Post-Stroke Social Isolation Reduces Cell Proliferation in the Dentate Gyrus and Alters miRNA Profiles in the Aged Female Mice Brain

Factors associated with social isolation in stroke patients: a systematic review and meta-analysis

OBJECTIVE

Systematic evaluation of factors influencing social isolation in stroke patients for further intervention studies.

METHODS

We searched for observational studies in 7 databases from inception to January 2024. Two researchers performed literature screening, quality assessment, and data extraction independently according to inclusion and exclusion criteria, and meta-analysis was performed using R4.3.1 software.

RESULTS

A total of 10 studies with a total sample size of 4162 cases were included. Meta-analysis showed that social isolation in stroke patients was associated with economic status (β'=-0.21, 95%CI:0.39, -0.02; P=0.0261), degree of education (β'=-0.16, 95%CI:0.29, -0.03; P=0.0171), marital status (β'=0.13, 95%CI:0.04, 0.23; P=0.0069), social support (β'=-0.37, 95%CI;-0.50, -0.25; P<0.0001), stigma(β'=0.48, 95%CI:0.25, 0.72; P<0.0001), symptom burden (β'=0.25, 95%CI:0.18, 0.31; P<0.0001), course of disease (β'=0.23, 95%CI:0.08, 0.37; P=0.0021), combined chronic diseases (β'=0.14, 95%CI:0.04, 0.24; P=0.0057), and limb function (β'=0.33, 95%CI:0.23, 0.43; P<0.0001) were associated. Meta-regression and subgroup analyses showed that disease stage and sample source were sources of heterogeneity.

CONCLUSION

There are many factors influencing the social isolation of stroke patients, and healthcare professionals should take timely and targeted measures to prevent and intervene effectively, with a view to improving the social participation of stroke patients and reducing their social isolation.

Physical and social environmental enrichment alleviate ferroptosis and inflammation with inhibition of TLR4/MyD88/p38MAPK pathway in chronic cerebral hypoperfusion rats

A typical enriched environment (EE), which combines physical activity and social interaction, has been proven to mitigate cognitive impairment caused by chronic cerebral hypoperfusion (CCH). However, it remains unclear how the different components of EE promote cognitive recovery after CCH. This study stripped out the different components of EE into physical environmental enrichment (PE) and social environmental enrichment (SE), and compared the neuroprotective effects of PE, SE and typical EE (PSE) in CCH. The results of novel object recognition and Morris water maze tests showed that PE, SE, and PSE improved cognitive function in CCH rats. Additionally, Nissl and TUNEL staining revealed that three EEs reduced neuronal loss in the hippocampus. PSE exhibited superior neuroprotective and functional improvement effects compared to PE and SE, while there was no significant difference between PE and SE. Furthermore, three EEs reduced lipid peroxidation in the hippocampus with decreasing the levels of MDA and increasing the activities of SOD and GSH. The expression of SLC7A11 and GPX4 was increased, while the level of p53 was reduced in three EEs. This suggested that three EEs inhibited ferroptosis by maintaining the redox homeostasis in the hippocampus. Three EEs reduced the levels of IL-β, TNF-α, and IL-6, thereby inhibiting neuroinflammation. Additionally, Western blotting and immunofluorescence results indicated that three EEs also inhibited the TLR4/MyD88/p38MAPK signaling pathway. These findings collectively demonstrated that the three EEs alleviated hippocampal ferroptosis and neuroinflammation in CCH rats, thereby reducing neuronal loss, which might be associated with the inhibition of the TLR4/MyD88/p38MAPK signaling pathway. Moreover, the study results supported that it is only through the combination of physical exercise and social interaction that the optimal neuroprotective effects can be achieved. These findings provided valuable insights for the prevention and treatment of vascular cognitive impairment.

Poststroke Depression: An Update

The presence of neuropsychiatric disorders after stroke has been recognized for more than 100 years, but controlled systematic studies did not begin until the 1970s. The most clinically important advances, however, have been in the treatment and prevention of poststroke depression (PSD). Recent meta-analyses of randomized controlled trials (RCTs) for the treatment of PSD have demonstrated the efficacy of antidepressants. Similarly, RCTs for the prevention of PSD have shown that antidepressants significantly decrease the incidence of PSD compared with placebo. Early treatment of PSD with antidepressants also appears to enhance both physical and cognitive recovery from stroke and may increase survival up to 10 years. Genetic and epigenetic variations, white matter disease, cerebrovascular deregulation, altered neuroplasticity, and changes in glutamate neurotransmission may be relevant etiological factors.

