CSF tau368/total-tau ratio reflects cognitive performance and neocortical tau better compared to p-tau181 and p-tau217 in cognitively impaired individuals.

Cerebrospinal fluid (CSF) tau biomarkers are reliable diagnostic markers for Alzheimer's disease (AD). However, their strong association with amyloid pathology may limit their reliability as specific markers of tau neurofibrillary tangles. A recent study showed evidence that a ratio of CSF C-terminally truncated tau (tau368, a tangle-enriched tau species), especially in ratio with total tau (t-tau), correlates strongly with tau PET tracer uptake. In this study, we set to evaluate the performance of the tau368/t-tau ratio in capturing tangle pathology, as indexed by a high-affinity tau PET tracer, as well as its association with severity of clinical symptoms. In total, 125 participants were evaluated cross-sectionally from the Translational Biomarkers of Aging and Dementia (TRIAD) cohort (21 young, 60 cognitively unimpaired [CU] elderly [15 Aβ+], 10 Aβ+ with mild cognitive impairment [MCI], 14 AD dementia patients, and 20 Aβ- individuals with non-AD cognitive disorders). All participants underwent amyloid and tau PET scanning, with [18F]-AZD4694 and [18F]-MK6240, respectively, and had CSF measurements of p-tau181, p-tau217, and t-tau. CSF concentrations of tau368 were quantified in all individuals with an in-house single molecule array assay. CSF tau368 concentration was not significantly different across the diagnostic groups, although a modest increase was observed in all groups as compared with healthy young individuals (all P < 0.01). In contrast, the CSF tau368/t-tau ratio was the lowest in AD dementia, being significantly lower than in CU individuals (Aβ-, P < 0.001; Aβ+, P < 0.01), as well as compared to those with non-AD cognitive disorders (P < 0.001). Notably, in individuals with symptomatic AD, tau368/t-tau correlated more strongly with [18F]-MK6240 PET SUVR as compared to the other CSF tau biomarkers, with increasing associations being seen in brain regions associated with more advanced disease (isocortical regions > limbic regions > transentorhinal regions). Importantly, linear regression models indicated that these associations were not confounded by Aβ PET SUVr. CSF tau368/t-tau also tended to continue to become more abnormal with higher tau burden, whereas the other biomarkers plateaued after the limbic stage. Finally, the tau368/t-tau ratio correlated more strongly with cognitive performance in individuals with symptomatic AD as compared to t-tau, p-tau217 and p-tau181. The tau368/t-tau ratio captures novel aspects of AD pathophysiology and disease severity in comparison to established CSF tau biomarkers, as it is more closely related to tau PET SUVR and cognitive performance in the symptomatic phase of the disease.

Simrén J ，Brum WS ，Ashton NJ ，Benedet AL ，Karikari TK ，Kvartsberg H ，Sjons E ，Lussier FZ ，Chamoun M ，Stevenson J ，Hopewell R ，Pallen V ，Ye K ，Pascoal TA ，Zetterberg H ，Rosa-Neto P ，Blennow K ... -  《Alzheimers Research & Therapy》

Biomarker-Based Prediction of Longitudinal Tau Positron Emission Tomography in Alzheimer Disease.

Leuzy A ，Smith R ，Cullen NC ，Strandberg O ，Vogel JW ，Binette AP ，Borroni E ，Janelidze S ，Ohlsson T ，Jögi J ，Ossenkoppele R ，Palmqvist S ，Mattsson-Carlgren N ，Klein G ，Stomrud E ，Hansson O ... -  《-》

Association of Phosphorylated Tau Biomarkers With Amyloid Positron Emission Tomography vs Tau Positron Emission Tomography.

