Piura, Yoav

Abstract INTRODUCTION Plasma biomarkers of Alzheimer's disease (AD) represent accessible alternatives to positron emission tomography (PET) and cerebrospinal fluid (CSF)‐based biomarkers in well‐characterized cohorts. It remains to be determined whether performance is maintained in outpatient clinics comprised of patients with multiple causes of cognitive impairment. METHODS Plasma phosphorylated tau217 (p‐tau217) and amyloid beta (Aβ) 42/40 were measured in 509 patients evaluated in a tertiary‐care memory clinic. Biomarker performance was compared across diagnoses, referencing established cutpoints for positive and negative biomarkers. RESULTS Plasma p‐tau217 distinguished patients with diagnoses of symptomatic AD with 95% sensitivity and 82% specificity. Integration of Aβ42 measurements (p‐tau217/Aβ42) incrementally improved specificity (86%). Plasma p‐tau217 and p‐tau217/Aβ42 concentrations closely associated with established CSF biomarkers of AD (area under the curve [AUC]: 0.94 and 0.96, respectively). Reduced kidney function associated with elevated plasma p‐tau217 and p‐tau217/Aβ42 concentrations in patients without AD (referencing CSF biomarkers). DISCUSSION Plasma p‐tau217 and p‐tau217/Aβ42 concentrations demonstrated robust diagnostic performance in a heterogeneous clinical cohort; interpretation requires consideration of kidney function. Highlights Plasma phosphorylated tau217 (p‐tau217) reliably identified clinic patients with Alzheimer's disease. A two‐cutpoint strategy yielded definitive results in 86% of patients. Integration of plasma amyloid beta (Aβ; p‐tau217/Aβ42) minimally improved diagnostic performance. Plasma p‐tau217 levels were increased in patients with kidney dysfunction.

AbstractBackgroundPatients with rapid progressive Alzheimer disease and related dementias (rpAD/ADRD) develop dementia within 1 year or incapacitation within 2 years of symptom onset. We previously showed that selected CSF biomarkers of neuronal injury (NfL, VILIP‐1), AD neuropathology (p‐tau181), and neuroinflammation (GFAP, MCP‐1, sTREM2) measured at presentation associated with etiologic diagnoses and reliably differentiated patients with treatment‐responsive causes of rapid progressive dementia. However, no differences were identified between CSF biomarkers in patients with rapid and typical progressive forms of AD/ADRD, leaving key questions unanswered concerning the mechanisms that drive rpAD/ADRD. Blood‐based biomarkers may inform the systemic factors that contribute to rpAD/ADRD, including the systemic inflammation, metabolic function, and vascular injury.MethodsBiomarkers of systemic inflammation (Eotaxin‐3, IFN‐γ, IL‐1b, IL‐2, IL‐4, IL‐6, IL‐8, IL‐10, IL‐12p70, IL‐13, TARC, TNF‐α), metabolic function (A2M, B2M, FABP‐3, FVII, I‐309, IL‐18, PPY, TNC, TPO), and vascular injury (CRP, SAA, sICAM‐1, sVCAM‐1) were measured in plasma obtained at presentation from patients with rpAD/ADRD (n=29) and age‐ and sex‐ similar participants with typical progressive AD/ADRD (n=39) enrolled in prospective studies of memory and aging at Mayo Clinic in Florida. Biomarker measures were completed at the University of North Texas Institute for Translational Research using Meso Scale Discovery multiplexed assays. Biomarker concentrations were compared between groups using univariate analyses; potential predictors (p<0.05) were further evaluated via step‐wise multivariate logistic regression.ResultsMarkers of vascular injury (SAA, CRP, sICAM‐1), metabolic function (I‐309, TPO), and systemic inflammation (Eotaxin‐3, TARC, TNF‐α) were increased in patients with rapid versus typical progressive AD/ADRD (p<0.05). Eotaxin‐3, I‐309, and SAA were independently associated with rpAD/ADRD in multivariable model after controlling for age and sex. The overall model correctly characterized 86.8% of patients, with an area under the curve of 0.864 (95%CI: 0.777‐0.950; p<0.001).ConclusionBlood‐based biomarkers of systemic inflammation, metabolic function, and vascular injury were elevated at presentation in patients with rapid vs typical AD/ADRD. These findings may provide additional insights into the mechanisms that drive rpAD/ADRD. Longitudinal measures from larger cohorts are needed to decipher the relationship between candidate biomarkers and rpAD/ADRD.

AbstractBackgroundThe prevalence of dementia in populations that are underrepresented in research is projected to increase with population aging. Latino and Black individuals, the largest underrepresented populations in the US, experience a higher dementia burden than non‐Hispanic White individuals, which is not explained by ethnoracial biological factors. Disparities in structural and social determinants of health may contribute to the preponderance of medical conditions known to increase dementia risk, including potentially modifiable factors in Latino and Black communities. To assess the scope of this problem, we measured the frequency of common modifiable dementia risk factors in community‐dwelling, cognitively normal, Latino and Black adults.MethodCognitively normal community‐dwelling Latino and Black adults, ≥45‐years‐old, were enrolled within our longitudinal study of memory and aging at Mayo Clinic in Florida (Jacksonville, FL) and completed a baseline assessment between 3/2022 and 10/2023. Demographics, and self‐reported race/ethnicity and history of dementia risk factors were recorded. Dementia risk factors were objectively sampled through clinical interview (depression: Geriatric Depression Scale ≥5), examination (hypertension: BP >130/80 mmHg; obesity: BMI≥30), and serum analyses (hyperlipidemia: total cholesterol<200mg/dL, HDL>50mg/dL, LDL<100mg/dL, Triglycerides<150mg/dL; diabetes: HbA1C >5.6%, vitamin B12 deficiency: <350 ng/dL).Result86 participants (43 Latino, 43 Black), 65.8 (8.8) years‐old, female (62.8%), with 16 (2.4) years of education were assessed. Dementia risk factors were frequent in Latino and Black participants, including hypertension (63%, 90%; p = 0.005), hyperlipidemia (93%, 89%; p = 0.702), obesity (33%, 44%; p = 0.370), diabetes (60%, 47%; p = 0.370), vitamin B12 deficiency (21%, 21%; p = 0.989), and depression (5%, 24%; p = 0.781). These risk factors were unrecognized or suboptimally managed in a substantial proportion of Latino and Black participants: hypertension (56%, 73%; p = 0.170), hyperlipidemia (80%, 73%; p = 0.591), diabetes (57%, 47%; p = 0.502), vitamin B12 deficiency (21%, 21%; p = 0.789), and depression (5%, 3%; p>0.99).ConclusionPotentially modifiable dementia risk factors were detected in the majority of community‐dwelling Latino and Black cognitively normal older‐adults and were frequently unrecognized or suboptimally managed. Proactive screening for known dementia risk factors may provide opportunities for targeted interventions to improve brain health and decrease dementia disparities in underrepresented populations.