Alzheimer?s disease and related dementias (ADRD), a leading cause of disability among older adults, has become a critical public health concern. The clock-drawing test (CDT), which measures multiple aspects of cognitive function including comprehension, visual spatial abilities, executive function and memory, has been widely used as a screening tool to detect dementia in clinical research, epidemiologic studies, and panel surveys. The CDT asks subjects to draw a clock, typically with hands showing ten after 11, and then assigns either a binary (e.g. normal vs. abnormal) or ordinal (e.g. 0 to 5) score. An important limitation in large-scale studies is that the CDT requires manual coding, which could result in biases if coders interpret and implement coding rules in different ways.
Several small-scale studies have explored the use of machine learning methods to automate CDT coding. Such studies, which have had limited success with ordinal coding, have used methods that are not designed specifically for complex image classification and are less effective than deep learning neural networks (DLNN), a new and promising area of machine learning. More recently, machine learning methods have been applied to digital CDT (dCDT), a form of CDT that uses a digital pen and tablet. Despite some promising results on small-scale data, thus far dCDT studies have only attempted to code binary categories.
The proposed study will develop advanced DLNN models to create and evaluate an intelligent CDT Clock Scoring system ? CloSco ? that will automatically code CDT images. We will use a large, publicly available repository of CDT images from the 2011-2019 National Health and Aging Trends Study (NHATS), a panel study of Medicare beneficiaries ages 65 and older funded by the National Institute on Aging. Specifically, we will: 1) Develop an automated CDT-coding system for both ordinal and continuous scores; 2) Evaluate the performance of the CloSco system and investigate the value of continuous CDT scoring for dementia classification and longitudinal CDT models; and 3) Prepare and disseminate NHATS public-use files and documentation with ordinal and continuous CDT codes assigned using CloSco along with the CloSco DLNN program. If successful, the DLNN programs may offer a model for automating coding of other widely available drawing tests used to evaluate a variety of cognitive functions.
Health and Human Services, Department of-National Institutes of Health
09/15/2021 to 08/31/2023