Age Matching Is Essential for the Study of Cerebrospinal Fluid sTREM2 Levels and Alzheimer's Disease Risk: A Meta-Analysis

The longitudinal trajectory of CSF sTREM2: the alzheimer's disease neuroimaging initiative

BACKGROUND

The soluble triggering receptor expressed on myeloid cells 2 (sTREM2) in cerebrospinal fluid (CSF) is considered a biomarker of microglia activity. The objective of this study was to investigate the trajectory of CSF sTREM2 levels over time and examine its association with sex.

METHODS

A total of 1,017 participants from the Alzheimer's Disease Neuroimaging Initiative Study (ADNI) with at least one CSF sTREM2 record were included. The trajectory of CSF sTREM2 was analyzed using a growth curve model. The association between CSF sTREM2 levels and sex was assessed using linear mixed-effect models.

RESULTS

CSF sTREM2 levels were increased with age over time (P < 0.0001). No significant sex difference was observed in sTREM2 levels across the entire sample; however, among the APOE ε4 allele carriers, women exhibited significantly higher sTREM2 levels than men (β = 0.146, P = 0.002).

CONCLUSION

Our findings highlight the association between CSF sTREM2 levels and age-related increments, underscoring the potential influence of aging on sTREM2 dynamics. Furthermore, our observations indicate a noteworthy association between sex and CSF sTREM2 levels, particularly in individuals carrying the APOE ε4 allele.

Association of soluble TREM2 with Alzheimer's disease and mild cognitive impairment: a systematic review and meta-analysis

Objective

Soluble triggering receptor expressed on myeloid cells 2 (sTREM2) is a potential neuroinflammatory biomarker linked to the pathogenesis of Alzheimer's disease (AD) and mild cognitive impairment (MCI). Previous studies have produced inconsistent results regarding sTREM2 levels in various clinical stages of AD. This study aims to establish the correlation between sTREM2 levels and AD progression through a meta-analysis of sTREM2 levels in cerebrospinal fluid (CSF) and blood.

Methods

Comprehensive searches were conducted in PubMed, Embase, Web of Science, and the Cochrane Library to identify observational studies reporting CSF and blood sTREM2 levels in AD patients, MCI patients, and healthy controls. A random effects meta-analysis was used to calculate the standardized mean difference (SMD) and 95% confidence intervals (CIs).

Results

Thirty-six observational studies involving 3,016 AD patients, 3,533 MCI patients, and 4,510 healthy controls were included. CSF sTREM2 levels were significantly higher in both the AD [SMD = 0.28, 95% CI (0.15, 0.41)] and MCI groups [SMD = 0.30, 95% CI (0.13, 0.47)] compared to the healthy control group. However, no significant differences in expression were detected between the AD and MCI groups [SMD = 0.09, 95% CI (-0.09, 0.26)]. Furthermore, increased plasma sTREM2 levels were associated with a higher risk of AD [SMD = 0.42, 95% CI (0.01, 0.83)].

Conclusion

CSF sTREM2 levels are positively associated with an increased risk of AD and MCI. Plasma sTREM2 levels were notably higher in the AD group than in the control group and may serve as a promising biomarker for diagnosing AD. However, sTREM2 levels are not effective for distinguishing between different disease stages of AD. Further investigations are needed to explore the longitudinal changes in sTREM2 levels, particularly plasma sTREM2 levels, during AD progression.

Systematic review registration

https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42024514593.

High prevalence of subjective cognitive decline in older Chinese adults: a systematic review and meta-analysis

Background

Subjective cognitive decline (SCD) is considered a preclinical stage of Alzheimer's disease. However, reliable prevalence estimates of SCD in the Chinese population are lacking, underscoring the importance of such metrics for policymakers to formulate appropriate healthcare strategies.

Objective

To systematically evaluate SCD prevalence among older Chinese adults.

Methods

PubMed, Web of Science, The Cochrane Library, Embase, CNKI, Wanfang, VIP, CBM, and Airiti Library databases were searched for studies on SCD in older Chinese individuals published before May 2023. Two investigators independently screened the literature, extracted the information, and assessed the bias risk of the included studies. A meta-analysis was then conducted using Stata 16.0 software via a random-effects model to analyze SCD prevalence in older Chinese adults.

