Longitudinal Study of Performance on the Ruff Figural Fluency Test in Persons Aged 35 Years or Older

Abstract

The Ruff Figural Fluency Test (RFFT) is a cognitive test to measure executive function. Longitudinal studies have shown that repeated testing improves performance on the RFFT. Such a practice effect may hinder the interpretation of test results in a clinical setting. Therefore, we investigated the longitudinal performance on the RFFT in persons aged 35–82 years. Performance on the RFFT was measured three times over an average follow-up period of six years in 2,515 participants of the Prevention of REnal and Vascular ENd-stage Disease (PREVEND) study in Groningen, the Netherlands: 53% men; mean age (SD), 53 (10) years. The effect of consecutive measurements on performance on the RFFT was investigated with linear multilevel regression models that also included age, gender, educational level and the interaction term consecutive measurement number x age as independent variables. It was found that the mean (SD) number of unique designs on the RFFT increased from 73 (26) at the first measurement to 79 (27) at the second measurement and to 83 (26) at the third measurement (p<0.001). However, the increase per consecutive measurement number was negatively associated with age and decreased with 0.23 per one-year increment of age (p<0.001). The increase per consecutive measurement number was not dependent on educational level. Similar results were found for the median (IQR) number of perseverative errors which showed a small but statistically significant increase with repeating testing: 7 (3–13) at the first measurement, 7 (4–14) at the second measurement and 8 (4–15) at the third measurement (p trend = 0.002). In conclusion, the performance on the RFFT improved by repeating the test over an average follow-up period of three to six years. This practice effect was the largest in young adults and not dependent on educational level.

A Computerized Test of Design Fluency

“…Age, education, and computer-use correlated significantly with the number of unique patterns produced. As in previous studies [ 3 , 6 , 9 , 11 ], there was a substantial decline in unique pattern production with age [r = -0.42, t(178) = - 6.17, p < 0.0001]. Years of education was only marginally correlated with unique pattern production [r = 0.14, t(178) = 1.89, p < 0.07].…”

“…For example, the mean score of participants in the 5-PT study of Fernandez et al [ 5 ] was nearly one standard deviation below the mean score of participants in the study of Cattelani et al [ 4 ], despite relatively comparable ages (47.8 vs. 37.2 years) and identical levels of education (13.1 years). Similarly, Izaks et al [ 10 ] and van Eersel et al [ 11 ] obtained mean scores with the RFFT that were approximately 0.8 standard deviations below the norms of Ruff et al [ 9 ]. Izaks et al [ 10 ] presented the unique pattern scores stratified into two age ranges and three levels of education from both studies.…”

“…In contrast to the 5-PT, where any repetition over the entire 5-min test is categorized as a perseverative error, unique pattern scores and repetitions are separately tallied for each 1-min test segment in the RFFT. As a result, the average rate of pattern production per minute is higher on the RFFT than the 5-PT [ 10 , 11 ], and repeated patterns occur less frequently (see Table 1 ). Indeed, young college graduates produced an average of 114 patterns with 7 repetitions during the five-minute test [ 9 , 12 ].…”

Classification of user performance in the Ruff Figural Fluency Test based on eye-tracking features

“…Fluency itself is understood as the ability to apply some strategies to generate nonverbal responses maximising response efficiency and simultaneously minimising response repetition [2]. Such effective repetition needs processes including planning, inhibition, cognitive flexibility, decision-making and self-monitoring [3,4]. The test proved to be reliable, and the data support the thesis that the performance depended not on sex, but on age and education [5].…”

“…It is more and more often included in cognitive and neuropsychological test batteries [4]. The RFFT proved to be sensitive to the first changes in cognitive functioning in the domain of executive function [3]. Furthermore, the RFFT is useful in searching for early changes in cognitive function among young and middle-aged persons [12].…”