Validity of one-time assessments for identifying prodromal Alzheimer's disease in adults with Down syndrome

Introduction: New Alzheimer's disease (AD) treatments have created an urgent need for accurate early diagnosis of high-risk adults with Down syndrome (DS), distinguishing prodromal DS-AD symptoms from lifelong cognitive impairments. Often, clinicians will need to evaluate dementia status during a single assessment, and here we describe empirically supported methods effective under such circumstances. Methods: Archived data collected between 1987 and 2017 included longitudinal findings for 144 individuals maintaining cognitive stability and 126 developing prodromal DS-AD. Response operating characteristic analyses compared groups, defined by the presence/absence of prodromal DS-AD, for a single assessment. Results: Groups differed on all measures without adjusting for developmental history, 0.717 < areas under the curve < 0.859, Ps < 0.0001. The balance between sensitivity and specificity improved slightly when developmental histories were considered. Discussion: The present study demonstrated that one-time assessments can inform clinical judgments when diagnosing adults at risk for DS-AD. Knowledge of developmental history is valuable but non-essential.