Hippocampus Mediates the Effect of Emotional Support on Cognitive Function in Older Adults

Salidroside improves cognitive function in Parkinson's disease via Braf-mediated mitogen‑activated protein kinase signaling pathway

OBJECTIVE

To delve into the underlying mechanism of Salidroside (Sal) on the improvement of cognitive function in Parkinson's Disease (PD).

METHODS

The experimental mice were divided into Control group, Model group [injected with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)], and Model+Sal (low concentration, high concentration) group. Mouse hippocampal tissues were extracted for RNA sequencing to obtain the core pathway and core gene. Mouse plasma was prepared and analyzed by LC-MS to obtain differential metabolites. In vitro experiments were verified by immunofluorescence and lentiviral transduction.

RESULTS

ELISA signaled that Sal facilitated the reduction of neuronal damage and inflammatory reaction in mice. MPTP_Sal_Low and MPTP_Sal_High groups had high levels of glial cell derived neurotrophie factor (GDNF) expression. Differentially expressed genes (DEGs) in control group, MPTP group and MPTP_Sal_High group were identified by transcriptomic, which were classified to the mitogen-activated protein kinase (MAPK) signaling pathway, and the core gene Braf was obtained. Metabolomics manifested that the differential metabolites involved DL-tyrosine, adenosine, phosphoenolpyruvate, and L-tryptophan. In vitro experiments verified that Sal treatment inhibited the up-regulation of p-p38, p-c-Jun N-terminal kinase (JNK), and p-extracellular signal-regulated kinase (ERK) expression, and growth of neuronal protrusions. The OE-Braf group showed a significant up-regulation of the GDNF expression, a decrease in the expression of p-p38, p-JNK, and p-ERK, and a significant growth of neuronal protrusions.

CONCLUSION

Sal may exert its effects in PD through the Braf-mediated MAPK signaling pathway, which can increase GDNF expression and promote neuronal protrusion growth for the protection of neurological function and the improvement of cognitive function.

Social support and cognitive function in Chinese older adults who experienced depressive symptoms: is there an age difference?

Objective

This study examined the moderating effect of overall social support and the different types of social support on cognitive functioning in depressed older adults. We also investigated whether the moderating effect varied according to age.

Methods

A total of 2,500 older adults (≥60 years old) from Shanghai, China were enrolled using a multistage cluster sampling method. Weighted linear regression and multiple linear regression was utilized to analyze the moderating effect of social support on the relationship between depressive symptoms and cognitive function and to explore its differences in those aged 60-69, 70-79, and 80 years and above.

Results

After adjusting for covariates, the results indicated that overall social support (β = 0.091, p = 0.043) and support utilization (β = 0.213, p < 0.001) moderated the relationship between depressive symptoms and cognitive function. Support utilization reduced the possibility of the cognitive decline in depressed older adults aged 60-69 years (β = 0.310, p  < 0.001) and 80 years and above (β = 0.199, p  < 0.001), while objective support increased the possibility of cognitive decline in depressed older people aged 70-79 years (β = -0.189, p  < 0.001).

Conclusion

Our findings highlight the buffering effects of support utilization on cognitive decline in depressed older adults. We suggest that age-specific measures should be taken when providing social support to depressed older adults in order to reduce the deterioration of cognitive function.

Subtypes of social support availability are not differentially associated with memory: a cross-sectional analysis of the Comprehensive Cohort of the Canadian Longitudinal Study on Aging

 This study investigated the association between subtypes of social support availability (SSA) and memory in persons aged 45 to 85 years (n = 24,719). We examined two memory outcomes using a modified Rey Auditory Verbal Learning Test (RAVLT)-immediate recall (RAVLT I) and delayed recall (RAVLT II)-and five subtypes of SSA: affectionate, emotional/informational, positive interactions, tangible, overall. We found statistically significant and adjusted positive associations between all SSA subtypes and memory, except for positive interactions and delayed recall memory. For RAVLT I, the regression coefficients (βˆs) ranged from 0.03 to 0.07; the βˆs for RAVLT II ranged from 0.02 to 0.05. The differences in βˆs for each SSA subtype (βˆ _{RAVLT I} - βˆ _{RAVLT II}) ranged from 0.00 to 0.02 (mean difference = 0.01; 95% confidence interval = -0.01 to 0.03). All effect sizes, regardless of SSA subtype or memory outcome, were small and clinically unimportant.

