# Cognitive Impairment in Sjögren's Disease: Unmasking Alzheimer's Through CSF Biomarkers. A Case Report

## TL;DR

A patient with Sjögren's disease showed Alzheimer's-like brain changes, highlighting the need to consider dementia in autoimmune disease patients.

## Contribution

Demonstrates the diagnostic value of CSF biomarkers in distinguishing Alzheimer's from autoimmune-related cognitive decline in Sjögren's disease.

## Key findings

- A patient with Sjögren's disease had Alzheimer's-like CSF biomarkers despite mild brain imaging changes.
- Cognitive decline in autoimmune patients may be due to neurodegeneration rather than autoimmune mechanisms.
- Biomarker testing can prevent misdiagnosis of Alzheimer's in patients with autoimmune conditions.

## Abstract

Cognitive impairment in Sjögren's disease (SD) is typically attributed to autoimmune mechanisms or small vessel disease. However, its overlap with neurodegenerative pathology remains poorly understood. We report a 74‐year‐old woman with clinically diagnosed SD presenting with progressive memory decline. She demonstrated severe amnestic deficits on neuropsychological testing and had a cerebrospinal fluid (CSF) profile consistent with Alzheimer's disease (AD), including low Aβ1–42 and elevated total tau and phosphorylated tau. MRI revealed only mild small vessel disease. This case highlights the diagnostic importance of CSF biomarkers in distinguishing neurodegenerative from autoimmune cognitive syndromes. Though the overlap may be coincidental, it raises the question of whether systemic inflammation in SD could contribute to AD pathogenesis. This case illustrates how neurodegenerative disease may be overlooked in patients with autoimmune conditions. In individuals with SD and persistent amnestic symptoms, biomarker testing can help distinguish Alzheimer's pathology from autoimmune cognitive syndromes and guide more accurate diagnosis and care.

In patients with clinically diagnosed Sjögren's disease and progressive cognitive decline, Alzheimer's pathology should be actively considered. CSF biomarker testing can help avoid diagnostic overshadowing by autoimmune mechanisms and guide more accurate diagnosis and care.