Assessment of High Risk for Alzheimer's Disease Using Plasma Biomarkers in Subjects with Normal Cognition in Taiwan: A Preliminary Study

Longitudinal assessment of plasma biomarkers for early detection of cognitive changes in subjective cognitive decline

Background

Individuals experiencing subjective cognitive decline (SCD) are at an increased risk of developing mild cognitive impairment and dementia. Early identification of SCD and neurodegenerative diseases using biomarkers may help clinical decision-making and improve prognosis. However, few cross-sectional and longitudinal studies have explored plasma biomarkers in individuals with SCD using immunomagnetic reduction.

Objective

To identify plasma biomarkers for SCD.

Methods

Fifty-two participants [38 with SCD, 14 healthy controls (HCs)] underwent baseline assessments, including measurements of plasma Aβ42, Aβ40, t-tau, p-tau, and α-synuclein using immunomagnetic reduction (IMR) assays, cognitive tests and the Mini-Mental State Examination (MMSE). Following initial cross-sectional analysis, 39 individuals (29 with SCD, 10 HCs) entered a longitudinal phase for reassessment of these biomarkers and the MMSE. Biomarker outcomes across different individual categories were primarily assessed using the area under the receiver operating characteristic (ROC) curve. The SCD subgroup with an MMSE decline over one point was compared to those without such a decline.

Results

Higher baseline plasma Aβ1-42 levels significantly discriminated participants with SCD from HCs, with an acceptable area under the ROC curve (AUC) of 67.5% [95% confidence interval (CI), 52.7-80.0%]. However, follow-up and changes in MMSE and IMR data did not significantly differ between the SCD and HC groups (p > 0.05). Furthermore, lower baseline plasma Aβ1-42 levels were able to discriminate SCD subgroups with and without cognitive decline with a satisfied performance (AUC, 75.0%; 95% CI, 55.6-89.1%). At last, the changes in t-tau and Aβ42 × t-tau could differentiate between the two SCD subgroups (p < 0.05).

Conclusion

Baseline plasma Aβ42 may help identify people with SCD and predict SCD progression. The role of plasma Aβ42 levels as well as their upward trends from baseline in cases of SCD that progress to mild cognitive impairment and Alzheimer's disease require further investigation.

H3K27 acetylation-induced FSTL1 upregulation by P300/RUNX1 co-activation exacerbated autophagy-mediated neuronal damage and NF-κB-stimulated inflammation in Alzheimer's disease

Follistatin-like protein 1 (FSTL1) has been demonstrated to participate in the pathogenesis of several neurological diseases. The current study informed the role of H3K27 acetylation-induced FSTL1 upregulation in Alzheimer's disease (AD). Our investigation discovered the upregulated FSTL1 expression and enhanced autophagy activity in AD. FSTL1 knockdown successfully attenuated the injuries of Aβ1-42-challenged SH-SY5Y cells through the inhibition of autophagy activity. Besides, FSTL1 deficiency suppresses the inflammatory response and NF-κB signaling in AD. Moreover, it was found that p300 was recruited by transcriptional factor RUNX1 to stimulate the H3K27 acetylation in FSTL1 promoter region, which caused the upregulation of FSTL1 in AD. To summarize, p300 acted as a co-activator of RUNX1 to trigger the activation of FSTL1 in AD, resulting in the exacerbated injuries and inflammatory responses of Aβ1-42-induced SH-SY5Y cells.

Relevance of plasma biomarkers to pathologies in Alzheimer's disease, Parkinson's disease and frontotemporal dementia

Amyloid plaques and tau tangles are pathological hallmarks of Alzheimer's disease (AD). Parkinson's disease (PD) results from the accumulation of α-synuclein. TAR DNA-binding protein (TDP-43) and total tau protein (T-Tau) play roles in FTD pathology. All of the pathological evidence was found in the biopsy. However, it is impossible to perform stein examinations in clinical practice. Assays of biomarkers in plasma would be convenient. It would be better to investigate the combinations of various biomarkers in AD, PD and FTD. Ninety-one subjects without neurodegenerative diseases, 76 patients with amnesic mild cognitive impairment (aMCI) or AD dementia, combined as AD family, were enrolled. One hundred and nine PD patients with normal cognition (PD-NC) or dementia (PDD), combined as PD family, were enrolled. Twenty-five FTD patients were enrolled for assays of plasma amyloid β 1-40 (Aβ_1-40), Aβ_1-42, T-Tau, α-synuclein and TDP-43 using immunomagnetic reduction (IMR). The results show that Aβs and T-Tau are major domains in AD family. α-synuclein is highly dominant in PD family. FTD is closely associated with TDP-43 and T-Tau. The dominant plasma biomarkers in AD family, PD family and FTD are consistent with pathology. This implies that plasma biomarkers are promising for precise and differential assessments of AD, PD and FTD in clinical practice.

A Profile of Nanoparticle-Based Plasma Neurodegenerative Biomarkers for Cognitive Function Among Patients Undergoing Hemodialysis

Purpose

This study aimed to compare the plasma levels of nanoparticle-based neurodegenerative biomarkers between hemodialysis (HD) participants with grossly normal cognitive function and healthy controls.

Patients and Methods

A cohort of participants undergoing maintenance HD and healthy controls were enrolled for comparison between July and October 2021. The immunomagnetic reduction method was used to measure plasma neurodegenerative biomarkers Aβ_1-40, Aβ_1-42, tau protein, and neurofilament light chain (NfL). The clinical dementia rating (CDR) was used to evaluate cognitive function. A receiver operating characteristic curve was used to discriminate between HD participants and healthy controls.

Results

There were 52 and 18 participants in the HD and healthy control groups, respectively. The mean age of the HD participants was 62 years, and that of the healthy controls was 57 years. The mean HD vintage in the HD cohort was 11.8 years. HD participants demonstrated significantly higher plasma levels of Aβ_1-42, tau protein, Aβ_1-42 × tau, and NfL and Aβ_1-42/Aβ_1-40 ratio and significantly lower plasma Aβ_1-40 levels than healthy controls. The measured plasma biomarkers could not discriminate between CDR0 and CDR0.5 HD participants. The area under the curve of the study biomarkers to discriminate HD participants from healthy controls ranged from 0.987 (Aβ_1-42 × tau) to 0.889 (NfL).

Conclusion

The plasma levels of nanoparticle-based neurodegenerative biomarkers were higher in HD participants with grossly normal cognitive function than in healthy controls. These findings imply that neurodegenerative changes appear in HD participants. A profile of plasma neurodegenerative biomarkers could be considered a potential surrogate for evaluating long-term cognitive function in HD participants.