Fluid biomarkers of the neurovascular unit in cerebrovascular disease and vascular cognitive disorders: A systematic review and meta-analysis

Background

The disruption of the neurovascular unit (NVU), which maintains the integrity of the blood brain barrier (BBB), has been identified as a critical mechanism in the development of cerebrovascular and neurodegenerative disorders. However, the understanding of the pathophysiological mechanisms linking NVU dysfunction to the disorders is incomplete, and reliable blood biomarkers to measure NVU dysfunction are yet to be established. This systematic review and meta-analysis aimed to identify biomarkers associated with BBB dysfunction in large vessel disease, small vessel disease (SVD) and vascular cognitive disorders (VCD).

Methods

A literature search was conducted in PubMed, EMBASE, Scopus and PsychINFO to identify blood biomarkers related to dysfunction of the NVU in disorders with vascular pathologies published until 20 November 2023. Studies that assayed one or more specific markers in human serum or plasma were included. Quality of studies was assessed using the Newcastle-Ottawa Quality Assessment Scale. Effects were pooled and methodological heterogeneity examined using the random effects model.

Results

A total of 112 studies were included in this review. Where study numbers allowed, biomarkers were analysed using random effect meta-analysis for VCD (1 biomarker; 5 studies) and cerebrovascular disorders, including stroke and SVD (9 biomarkers; 29 studies) while all remaining biomarkers (n = 17 biomarkers; 78 studies) were examined through qualitative analysis. Results of the meta-analysis revealed that cerebrospinal fluid/serum albumin quotient (Q-Alb) reliably differentiates VCD patients from healthy controls (MD = 2.77; 95 % CI = 1.97-3.57; p < 0.0001) while commonly measured biomarkers of endothelial dysfunction (VEGF, VCAM-1, ICAM-1, vWF and E-selectin) and neuronal injury (NfL) were significantly elevated in vascular pathologies. A qualitative assessment of non-meta-analysed biomarkers revealed NSE, NfL, vWF, ICAM-1, VCAM-1, lipocalin-2, MMP-2 and MMP-9 levels to be upregulated in VCD, although these findings were not consistently replicated.

Conclusions

This review identifies several promising biomarkers of NVU dysfunction which require further validation. A panel of biomarkers representing multiple pathophysiological pathways may offer greater discriminative power in distinguishing possible disease mechanisms of VCD.

Social connections and risk of incident mild cognitive impairment, dementia, and mortality in 13 longitudinal cohort studies of ageing

INTRODUCTION

Previous meta-analyses have linked social connections and mild cognitive impairment, dementia, and mortality. However, these used aggregate data from North America and Europe and examined a limited number of social connection markers.

METHODS

We used individual participant data (N = 39271, Mage  = 70.67 (40-102), 58.86% female, Meducation  = 8.43 years, Mfollow-up  = 3.22 years) from 13 longitudinal ageing studies. A two-stage meta-analysis of Cox regression models examined the association between social connection markers with our primary outcomes.

RESULTS

We found associations between good social connections structure and quality and lower risk of incident mild cognitive impairment (MCI); between social structure and function and lower risk of incident dementia and mortality. Only in Asian cohorts, being married/in a relationship was associated with reduced risk of dementia, and having a confidante was associated with reduced risk of dementia and mortality.

DISCUSSION

Different aspects of social connections - structure, function, and quality - are associated with benefits for healthy aging internationally.

HIGHLIGHTS

Social connection structure (being married/in a relationship, weekly community group engagement, weekly family/friend interactions) and quality (never lonely) were associated with lower risk of incident MCI. Social connection structure (monthly/weekly friend/family interactions) and function (having a confidante) were associated with lower risk of incident dementia. Social connection structure (living with others, yearly/monthly/weekly community group engagement) and function (having a confidante) were associated with lower risk of mortality. Evidence from 13 longitudinal cohort studies of ageing indicates that social connections are important targets for reducing risk of incident MCI, incident dementia, and mortality. Only in Asian cohorts, being married/in a relationship was associated with reduced risk of dementia, and having a confidante was associated with reduced risk of dementia and mortality.