Therriault J ，Vermeiren M ，Servaes S ，Tissot C ，Ashton NJ ，Benedet AL ，Karikari TK ，Lantero-Rodriguez J ，Brum WS ，Lussier FZ ，Bezgin G ，Stevenson J ，Rahmouni N ，Kunach P ，Wang YT ，Fernandez-Arias J ，Socualaya KQ ，Macedo AC ，Ferrari-Souza JP ，Ferreira PCL ，Bellaver B ，Leffa DT ，Zimmer ER ，Vitali P ，Soucy JP ，Triana-Baltzer G ，Kolb HC ，Pascoal TA ，Saha-Chaudhuri P ，Gauthier S ，Zetterberg H ，Blennow K ，Rosa-Neto P ... -  《-》

Clinical performance and head-to-head comparison of CSF p-tau235 with p-tau181, p-tau217 and p-tau231 in two memory clinic cohorts.

Cerebrospinal fluid (CSF) p-tau235 is a novel biomarker highly specific of Alzheimer's disease (AD). However, CSF p-tau235 has only been studied in well-characterized research cohorts, which do not fully reflect the patient landscape found in clinical settings. Therefore, in this multicentre study, we investigated the performance of CSF p-tau235 to detect symptomatic AD in clinical settings and compared it with CSF p-tau181, p-tau217 and p-tau231. CSF p-tau235 was measured using an in-house single molecule array (Simoa) assay in two independent memory clinic cohorts: Paris cohort (Lariboisière Fernand-Widal University Hospital Paris, France; n=212) and BIODEGMAR cohort (Hospital del Mar, Barcelona, Spain; n=175). Patients were classified by the syndromic diagnosis (cognitively unimpaired [CU], mild cognitive impairment [MCI] or dementia) and their biological diagnosis (amyloid-beta [Aβ]+ or Aβ -). Both cohorts included detailed cognitive assessments and CSF biomarker measurements (clinically validated core AD biomarkers [Lumipulse CSF Aβ1-42/40 ratio, p-tau181 and t-tau] and in-house developed Simoa CSF p-tau181, p-tau217 and p-tau231). High CSF p-tau235 levels were strongly associated with CSF amyloidosis regardless of the clinical diagnosis, being significantly increased in MCI Aβ+ and dementia Aβ+ when compared with all other Aβ- groups (Paris cohort: P ˂0.0001 for all; BIODEGMAR cohort: P ˂0.05 for all). CSF p-tau235 was pronouncedly increased in the A+T+ profile group compared with A-T- and A+T- groups (P ˂0.0001 for all). Moreover, CSF p-tau235 demonstrated high diagnostic accuracies identifying CSF amyloidosis in symptomatic cases (AUCs=0.86 to 0.96) and discriminating AT groups (AUCs=0.79 to 0.98). Overall, CSF p-tau235 showed similar performances to CSF p-tau181 and CSF p-tau231 when discriminating CSF amyloidosis in various scenarios, but lower than CSF p-tau217. Finally, CSF p-tau235 associated with global cognition and memory domain in both cohorts. CSF p-tau235 was increased with the presence of CSF amyloidosis in two independent memory clinic cohorts. CSF p-tau235 accurately identified AD in both MCI and dementia patients. Overall, the diagnostic performance of CSF p-tau235 was comparable to that of other CSF p-tau measurements, indicating its suitability to support a biomarker-based AD diagnosis in clinical settings.

Lantero-Rodriguez J ，Vrillon A ，Fernández-Lebrero A ，Ortiz-Romero P ，Snellman A ，Montoliu-Gaya L ，Brum WS ，Cognat E ，Dumurgier J ，Puig-Pijoan A ，Navalpotro-Gómez I ，García-Escobar G ，Karikari TK ，Vanmechelen E ，Ashton NJ ，Zetterberg H ，Suárez-Calvet M ，Paquet C ，Blennow K ... -  《Alzheimers Research & Therapy》

Correlation between Cerebrospinal Fluid Core Alzheimer's Disease Biomarkers and β-Amyloid PET in Chinese Dementia Population.

Xie Q ，Ni M ，Gao F ，Dai LB ，Lv XY ，Zhang YF ，Shi Q ，Zhu XX ，Xie JK ，Shen Y ，Wang SC ... -  《-》