Comparison of Cross-Sectional and Longitudinal Data on Animal Fluency in Older Adults

• Published in: Archives of clinical neuropsychology 2013-01, Vol.28 (6), p.57-58
• Main Authors: Zec, R, Kohlrus, S, Fritz, S, Robbs, R, Ala, T
• Format: Article
• Language: English
• ISSN: 0887-6177

Objective: To compare the findings from our cross-sectional and longitudinal studies on the effects of age on Animal Fluency. Method: There were 1045 "normal" older adults (age 50-89) in the cross-sectional analysis and 618, 315, 267, and 197 participants with at least 2, 4, 5, and 6 annual visits in the longitudinal study were. There were 239 subjects in whom the first and last testing were at least 6 years apart and 124 that were at least 10 years apart. Results: The magnitude of the Animal Fluency decline was considerably greater in the cross-sectional study. There was a 1.48-word decline (7.3%) when comparing the 50s and 60s age groups, a 1.40-word decline (7.5%) when comparing the 60s and 70s, and a 1.34- word decline (7.7%) when comparing the 70s and 80s. In our longitudinal study, we found no change (0.02 words, 0.1%) in the 50s age group when projected over 10 years, a small decline in the 60s (-0.78 words, 4.0%), a small decline in the 70s (-1.05 words, 5.7%), and a very small decline in the 80s age group (-0.16 words, 1.0%). Conclusion: There was a 1.65- word decline in the longitudinal study between the 50s and 80s age groups and a 4.22-word decline in the cross-sectional study. There were likely cohort effects in our cross-sectional study, whereas there likely was a selective attrition bias in our longitudinal study. Thus, an estimate of the "true" mean animal fluency decline is 2-3 words from the fifth to eighth age decade with the clearest declines in the sixth and seventh decades.