Psychosocial factors and hippocampal subfields: The Medea-7T study

Specific subfields within the hippocampus have shown vulnerability to chronic stress, highlighting the importance of looking regionally within the hippocampus to understand the role of psychosocial factors in the development of neurodegenerative diseases. A systematic review on psychosocial factors and hippocampal subfield volumes was performed and showed inconsistent results, highlighting the need for future studies to explore this relationship. The current study aimed to explore the association of psychosocial factors with hippocampal (subfield) volumes, using high-field 7T MRI. Data were from the Memory Depression and Aging (Medea)-7T study, which included 333 participants without dementia. Hippocampal subfields were automatically segmented from T2-weighted images using ASHS software. Generalized linear models accounting for correlated outcomes were used to assess the association between subfields (i.e., entorhinal cortex, subiculum, Cornu Ammonis [CA]1, CA2, CA3, dentate gyrus, and tail) and each psychosocial factor (i.e., depressive symptoms, anxiety symptoms, childhood maltreatment, recent stressful life events, and social support), adjusted for age, sex, and intracranial volume. Neither depression nor anxiety was associated with specific hippocampal (subfield) volumes. A trend for lower total hippocampal volume was found in those reporting childhood maltreatment, and a trend for higher total hippocampal volume was found in those who experienced a recent stressful life event. Among subfields, low social support was associated with lower volume in the CA3 (B = -0.43, 95% CI: -0.72; -0.15). This study suggests possible differential effects among hippocampal (subfield) volumes and psychosocial factors.

Assessing the role of depressive symptoms in the association between social engagement and cognitive functioning among older adults: analysis of cross-sectional data from the Longitudinal Aging Study in India (LASI)

OBJECTIVE

The present study aimed to examine the confounding effects of depressive symptoms and the role of gender in the association between social engagement and cognitive functioning among older Indian adults.

DESIGN

Large-scale cross-sectional survey data were analysed.

SETTING AND PARTICIPANTS

Data from the Longitudinal Aging Study in India (2017-2019) were used in the analysis. The sample included 23 584 individuals aged 60 years and above (11 403 men and 12 181 women).

OUTCOME MEASURES

The outcome variable was cognitive functioning, which was based on various measures including immediate and delayed word recall, orientation, executive functioning, arithmetic ability and object naming. Social engagement measure consists of marital status, living arrangement, availability of confidant, and participation in indoor games, and social and cultural functions. The Center for Epidemiological Studies-Depression Scale was used to assess depressive symptoms.

RESULTS

Significant gender differences in mean cognition scores (men: 25.8, women: 21.1; on a scale of 0-43) were observed. Two-way stratification between social engagement and depressive symptoms was significantly associated with cognitive functioning after controlling for selected explanatory factors. Older men with a low level of social engagements had significantly poor cognitive functioning (β=-1.12; 95% CI: -1.53 to -0.72) compared with men with a high level of social engagements. On the other hand, women with a higher level of social engagement performed poorly on cognitive tests (β=-1.54; 95% CI: -2.11 to -0.98) compared with men with higher social engagements. Three-way stratification between social engagement, gender and depressive symptoms suggests that social engagement's buffering effects are lower in women than in men. The Karlson-Holm-Breen method identified a significant confounding effect of depressive symptoms on the relationship between social engagement and cognitive functioning.

CONCLUSION

The positive association of social engagement with cognitive functioning was significantly confounded by depressive symptoms, suggesting the need for maintaining social relations that help improve mental health and cognitive functioning among older adults.

Association of Low Emotional and Tangible Support With Risk of Dementia Among Adults 60 Years and Older in South Korea

IMPORTANCE

The association between social support and dementia risk has been debated. Most previous prospective studies have not differentiated the subtypes of social support.

OBJECTIVE

To examine whether the association between social support and risk of dementia differs by subtype of social support and by sex.

DESIGN, SETTING, AND PARTICIPANTS

This nationwide prospective cohort study included randomly sampled South Korean adults 60 years or older. The study was launched November 1, 2010, with follow-up every 2 years until November 30, 2020. The 5852 participants who completed the assessment for social support and were not diagnosed as having dementia, severe psychiatric disorders including major depressive disorder, or major neurological disorders at the baseline assessment were included in the analysis.

EXPOSURES

Geriatric psychiatrists administered the structured diagnostic interviews and physical examinations to every participant based on the Korean version of the Consortium to Establish a Registry for Alzheimer Disease (CERAD-K) Assessment Packet Clinical Assessment Battery.

MAIN OUTCOMES AND MEASURES

Baseline levels of emotional and tangible support using the Medical Outcomes Survey Social Support Survey.

RESULTS

Among the 5852 participants (mean [SD] age, 69.8 [6.6] years; 3315 women [56.6%]; mean [SD] follow-up duration, 5.9 [2.4] years), 237 (4.0%) had incident all-cause dementia and 160 (2.7%) had incident Alzheimer disease (AD) subtype of dementia. Compared with women who reported having emotional support, those with low emotional support had almost a 2-fold higher incidence of all-cause dementia (18.4 [95% CI, 13.6-23.2] vs 10.7 [95% CI, 9.0-12.5] per 1000 person-years) and AD (14.4 [95% CI, 10.2-18.6] vs 7.8 [95% CI, 6.3-9.3] per 1000 person-years). Adjusted Cox proportional hazard analysis revealed that low emotional support was associated with increased risk of all-cause dementia (hazard ratio, 1.61 [95% CI, 1.10-2.36]; P = .02) and AD (hazard ratio, 1.66 [95% CI, 1.07-2.57]; P = .02) only in women. Low tangible support was not associated with a risk of all-cause dementia or AD regardless of sex.

