The Quick Dementia Rating System and Its Relationship to Biomarkers of Alzheimer's Disease and Neuropsychological Performance.

INTRODUCTION: The Quick Dementia Rating System (QDRS) is a brief, patient-reported dementia staging tool that has approximated scores on the Clinical Dementia Rating Scale in patients with Alzheimer's disease (AD). However, no studies have examined its relationship with AD-related biomarkers. METHODS: One-hundred twenty-one older adults (intact, amnestic mild cognitive impairment, mild AD) completed the QDRS, and three biomarkers (amyloid deposition via positron emission tomography, hippocampal volume via magnetic resonance imaging, and apolipoprotein [APOE] ε4 status). RESULTS: The Total score on the QDRS was statistically significantly related to all three biomarkers (after controlling for age, education, sex, and race), with greater levels of dementia severity being associated with greater amyloid deposition, smaller hippocampi, and having copies of APOE ε4 allele. DISCUSSION: In participants across the cognitive spectrum, the QDRS showed modest relationships with amyloid deposition, hippocampal volumes, and APOE status. Therefore, the QDRS may offer a cost-effective screening method for clinical trials in AD.