Genetically Predicted Blood Pressure and Cognition in Midlife: A UK Biobank Study

BACKGROUND

This UK Biobank study uses a mendelian randomization approach to mitigate the variability and confounding that has affected previous analyses of the relationship between measured blood pressure (BP) and cognition and thus delineate the true association between the two.

METHODS

Systolic BP (SBP) and diastolic BP polygenic risk scores (PRSs) were calculated using summary statistics from the International Consortium of Blood Pressure-Genome Wide Association Study (n=299 024). Adjusted nonlinear mixed-effects regression models were used, including a natural splines term for BP-PRS with outcomes of fluid intelligence, reaction time (RT), and composite attention score. Moderating effects of age, sex, and antihypertensive use were assessed in separate models.

RESULTS

There were 448 575 participants (mean age, 56.3 years; age range, 37-72 years) included in the analysis after genetic and neurological disease exclusions. Genetic propensity for high SBP had an approximately linear association with worsened fluid intelligence (P=0.0018). This relationship was significantly moderated by age (P<0.0001). By contrast, genetic propensity for high and low SBP and diastolic BP predicted worse attention function (P=0.0099 and P=0.0019), with high PRSs predicting worse function than low PRSs. Genetic propensity for low SBP and diastolic BP was associated with considerably worse RTs, while for high SBP-PRSs, the RT plateaued (P<0.0001). The relationships between RT and the PRSs were significantly moderated by sex (P<0.0001) and antihypertensive use (P<0.0001).

CONCLUSIONS

Genetic propensity for high and low BP impacts on midlife cognition in subtle ways and differentially affects cognitive domains. While a genetic propensity to low BP may preserve nontimed tests in midlife, it may come at a trade-off with worsened attention scores and RT.

Use of Antihypertensives, Blood Pressure, and Estimated Risk of Dementia in Late Life: An Individual Participant Data Meta-Analysis

Importance

The utility of antihypertensives and ideal blood pressure (BP) for dementia prevention in late life remains unclear and highly contested.

Objectives

To assess the associations of hypertension history, antihypertensive use, and baseline measured BP in late life (age >60 years) with dementia and the moderating factors of age, sex, and racial group.

Data Source and Study Selection

Longitudinal, population-based studies of aging participating in the Cohort Studies of Memory in an International Consortium (COSMIC) group were included. Participants were individuals without dementia at baseline aged 60 to 110 years and were based in 15 different countries (US, Brazil, Australia, China, Korea, Singapore, Central African Republic, Republic of Congo, Nigeria, Germany, Spain, Italy, France, Sweden, and Greece).

Data Extraction and Synthesis

Participants were grouped in 3 categories based on previous diagnosis of hypertension and baseline antihypertensive use: healthy controls, treated hypertension, and untreated hypertension. Baseline systolic BP (SBP) and diastolic BP (DBP) were treated as continuous variables. Reporting followed the Preferred Reporting Items for Systematic Review and Meta-Analyses of Individual Participant Data reporting guidelines.

Main Outcomes and Measures

The key outcome was all-cause dementia. Mixed-effects Cox proportional hazards models were used to assess the associations between the exposures and the key outcome variable. The association between dementia and baseline BP was modeled using nonlinear natural splines. The main analysis was a partially adjusted Cox proportional hazards model controlling for age, age squared, sex, education, racial group, and a random effect for study. Sensitivity analyses included a fully adjusted analysis, a restricted analysis of those individuals with more than 5 years of follow-up data, and models examining the moderating factors of age, sex, and racial group.

