Differential item functioning of the Geriatric Depression Scale‐short form in the NACC dataset

The Geriatric Depression Scale - Short Form (GDS-SF) showed differential item functioning (DIF) in 13 of 15 items across demographic and cognitive groups. Only two items-hopelessness and worthlessness-were invariant across all groups. Cognitive status (Clinical Dementia Rating [CDR]) most strongly influenced item endorsement patterns. Our study used a large, diverse sample (National Alzheimer's Coordinating Center Uniform Data Set [NACC UDS]) and robust DIF analytic methods. Findings highlight both reliable and problematic GDS-SF items for older adults.