CONCLUSIONS AND RELEVANCE

The findings of this cohort study suggest that older women with low emotional support constitute a population at risk for dementia. The level of emotional support should be included in risk assessments of dementia.

Investigating the potential mechanisms of depression induced-by COVID-19 infection in patients

The new coronavirus (COVID-19) has emerged now in the world as a pandemic. The SARS-CoV-2 infection causes variant common symptoms, such as dry cough, tiredness, dyspnea, fever, myalgia, chills, headache, chest pain, and conjunctivitis. Different organs may be affected by COVID-19, such as the respiratory system, gastrointestinal tract, kidneys, and CNS. However, the information about the COVID-19 infection in the CNS is insufficient. We do know that the virus can enter the central nervous system (CNS) via different routes, causing symptoms such as dizziness, headache, seizures, loss of consciousness, and depression. Depression is the most common disorder among all neurological symptoms following COVID-19 infection, although the mechanism of COVID-19-induced depression is not yet clear.

The aim of the present study is to investigate the probable mechanisms of COVID-19-induced depression.

The reasons for depression in infected patients may be due to social and pathological factors including social quarantine, economic problems, stress, changes in the HPA axis, inflammation due to the entry of proinflammatory cytokines into the CNS, production of inflammatory cytokines by microglia, mitochondrial disorders, damage to the hippocampus, and malnutrition.

By evaluating different factors involved in COVID-19-induced depression, we have concluded that depression can be minimized by controlling stress, preventing the cytokine storm with appropriate anti-inflammatory drugs, and proper nutrition.

Enriched environment enhances histone acetylation of NMDA receptor in the hippocampus and improves cognitive dysfunction in aged mice

The mechanisms of age-associated memory impairment may be associated with glutamate receptor function and chromatin modification. To observe the effect of an enriched environment on the cognitive function of mice with age-associated memory impairment, 3-month-old C57BL/6 male mice ("young" mice) were raised in a standard environment, while 24-month-old C57BL/6 male mice with memory impairment ("age-associated memory impairment" mice) were raised in either a standard environment or an enriched environment. The enriched environment included a variety of stimuli involving movement and sensation. A water maze test was then used to measure cognitive function in the mice. Furthermore, quantitative real-time polymerase chain reaction and western blot assays were used to detect right hippocampal GluN2B mRNA as well as protein expression of GluN2B and CREB binding protein in all mice. In addition, chromatin immunoprecipitation was used to measure the extent of histone acetylation of the hippocampal GluN2B gene promoters. Compared with the young mice, the water maze performance of age-associated memory impairment mice in the standard environment was significantly decreased. In addition, there were significantly lower levels of total histone acetylation and expression of CREB binding protein in the hippocampus of age-associated memory impairment mice in the standard environment compared with the young mice. There were also significantly lower levels of histone acetylation, protein expression, and mRNA expression of GluN2B in the hippocampus of these mice. In contrast, in the age-associated memory impairment mice with the enriched environment intervention, the water maze performance and molecular biological indexes were significantly improved. These data confirm that an enriched environment can improve cognitive dysfunction in age-associated memory impairment mice, and suggest that the mechanisms may be related to the increased expression of CREB binding protein and the increased degree of total histone acetylation in the hippocampus of age-associated memory impairment mice, which may cause the increase of histone acetylation of GluN2B gene promoter and the enhancement of GluN2B mRNA transcription and protein expression in hippocampus. The animal experiment was approved by the Animal Ethics Committee of Yangzhou University, China (approval No. 20170312001) in March 2017.

The effect of age of first exposure to competitive fighting on cognitive and other neuropsychiatric symptoms and brain volume

It has long been established that fighting sports such as boxing and mixed martial arts can lead to head injury. Prior work from this group on the Professional Fighters Brain Health Study found that exposure to repetitive head impacts is associated with lower brain volumes and decreased processing speed in fighters. Current and previously licensed professional fighters were recruited, divided into active and retired cohorts, and matched with a control group that had no prior experience in sports with likely head trauma. This study examined the relationship between age of first exposure (AFE) to fighting sports and brain structure (MRI regional volume), cognitive performance (CNS Vital Signs, iComet C3), and clinical neuropsychiatric symptoms (PHQ-9, Barratt Impulsiveness Scale). Brain MRI data showed significant correlations between earlier AFE and smaller bilateral hippocampal and posterior corpus callosum volumes for both retired and active fighters. Earlier AFE in active fighters was correlated with decreased processing speed and decreased psychomotor speed. Retired fighters showed a correlation between earlier AFE and higher measures of depression and impulsivity. Overall, the results help to inform clinicians, governing bodies, parents, and athletes of the risks associated with beginning to compete in fighting sports at a young age.