Development and validation of the Ascertain Dementia 8 (AD8) Thai version

BACKGROUND: The Ascertain Dementia 8 (AD8) is a brief informant‐based questionnaire which reliably distinguishes patients with neurocognitive disorder (NCD) and normal cognition. Our objective was to translate the AD8 into Thai and test its validity as a potentially useful measure to detect patients with the mild stage of major NCD due to Alzheimer disease (major NCD‐AD). METHODS: Evaluations of 144 informant–patient dyads were made. Participants were patients who attended the memory clinic at Ramathibodi Hospital and non‐patient volunteers. The AD8‐Thai version was administered separately from doctor's interviews and neuropsychological assessments. Diagnostic workups included a complete medical history, physical and neurological examinations, neuropsychological testing, the Clinical Dementia Rating Scale‐Sum of Boxes (CDR‐SOB), Montreal Cognitive Assessment (MoCA), blood tests and brain imaging, preferably with magnetic resonance imaging. All researchers were blinded to the AD8 results. RESULTS: An AD8 score ≥3 had a sensitivity of 95.5%, a specificity of 89.5%, a positive predictive value of 84%, and a negative predictive value of 97.1% for screening major NCD‐AD and those with normal cognition. A subgroup analysis with participants aged ≥65 years and with ≥12 years of education revealed comparable ability to the whole group. AD8 scores had a moderate negative relationship with MoCA scores (r = −0.470) and a strong positive relationship with CDR‐SOB scores (r = 0.547). The performance of AD8 scores in differentiating mild NCD from normal cognition was not as good as for major NCD‐AD. CONCLUSIONS: AD8‐Thai version is an acceptable screening tool for major NCD‐AD. For patients aged 65 years or older, with at least 12 years of education, and with cognitive complaints in memory clinic, an AD8‐Thai score of 3 or more would be sufficient to work on major NCD diagnosis. The performance of the AD8‐Thai in mild NCD needs further investigation.