Results

The analysis included 17 studies with 34 519 community dwelling older adults (20 160 [58.4%] female) with a mean (SD) age of 72.5 (7.5) years and a mean (SD) follow-up of 4.3 (4.3) years. In the main, partially adjusted analysis including 14 studies, individuals with untreated hypertension had a 42% increased risk of dementia compared with healthy controls (hazard ratio [HR], 1.42; 95% CI 1.15-1.76; P = .001) and 26% increased risk compared with individuals with treated hypertension (HR, 1.26; 95% CI, 1.03-1.53; P = .02). Individuals with treated hypertension had no significant increased dementia risk compared with healthy controls (HR, 1.13; 95% CI, 0.99-1.28; P = .07). The association of antihypertensive use or hypertension status with dementia did not vary with baseline BP. There was no significant association of baseline SBP or DBP with dementia risk in any of the analyses. There were no significant interactions with age, sex, or racial group for any of the analyses.

Conclusions and Relevance

This individual patient data meta-analysis of longitudinal cohort studies found that antihypertensive use was associated with decreased dementia risk compared with individuals with untreated hypertension through all ages in late life. Individuals with treated hypertension had no increased risk of dementia compared with healthy controls.

Short-term Trajectories of Poststroke Cognitive Function: A STROKOG Collaboration Study

BACKGROUND AND OBJECTIVES

Past studies on post-stroke cognitive function have focused on the average performance or change over time, but few have investigated patterns of cognitive trajectories after stroke. This project used latent class growth analysis (LCGA) to identify clusters of patients with similar patterns of cognition scores over the first-year post-stroke and the extent to which long-term cognitive outcome is predicted by the clusters ("trajectory groups").

METHODS

Data were sought from the Stroke and Cognition consortium (STROKOG). LCGA was used to identify clusters of trajectories based on standardized global cognition scores at baseline (T₁) and at the 1-year follow-up (T₂). One-step IPD meta-analysis was used to examine risk factors for trajectory groups and association of trajectory groups with cognition at the long-term follow-up (T₃).

RESULTS

Nine hospital-based stroke cohorts with 1149 patients (63% male; mean age 66.4 years (SD=11.0)) were included. The median time assessed at T₁ was 3.6 months post-stroke, 1.0 year at T₂ and 3.2 years at T₃. LCGA identified 3 trajectory groups, which were characterized by different mean levels of cognition scores at T₁ (low-, -3.27SD (0.94), 17%; medium-, -1.23SD (0.68), 48%; and high-performance, 0.71SD (0.77), 35%). There was significant improvement in cognition for the high-performance group (0.22 SD/year, 95% CI 0.07, 0.36), but changes for the low and medium performance groups were not significant (-0.10 SD/year, 95% CI -0.33, 0.13; 0.11 SD/year, 95% CI -0.08, 0.24 respectively). Factors associated with the low- (versus high-) performance group include age (relative risk ratio [RRR] 1.18, 95% CI 1.14, 1.23), years of education (RRR 0.61, 95% CI 0.56, 0.67), diabetes (RRR 3.78, 95% CI 2.08, 6.88), large artery versus small vessel strokes (RRR 2.77, 95% CI 1.32, 5.83), and moderate/severe strokes (RRR 3.17, 95% 1.42, 7.08). Trajectory groups were predictive of global cognition at T₃, but its predictive power was comparable to scores at T₁.

CONCLUSION

The trajectory of cognitive function over the first-year post-stroke is heterogenous. Baseline cognitive function ∼3.6 months post-stroke is a good predictor of long-term cognitive outcome. Older age, lower levels of education, diabetes, large artery strokes, and greater stroke severity are risk factors for lower cognitive performance over the first year.

Performance-Based vs Informant-Reported Instrumental Activities of Daily Living in Predicting Dementia

OBJECTIVES

Identifying individuals at risk of developing dementia may be aided by early detection of functional impairments. The aims of the present study were to examine differences in informant-reported and performance-based measures of instrumental activities of daily living (IADL) and to assess whether a performance-based IADL measure contributes additional unique variance over informant reports in predicting incident dementia over 4 years.

DESIGN

Prospective cohort study (Sydney Memory and Ageing Study).

