Normative performance on the executive clock drawing task in a multi-ethnic bilingual cohort: a project FRONTIER study.

BACKGROUND: The executive clock drawing task (CLOX) test is a neuropsychological measure intended to aid in the assessment and detection of dementia in older populations. Few studies have provided normative data for this measure, with even less research available regarding the impact of sociodemographic factors on test scores. This study presents normative data for the CLOX in a sample of English and Spanish-speaking Hispanic and non-Hispanic Whites.
METHODS: The total sample included 445 cognitively healthy older adults seen as part of an ongoing study of rural cognitive aging, project FRONTIER. Unlike previous studies, criteria for "normality" (i.e., unimpaired) for CLOX1 and CLOX2 were based not merely on global impairment, but also on domain-specific impairment of executive functioning on the Executive Interview 25-item Examination and/or Trail Making Test B, or visuospatial/constructional impairment on the Line Orientation and Figure Copy subtests of the Repeatable Battery for the Assessment of Neuropsychological Status, respectively.
RESULTS: Hierarchical regression analyses revealed that CLOX1 scores require adjustment by Age across ethnicities, whereas Education and Gender are necessary stratification markers for CLOX1 performance only in non-Hispanic Whites. None of the demographic variables were valid predictors of CLOX2 performance, negating the need for such adjustments.
CONCLUSION: In addition to being the first study to provide separate normative data for CLOX performance in Hispanic and non-Hispanic White samples, the current study offers a novel approach to defining "normal" by cognitive domain. We also highlight the need to directly examine the impact of sociodemographic factors before applying normative corrections based on factors that have negligible impact on test scores.