Adult lifespan normative data (18-92 years) for executive function tests; the Stroop colour word test, COWAT and...

The neuropsychological assessment of executive functions is an important part of the diagnostic process for many neurological diseases and for predicting the ability of neurological patients to function independently. Unfortunately, for the majority of commonly used executive function tests there is a paucity of updated normative data, particularly for older adults. This complicates the process of a clinically meaningful assessment. To help address this, we provide normative data for three well-validated tests of executive functions, the Stroop Colour/Word Test, the Controlled Oral Word Association Test and the Hayling Sentence Completion Test, alongside scores from an estimate of general intellectual ability. These tests are sensitive to frontal lobe damage and provide clinicians with information about possible focal damage to the left and right frontal lobes. Percentiles are presented for five age cohorts across the adult lifespan (18-92 years). A regression equation with age and predicted full-scale IQ also allows for the categorisation of normal and defective performance on the Stroop and Hayling tests. Given the increasing proportion of older adults requiring neuropsychological assessment, we investigated separately two groups in the older adult range: 65-79 years and 80-92 years. We found a decline in performance for older adults on all three tests. This decline was more marked amongst lower scoring older adults. We did not find a significant relationship between sex and performance on any of the three tests. The findings are discussed in the light of the cognitive reserve theory of ageing.