Supplementary Material for: Cerebrospinal Fluid Biomarkers in Clinical Subtypes of Early-Onset Alzheimer's Disease

<b><i>Background/Aims:</i></b> Accurate diagnosis of sporadic early-onset Alzheimer's disease (EOAD) can be challenging, and cerebrospinal fluid (CSF) biomarkers may assist in this process. We compared CSF indices between three EOAD subtypes: amnestic, logopenic progressive aphasia (LPA), and posterior cortical atrophy (PCA). <b><i>Methods:</i></b> We identified 21 amnestic EOAD, 20 LPA, and 12 PCA patients with CSF data, which included amyloid β<sub>1-42</sub> (Aβ42), total tau (t-tau), phospho-tau<sub>181</sub> (p-tau), and Aβ42/t-tau index (ATI) levels. <b><i>Results:</i></b> Aβ42 and ATI levels were similar across groups, but t-tau and p-tau levels were significantly lower in PCA patients. <b><i>Conclusions:</i></b> The Aβ42 and ATI data confirm the commonality of the Aβ pathology in EOAD. The lower tau indices in PCA patients may reflect differences in the distribution of neurofibrillary tangles or rates of neurodegeneration.