Combining blood biomarkers and the German version of the Dementia Screening Questionnaire for Individuals with Intellectual Disabilities (DSQIID‐G) for diagnosing cognitive decline in Down syndrome

Wagemann, Olivia; Götz, Charlotte; Wlasich, Elisabeth; Sandkühler, Katja; Prix, Catharina; Stockbauer, Anna; Marth, Lena; Jäck, Alexander; Halbgebauer, Steffen; Tumani, Hayrettin; Höglinger, Günter U.; Levin, Johannes; Nübling, Georg (2026): Combining blood biomarkers and the German version of the Dementia Screening Questionnaire for Individuals with Intellectual Disabilities (DSQIID‐G) for diagnosing cognitive decline in Down syndrome. Alzheimer's & Dementia, 22 (3): e71296. ISSN 1552-5260

Abstract

INTRODUCTION:
Individuals with Down syndrome (DS) are at risk for Alzheimer's disease (AD). However, diagnosis remains challenging due to variability of intellectual ability and symptom presentation. To investigate whether serum AD biomarkers enhance accuracy of the German version of the Dementia Screening Questionnaire for Individuals with Intellectual Disabilities (DSQIID-G), we combined test scores with neurofilament light chain (NfL) and glial fibrillary acidic protein (GFAP) levels.

METHODS:
Seventy-eight DS individuals (49% female) completed the DSQIID-G; previous cohort data were added for a pooled sample (n = 164, 47% female). Serum NfL and GFAP were assessed using the automated microfluid Ella system.

RESULTS:
Combining the DSQIID-G with NfL or GFAP resulted in improved accuracy in every diagnostic subgroup. The Youden index in the pooled samples yielded a cut-off score at 6.5.

DISCUSSION:
The DSQIID-G is a robust screening tool and its combination with AD blood biomarkers aids earlier identification of individuals requiring further diagnostics for DS-associated AD.

Highlights:
The German version of the Dementia Screening Questionnaire for Individuals with Intellectual Disabilities (DSQIID-G) is a reliable screening tool for suspected cognitive decline in adults with Down syndrome (DS).
A cut-off score of 6.5 optimizes DSQIID-G performance for a sensitivity > 80%.
Adding neurofilament light chain or glial fibrillary acidic protein to the DSQIID-G further improves discriminatory power for DS-associated Alzheimer's disease.
The combined screening–biomarker approach holds promise for early detection of cognitive decline in DS.

• Doc-Type: Article (LMU Hospital)
• Organisational unit (Faculties): 07 Medicine > Munich Cluster for Systems Neurology (SyNergy); 07 Medicine > Medical Center of the University of Munich > Neurosurgical Clinic and Polyclinic
• DFG subject classification of scientific disciplines: Life sciences
• DFG: Funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) - 491502892
• DFG: Funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) - 390857198