SETTING

Eastern Suburbs, Sydney, Australia.

PARTICIPANTS

307 community-dwelling individuals (60.6% female) aged between 76 and 96 years with normal cognition (NC; n = 190) or mild cognitive impairment (MCI; n = 117).

METHODS

IADL ability was assessed with the performance-based Sydney Test of Activities of Daily Living in Memory Disorders (STAM) and the Bayer-Activities of Daily Living (B-ADL) informant report, at baseline and 4-year follow-up. Covariates included age, sex, education, Mini-Mental State Examination and Geriatric Depression Scale scores, arthritis, vision impairment, cardiovascular risk, and number of medications. Logistic regressions were conducted to examine the longitudinal association between the 2 types of IADL measures and incident dementia.

RESULTS

Logistic regressions showed that performance-based IADL impairment at baseline [odds ratio (OR) = 0.83, 95% confidence interval (CI) 0.77, 0.90; P < .001] and decline in performance-based IADL function (OR = 0.82, 95% CI 0.73, 0.91; P < .001) were associated with incident dementia over 4 years, with the association provided by the STAM being statistically significant over and above the B-ADL.

CONCLUSIONS AND IMPLICATIONS

Performance-based measures of IADL can predict progression to dementia over 4 years beyond that provided by an informant report of IADL. Performance-based IADL measures are promising tools for clinical practice to identify individuals at greater risk of developing dementia.

Does Antihypertensive Use Moderate the Effect of Blood Pressure on Cognitive Decline in Older People?

BACKGROUND

While midlife hypertension is deleterious, late-life hypertension has been associated with better cognitive outcomes in several studies. Many questions remain, including the relative benefit or harm of a blood pressure (BP) target and antihypertensive therapy of <120 in very old individuals.

METHODS

The Sydney Memory and Aging Study (n = 1015) comprises a cohort of 70- to 90-year-olds, who were followed biennially for 8 years. Global cognition was assessed with a battery of 10 neuropsychological tests. Blood pressure was measured at Waves 1 and 2 and classified into 3 systolic groupings: group 1 (≤120 mmHg), group 2 (121-140 mmHg), and group 3 (>140 mmHg). Multiple regression, linear mixed modeling, and Cox regression examined the effect of BP and antihypertensives.

RESULTS

There were no overall significant differences in global cognition or dementia between the disparate BP groups. However, in those not taking antihypertensives, the systolic BP (SBP) > 140 mmHg group had a significantly worse global cognitive trajectory compared to SBP ≤ 120 mmHg (b = -0.067, 95% CI [-0.129, -0.006], p = .030). Within the SBP ≤ 120 mmHg group those taking antihypertensives had significantly worse global cognition trajectories compared to those not taking antihypertensives even when controlling for past history of hypertension (b = -0.077, 95% CI [-0.147, -0.007], p = .030).

CONCLUSIONS

Untreated hypertension in old age is related to worse global cognitive decline. However, ongoing treatment at new recommendations of lower SBP targets may be related to poorer cognitive decline and should be considered carefully in older populations.

Long-term relations among prosocial-media use, empathy, and prosocial behavior

Despite recent growth of research on the effects of prosocial media, processes underlying these effects are not well understood. Two studies explored theoretically relevant mediators and moderators of the effects of prosocial media on helping. Study 1 examined associations among prosocial- and violent-media use, empathy, and helping in samples from seven countries. Prosocial-media use was positively associated with helping. This effect was mediated by empathy and was similar across cultures. Study 2 explored longitudinal relations among prosocial-video-game use, violent-video-game use, empathy, and helping in a large sample of Singaporean children and adolescents measured three times across 2 years. Path analyses showed significant longitudinal effects of prosocial- and violent-video-game use on prosocial behavior through empathy. Latent-growth-curve modeling for the 2-year period revealed that change in video-game use significantly affected change in helping, and that this relationship was mediated by change in empathy.