Results

A total of 17 studies were included (n = 31,782). The SCD prevalence in older Chinese adults was 46.4% (95% CI, 40.6-52.2%). Further, subgroup analyzes indicated that SCD prevalence was 50.8% in men and 58.9% among women. Additionally, SCD prevalence in individuals aged 60-69, 70-79, and ≥ 80 years was 38.0, 45.2, and 60.3%, respectively. Furthermore, SCD prevalence in older adults with BMI <18.5, 18.5-24.0, and > 24.0 was 59.3, 54.0, and 52.9%, respectively. Geographically, SCD prevalence among older Chinese individuals was 41.3% in North China and 50.0% in South China. In terms of residence, SCD prevalence was 47.1% in urban residents and 50.0% among rural residents. As for retired individuals, SCD prevalence was 44.2% in non-manual workers and 49.2% among manual workers. In the case of education, individuals with an education level of "elementary school and below" had an SCD prevalence rate of 62.8%; "middle school, "52.4%; "high school, "55.0%; and "college and above, "51.3%. Finally, SCD prevalence was lower among married individuals with surviving spouses than in single adults who were divorced, widowed, or unmarried.

Conclusion

Our systematic review and meta-analysis identified significant and widespread SCD prevalence in the older population in China. Therefore, our review findings highlight the urgent requirement for medical institutions and policymakers across all levels to prioritize and rapidly develop and implement comprehensive preventive and therapeutic strategies for SCD.Systematic review registration: https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42023406950, identifier: CRD42023406950.

Association between Cerebrospinal Fluid Soluble TREM2, Alzheimer's Disease and Other Neurodegenerative Diseases

BACKGROUND

Cerebrospinal fluid (CSF) soluble triggering receptor expressed on myeloid cells 2 (sTREM2) is a potential biomarker and therapy target for neurodegenerative diseases (NDDs). The purpose of this meta-analysis was to investigate the association between CSF sTREM2 level and NDDs, and to reveal the dynamic changes in CSF sTREM2 level in Alzheimer's disease (AD) continuum.

METHODS

We systematically searched PubMed, Embase, Web of Science, and Cochrane Library databases for observational studies, which compared the levels of CSF sTREM2 between NDDs and controls. Sources of heterogeneity were analyzed using sensitivity analysis, subgroup analysis and meta-regression. We assessed pooled data using a random-effects model.

RESULTS

Twenty-two observational studies which included 5716 participates were identified. Compared with the controls, the whole AD continuum group showed a significant increase in CSF sTREM2 level (standardized mean difference [SMD]: 0.41, 95% confidence intervals [CI]: 0.24, 0.58, p < 0.001). The mild cognitive impairment (MCI) group displayed the largest effect size (SMD, 0.49 [95% CI: 0.10, 0.88], p = 0.014), followed by the AD cohort (SMD, 0.40 [95% CI: 0.18, 0.63], p < 0.001). The increase in sTREM2 in the preclinical stage of AD (pre-AD) group was the lowest (SMD, 0.29 [95% CI: 0.03, 0.55], p = 0.031). Other NDDs also showed an increase in the CSF sTREM2 levels compared with control groups (SMD, 0.77 [95% CI: 0.37, 1.16], p < 0.001).

CONCLUSIONS

The pooled data confirmed that NDDs are associated with increased CSF sTREM2 level, thereby suggesting the CSF sTREM2 as a potential dynamic biomarker and therapy target for NDDs.

Cerebrospinal Fluid sTREM2 in Alzheimer’s Disease Is Associated with Both Amyloid and Tau Pathologies but not with Cognitive Status

Background: Cerebrospinal fluid (CSF) soluble triggering receptor expressed on myeloid cells 2 (sTREM2) is considered a biomarker of microglial activation. The relationships between CSF sTREM2 levels and Alzheimer’s disease (AD) CSF core biomarkers, cognitive status, and neurodegeneration remain unclear. Objective: To assess the association between CSF sTREM2 levels and AD progression and other AD hallmarks. Methods: Using the Alzheimer’s Disease Neuroimaging Initiative database, we investigated 1,035 participants, including 310 cognitively normal controls, 527 patients with mild cognitive impairment, and 198 patients with dementia. They were grouped according to CSF pathology (A/T profile) severity. CSF sTREM2 levels were compared between the groups, and linear regression analysis was performed to evaluate the factors affecting sTREM2 levels. The predictive effectiveness of sTREM2 levels was tested, and the correlation with other indicators was explored. The increase rate was assessed using linear mixed-effects models. Results: Higher CSF sTREM2 levels were associated with older age as well as higher CSF p-tau or t-tau and amyloid-β levels (all p <  0.001), but not with cognitive status. sTREM2 levels were not correlated with the baseline or longitudinal scale and neuroimaging result changes, and could not predict clinical conversion, but were correlated with multiple non-amyloid-β and non-tau CSF cytokines related to inflammation and neurodegeneration (p <  0.0001). The increased sTREM2 expression rate did not change among groups. Conclusion: CSF sTREM2 levels were jointly determined by age, amyloid-β, and tau pathologies, leading to complex AD cognitive continuum changes. Although sTREM2 levels could not predict cognitive deterioration and neurodegeneration, they could reflect the microglial state as a non-specific biomarker.