The Five Digits Test in the assessment of older adults with low formal education: construct validity and reliability in a Brazilian clinical sample

Abstract Introduction In the assessment of older adults with very low formal education, typical tests of selective attention and inhibitory control are biased by reading abilities. In this sense, we aim to assess the psychometric characteristics of the Five Digits Test (FDT), a numerical Stroop paradigm, in older adults without cognitive disorders, with mild cognitive impairment, and with dementia. Methods We assessed 211 Brazilian older adults with low formal education using the FDT and other cognitive measures. Construct validity and reliability were assessed by correlations and internal consistency. Results The FDT test had weak correlations with crystalized intelligence tests and moderate-high correlations with fluid intelligence measures and tests of global cognitive status and executive functions. The split-half coefficient of reliability showed high internal consistency (>0.900). Conclusion Together, the results suggest that the FDT is a valid and reliable measure for the assessment of processing speed and executive functions in older adults with low formal education.