[Digit series and Knox cubes as concentration tests for elderly subjects]

Area of Science:

• Neuropsychology
• Geriatric Psychology
• Psychometrics

Context:

• Assessing cognitive function in the elderly is crucial for timely diagnosis and intervention.
• The Digit Span test (DS) and Knox Cube test (KCT) are commonly used tools for evaluating memory and executive functions.
• Understanding the psychometric properties of these tests in older adults is essential for their accurate clinical application.

Purpose:

• To evaluate the psychometric properties of the Digit Span test and the Knox Cube test in a geriatric population.
• To determine the reliability and validity of these tests for clinical assessment of cognitive abilities in the elderly.
• To explore the utility of DS and KCT in differentiating cognitive performance among older adults.

Summary:

• The study examined 100 elderly residents (aged 68-94) using the Digit Span (DS) and Knox Cube (KCT) tests.
• Digit Span administration with three trials per sequence length demonstrated high reliability and minimized floor effects, allowing separate interpretation of Forward and Backward conditions.
• The Knox Cube test exhibited low internal consistency, limiting its ability to reliably differentiate among normal subjects, though it may still aid in impairment detection. Regression equations were developed to correct Forward Digit Span scores for education level and to compare Backward Digit Span and Knox Cubes scores with Forward Digit Span.

Impact:

• Provides evidence for the reliable use of the Digit Span test in assessing elderly cognitive function.
• Highlights the limitations of the Knox Cube test's internal consistency while acknowledging its potential role in identifying cognitive deficits.
• Offers practical tools (regression equations) for refining the interpretation of DS and KCT scores in older adults, considering educational background.