Effects of Apolipoprotein Genotype on the Longitudinal Trajectory of Cognitive Processing Speed Performance in Healthy Elderly Subjects.

摘要

A decline in cognitive processing speed has been proposed to be one of the earliest signs of aging, and it has been associated with important neurobiological markers of neurodegenerative process such as apolipoprotein (APOE) &egr;4 in Alzheimer's disease. The purpose of the study is to examine the longitudinal trajectory of cognitive processing speed performance in healthy adults and its relationship to APOE genotypes. Participants were identified into one of 2 groups: APOE &egr;4 carriers and non-carriers. Furthermore, independent effects of &egr;2 (i.e., protected group) and &egr;4 (i.e., risk group) on longitudinal trajectory of cognition were examined. All participants completed neuropsychological evaluations measuring several cognitive domains at 3 time points. The time between the evaluations (1 baseline and 2 follow-up evaluations) ranged from 9 to 12 months over approximately 2 years. The relative changes in performance were compared using 2x2 repeated measures analysis of variance. The results revealed that APOE &egr;4 carriers did not differ from non-carriers in their performance trajectory on cognitive processing speed as well as language, visuospatial skills, executive functioning, and memory. However, further exploratory analyses revealed significant change in their performance trajectory between risk group (i.e., select &egr;3/&egr;4 and &egr;4/&egr;4) and protected group (i.e., &egr;2/&egr;3) on a cognitive processing speed, whereas the interaction effect of group and time was not present in other cognitive domains. The findings indicate the earliest sign of cognitive decline in relation to APOE status &egr;4 can be detected from cognitive processing measures.;Keywords: Cognitive processing speed; APOE; Longitudinal study; Healthy adults.