm8122156 ◽

2019 ◽

Vol 8 (12) ◽

pp. 2156 ◽

Cited By ~ 5

Author(s):

Jacobo Á. Rubio-Arias ◽

Raquel Rodríguez-Fernández ◽

Luis Andreu ◽

Luis M. Martínez-Aranda ◽

Alejandro Martínez-Rodriguez ◽

...

Keyword(s):

Systematic Review ◽

Older Adults ◽

Sleep Quality ◽

Sleep Duration ◽

Meta Analysis ◽

Cochrane Library ◽

Short Sleep Duration ◽

Related Condition ◽

Age Related ◽

Inadequate Sleep

Sarcopenia is an age-related condition. However, the prevalence of sarcopenia may increase due to a range of other factors, such as sleep quality/duration. Therefore, the aim of the study is to conduct a systematic review with meta-analysis to determine the prevalence of sarcopenia in older adults based on their self-reported sleep duration. Methods: Three electronic databases were used—PubMed-Medline, Web of Science, and Cochrane Library. We included studies that measured the prevalence of sarcopenia, divided according to sleep quality and excluded studies (a) involving populations with neuromuscular pathologies, (b) not showing prevalence values (cases/control) on sarcopenia, and (c) not including classificatory models to determine sleep quality. Results: high prevalence values in older adults with both long and short sleep duration were shown. However, prevalence values were higher in those with inadequate sleep (<6–8 h or low efficiency) (OR 0.76; 95% CI (0.70–0.83); Q = 1.446; p = 0.695; test for overall effect, Z = 6.01, p < 0.00001). Likewise, higher prevalence levels were shown in men (OR 1.61; 95% CI (0.82–3.16); Q = 11.80; p = 0.0189) compared to women (OR 0.77; 95% CI (0.29–2.03); Q = 21.35; p = 0.0003). Therefore, the prevalence of sarcopenia appears to be associated with sleep quality, with higher prevalence values in older adults who have inadequate sleep.

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