Introduction Phosphorylated tau (p‐tau) in cerebrospinal fluid (CSF) is an established Alzheimer's disease (AD) biomarker. Novel immunoassays targeting N‐terminal and mid‐region p‐tau181 and p‐tau217 fragments are available, but head‐to‐head comparison in clinical settings is lacking. Methods N‐terminal‐directed p‐tau217 (N‐p‐tau217), N‐terminal‐directed p‐tau181 (N‐p‐tau181), and standard mid‐region p‐tau181 (Mid‐p‐tau181) biomarkers in CSF were evaluated in three cohorts (n = 503) to assess diagnostic performance, concordance, and associations with amyloid beta (Aβ). Results CSF N‐p‐tau217 and N‐p‐tau181 had better concordance (88.2%) than either with Mid‐p‐tau181 (79.7%–82.7%). N‐p‐tau217 and N‐p‐tau181 were significantly increased in early mild cognitive impairment (MCI)‐AD (A+T–N–) without changes in Mid‐p‐tau181 until AD‐dementia. N‐p‐tau217 and N‐p‐tau181 identified Aβ pathophysiology (area under the curve [AUC] = 94.8%–97.1%) and distinguished MCI‐AD from non‐AD MCI (AUC = 82.6%–90.5%) signficantly better than Mid‐p‐tau181 (AUC = 91.2% and 70.6%, respectively). P‐tau biomarkers equally differentiated AD from non‐AD dementia (AUC = 99.1%–99.8%). Discussion N‐p‐tau217 and N‐p‐tau181 could improve diagnostic accuracy in prodromal‐AD and clinical trial recruitment as both identify Aβ pathophysiology and differentiate early MCI‐AD better than Mid‐p‐tau181.

Objective. To determine the prevalence of anticardiolipin antibodies (aCL), anti-␤ 2 -glycoprotein I (anti-␤ 2 GPI) antibodies, and lupus anticoagulant (LAC) in a large cohort of children with systemic lupus erythematosus (SLE), and to evaluate the associations with neuropsychiatric manifestations. Methods. A single-center retrospective cohort study with longitudinal followup of antiphospholipid antibodies (aPL) in 137 children with SLE (25 boys and 112 girls, mean age at diagnosis 13.0 years) was performed. Patients were followed up for a mean of 31 months. Results. At the time of diagnosis, 65% of the children were aCL positive, 41% had anti-␤ 2 GPI antibodies, and 26% were LAC positive. Analysis of the association between presence of aPL and individual neuropsychiatric manifestations at diagnosis showed a statistically significant association of positive LAC with cerebrovascular disease (5 patients; P ‫؍‬ 0.015). A persistently positive aCL was observed in 50%, anti-␤ 2 GPI antibodies in 29%, and LAC in 16% of children over time. The prevalence of anti-␤ 2 GPI antibodies, but not aCL and LAC, was found to be statistically significantly higher in children with neuropsychiatric disease compared with those without (P ‫؍‬ 0.02). Comparison for specific neuropsychiatric manifestations showed a statistically significant association between a persistently positive LAC and chorea (2 patients; P ‫؍‬ 0.02). Conclusion. The prevalence of anti-␤ 2 GPI antibodies was found to be higher in the group of SLE patients with neuropsychiatric disease compared with those without. Our data suggest an association between LAC and cerebrovascular disease at the time of SLE diagnosis and chorea over the disease course, but not between aPL and other neuropsychiatric manifestations.

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This is the largest cohort to date focusing on the prevalence of anti-Ku antibodies in patients with SSc. The case-control approach was able to demonstrate a clinically distinct subset of anti-Ku positive patients with SSc with only relative clinical differences in skeletal features. However, the notable exceptions were signs of myositis. This shows the importance of anti-Ku antibody detection for the prediction of this specific clinical subset.