Reversal of the detrimental effects of social isolation on ischemic cerebral injury and stroke-associated pneumonia by inhibiting small intestinal T-cell migration into the brain and lung

Social isolation (ISO) is associated with an increased risk and poor outcomes of ischemic stroke. However, the roles and mechanisms of ISO in stroke-associated pneumonia (SAP) remain unclear. Adult male mice were single- or pair-housed with an ovariectomized female mouse and then subjected to transient middle cerebral artery occlusion. Isolated mice were treated with the natriuretic peptide receptor A antagonist A71915 or anti-gamma-delta (γδ) TCR monoclonal antibody, whereas pair-housed mice were treated with recombinant human atrial natriuretic peptide (rhANP). Subdiaphragmatic vagotomy (SDV) was performed 14 days before single- or pair-housed conditions. We found that ISO significantly worsened brain and lung injuries relative to pair housing, which was partially mediated by elevated interleukin (IL)-17A levels and the migration of small intestine-derived inflammatory γδ T-cells into the brain and lung. However, rhANP treatment or SDV could ameliorate ISO-exacerbated post-stroke brain and lung damage by reducing IL-17A levels and inhibiting the migration of inflammatory γδ T-cells into the brain and lung. Our results suggest that rhANP mitigated ISO-induced exacerbation of SAP and ischemic cerebral injury by inhibiting small intestine-derived γδ T-cell migration into the lung and brain, which could be mediated by the subdiaphragmatic vagus nerve.

Effects of Objective and Perceived Social Isolation on Cardiovascular and Brain Health: A Scientific Statement From the American Heart Association

Background Social isolation, the relative absence of or infrequency of contact with different types of social relationships, and loneliness (perceived isolation) are associated with adverse health outcomes. Objective To review observational and intervention research that examines the impact of social isolation and loneliness on cardiovascular and brain health and discuss proposed mechanisms for observed associations. Methods We conducted a systematic scoping review of available research. We searched 4 databases, PubMed, PsycInfo, Cumulative Index of Nursing and Allied Health, and Scopus. Findings Evidence is most consistent for a direct association between social isolation, loneliness, and coronary heart disease and stroke mortality. However, data on the association between social isolation and loneliness with heart failure, dementia, and cognitive impairment are sparse and less robust. Few studies have empirically tested mediating pathways between social isolation, loneliness, and cardiovascular and brain health outcomes using appropriate methods for explanatory analyses. Notably, the effect estimates are small, and there may be unmeasured confounders of the associations. Research in groups that may be at higher risk or more vulnerable to the effects of social isolation is limited. We did not find any intervention studies that sought to reduce the adverse impact of social isolation or loneliness on cardiovascular or brain health outcomes. Conclusions Social isolation and loneliness are common and appear to be independent risk factors for worse cardiovascular and brain health; however, consistency of the associations varies by outcome. There is a need to develop, implement, and test interventions to improve cardiovascular and brain health for individuals who are socially isolated or lonely.

Dysregulation of Principal Circulating miRNAs in Non-human Primates Following Ischemic Stroke

Despite the recent interest in plasma microRNA (miRNA) biomarkers in acute ischemic stroke patients, there is limited knowledge about the miRNAs directly related to stroke itself due to the multiple complications in patients, which has hindered the research progress of biomarkers and therapeutic targets of ischemic stroke. Therefore, in this study, we compared the differentially expressed miRNA profiles in the plasma of three rhesus monkeys pre- and post-cerebral ischemia. After cerebral ischemia, Rfam sequence category revealed increased ribosomic RNA (rRNA) and decreased transfer RNAs (tRNAs) in plasma. Of the 2049 miRNAs detected after cerebral ischemia, 36 were upregulated, and 76 were downregulated (fold change ≥2.0, P < 0.05). For example, mml-miR-191-5p, miR-421, miR-409-5p, and let-7g-5p were found to be significantly overexpressed, whereas mml-miR-128a-5p_R − 2, miR-431_R − 1, and let-7g-3p_1ss22CT were significantly downregulated. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway analyses revealed that these differentially expressed miRNAs were implicated in the regulation of ubiquitin-mediated proteolysis and signaling pathways in cancer, glioma, chronic myeloid leukemia, and chemokine signaling. miRNA clustering analysis showed that mml-let-7g-5p and let-7g-3p_1ss22CT, which share three target genes [RB1-inducible coiled-coil 1 (RB1CC1), G-protein subunit γ 5 (GNG5), and chemokine (C-X-C motif) receptor 4 (CXCR4)], belong to one cluster, were altered in opposite directions following ischemia. These data suggest that circulating mml-let-7g may serve as a therapeutic target for ischemic stroke.

The Long-Term Public Health Impact of Social Distancing on Brain Health: Topical Review

Social distancing has been a critical public health measure for the COVID-19 pandemic, yet a long history of research strongly suggests that loneliness and social isolation play a major role in several cognitive health issues. What is the true severity and extent of risks involved and what are potential approaches to balance these competing risks? This review aimed to summarize the neurological context of social isolation and loneliness in population health and the long-term effects of social distancing as it relates to neurocognitive aging, health, and Alzheimer's disease and related dementias. The full scope of the underlying causal mechanisms of social isolation and loneliness in humans remains unclear partly because its study is not amenable to randomized controlled trials; however, there are many detailed experimental and observational studies that may provide a hypothesis-generating theoretical framework to better understand the pathophysiology and underlying neurobiology. To address these challenges and inform future studies, we conducted a topical review of extant literature investigating associations of social isolation and loneliness with relevant biological, cognitive, and psychosocial outcomes, and provide recommendations on how to approach the need to fill key knowledge gaps in this important area of research.