Frequent Assessments May Obscure Cognitive Decline

Effects of an initial testing experience on the level of cognitive performance at a 2nd occasion are well documented. However, less is known about the effects of additional testing experiences beyond the 1st on the amount of cognitive change over a specified interval. This issue was investigated in a moderately large sample of adults between 18 and 95 years of age who performed a battery of cognitive tests either 2 or 3 times at variable intervals between each assessment. Multiple regression analyses were used to examine effects of the number of assessments on change while controlling the length of the interval between the 1st and last assessments. Change in each of 5 cognitive domains was less negative when there was an intervening assessment. To illustrate, for adults between 65 and 95 years of age, the estimated change from a 1st to a 2nd assessment across an average interval of 3.9 years was -.25 standard deviation units (p < .01), but it was only -.06 standard deviation units, and not significantly different from 0, when an intervening assessment occurred during the interval. These results indicate that cognitive change may not be detected when individuals are assessed frequently with relatively short intervals between the assessments.