Retrospective investigations of practice effects on repeated neuropsychological measures of executive functioning

The present study aimed to investigate the degree to which serial testing may impact neuropsychological test scores following serial evaluation of executive function. Healthy control data were retrospectively analysed, recruited as part of a longitudinal study of cognitive impairment in amyotrophic lateral sclerosis. As part of a larger battery of tests, participants were assessed using The Brixton Spatial Anticipation Test (n = 31), Backward Digit-span (n = 22), The Stroop Colour-Word Test (n = 30) and Phonemic Fluency (n = 29). Participants completed the tests on three occasions at 6-month intervals. Results showed no statistically significant difference between any of the measures of executive function over the three time points. Further covariate analyses showed that intellectual ability was not a confounding variable when investigating practice effects, as previously reported in literature. In an Irish cohort, participants did not show statistically significant changes over time on neuropsychological tests, either positively or negatively. Although these findings should be considered exploratory due to sample size, the wide age range and the retrospective nature of analysis, the data suggests practice effects did not significantly influence the test results in this cohort when assessed at 6-month intervals. Implications relative to these findings are discussed.