RT Journal Article
SR Electronic
T1 Semantic Fluency Predicts Six-Year Progression to Mild Cognitive Impairment in Middle-Aged Men
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 659417
DO 10.1101/659417
A1 Daniel E. Gustavson
A1 Jeremy A. Elman
A1 Matthew S. Panizzon
A1 Carol E. Franz
A1 Jordan Zuber
A1 Mark Sanderson-Cimino
A1 Chandra A. Reynolds
A1 Kristen C. Jacobson
A1 Hong Xian
A1 Amy J. Jak
A1 Rosemary Toomey
A1 Michael J. Lyons
A1 William S. Kremen
YR 2019
UL http://biorxiv.org/content/early/2019/06/04/659417.abstract
AB Objective Test the hypothesis that individual differences in episodic memory and verbal fluency in cognitively normal middle-aged adults will predict progression to amnestic MCI after 6 years.Method 1484 male twins, 842 of whom were cognitively normal at wave 1 completed measures of episodic memory and verbal fluency at up to 2 time-points (mean age 56 and 62 years).Results In the subgroup of 842, poor episodic memory predicted progression to both amnestic MCI (OR=4.42, 95% CI [2.44, 10.60]) and non-amnestic MCI (OR=1.92, 95% CI [1.32, 3.44]). Poor semantic verbal fluency also independently predicted progression to amnestic MCI (OR=1.86, 95% CI [1.12, 3.52]). In the full sample, a semantic-specific fluency latent variable at wave 1 (which controls for phonemic fluency) predicted change in episodic memory at wave 2 (β=.13), but not vice-versa (β=.04). Associations between episodic memory and verbal fluency factors were primarily explained by genetic, rather than environmental, correlations.Conclusions These findings emphasize the utility of memory and fluency measures in early identification of AD risk. Among individuals who were cognitively normal at wave 1, episodic memory moderately-to-strongly predicted progression to MCI at average age 62, emphasizing the fact that there is still meaningful variability even among cognitively normal individuals. Episodic memory, which is typically a primary focus for AD risk, declined earlier and more quickly than fluency. However, semantic fluency at average age 56 predicted of 6-year change in memory as well as progression to amnestic MCI even after accounting for baseline memory performance.