Elevation of plasma phosphorylated tau181 during neurological illnesses affecting consciousness and kidney dysfunction

ATN blood biomarkers are related to digital cognitive assessment in type 1 diabetes

INTRODUCTION

Associations between amyloid-tau-neurodegeneration (ATN) plasma biomarkers and cognition have not been characterized in adults with type 1 diabetes (T1D).

METHODS

Using data from participants in the Glycemic Variability and Fluctuations in Cognitive Status in Adults with T1D (GluCog) study (N = 114), we evaluated associations between phosphorylated tau (pTau)181, pTau217, β-amyloid 42/40 ratio, glial fibrillary acidic protein (GFAP), and neurofilament light (NfL) and self-administered digital cognitive tests, adjusting for age, sex, education, comorbidities (e.g., kidney disease), and glycemic indices.

RESULTS

Higher concentrations of pTau181 and GFAP were associated with slower responses on working memory tasks (pTau181: β = 0.261; p = 0.007; GFAP: β = 0.175, p = 0.036), and higher β-amyloid 42/40 ratio was associated with better vocabulary (β = 0.260, p = 0.009).

Discussion

Digital cognitive performance was associated with several ATN plasma biomarkers in T1D adults. Prospective studies are needed to understand the utility of these biomarkers in T1D.

Highlights

There is an increase in life expectancy for individuals with type 1 diabetes (T1D).Few studies investigate the relationship between T1D and neurodegeneration.We characterize the relation between ATN plasma biomarkers and cognitive function.Digital cognitive performance was associated with plasma biomarkers in T1D adults.

Is blood pTau a reliable indicator of the CSF status? A narrative review

BACKGROUND

The identification of biomarkers for the early diagnosis of Alzheimer's disease (AD) is a crucial goal of the current research. Blood biomarkers are less invasive, easier to obtain and achievable by a cheaper means than those on cerebrospinal fluid (CSF) and significantly more economic than functional neuroimaging investigations; thus, a great interest is focused on blood isoforms of the phosphorylated Tau protein (pTau), indicators of ongoing tau pathology (i.e. neurofibrillary tangles, NFTs, an AD neuropathological hallmark) in the central nervous system (CNS). However, current data often highlight discordant results about the ability of blood pTau to predict CSF status.

OBJECTIVE

We aim to synthesise the studies that compared pTau levels on CSF and blood to assess their correlation in AD continuum.

METHODS

We performed a narrative literature review using, first, MEDLINE (via PubMed) by means of MeSH terms, and then, we expanded the reults by means of Scopus and Web of Sciences to be as inclusive as possible. Finally, we added work following an expert opinion. Only papers presenting original data on pTau values on both blood and CSF were included.

RESULTS

The 33 included studies show an extreme heterogeneity in terms of pTau isoform (pTau181, 217 and 231), laboratory methods, diagnostic criteria and choice of comparison groups. Most studies evaluated plasma pTau181, while data on other isoforms and serum are scarcer.

DISCUSSION

Most papers identify a correlation between CSF and blood measurements. Furthermore, even when not specified, it is often possible to show an increase in blood pTau values as AD-related damage progresses in the AD continuum and higher values in AD than in other neurodegenerative diseases. Notably, plasma pTau231 seems the first biomarker to look for in the earliest and pre-clinical stages, quickly followed by pTau217 and, finally, by pTau181.

CONCLUSIONS

Our results encourage the use of blood pTau for the early identification of patients with AD continuum.