Temporal Sequence Learning in Healthy Aging and Amnestic Mild Cognitive Impairment

Abstract

Background/Study Context: Temporal sequence learning is a critical aspect of episodic memory that may be dependent on the temporal and frontal lobes. Because amnestic mild cognitive impairment (aMCI) and normal aging may result in changes within the temporal and frontal lobes, the present study investigated temporal sequence learning in patients with aMCI, cognitively normal older adults, and young adults.

Methods: On each trial of a temporal sequence task, circles appeared one at a time at the end of each arm of a computerized radial eight-arm maze. Participants were asked to reproduce the temporal sequence by placing numbered circles (1 to 8) on the arms of the eight-arm maze. Participants were presented with the same fixed sequence on each trial until the sequence was replicated without any errors, or until 15 trials were presented.

Results: Individuals with aMCI required significantly more trials to learn the temporal sequence compared with older adults (p < .05). Older adults required significantly more trials to learn the sequence than young adults (p < .05). Older adults and individuals with aMCI committed significantly more Trial 1 errors (p < .05) than young adults; however, there were no significant differences between the aMCI and older adult groups on Trial 1.

Conclusion: The results suggest that temporal sequence learning deficits are detectable in aMCI. These deficits may disrupt a number of cognitive processes, such as episodic memory, that are important for the execution of daily activities. The results suggest that although temporal sequence learning declines with normal aging, this decline is greater in individuals who have a diagnosis of aMCI and are at higher risk for developing Alzheimer's disease.

Acknowledgments

This research was supported by a National Institutes of Health grant (no. AG034202) from the National Institute on Aging awarded to Paul E. Gilbert. The authors thank Genevive Brusati for her assistance with data collection. The authors also thank all of the participants in this study for their contributions.

Notes

Note. Raw scores are reported. DRS = Dementia Rating Scale; GDS = Geriatric Depression Screening Scale; CVLT = California Verbal Learning Test.

¹A potentially interesting analysis would involve a comparison between learning trials on the CVLT and the temporal sequence task. However, the comparison cannot be accomplished due to the discontinuation rule implemented on the temporal sequence task. As a result of the discontinuation rule, some participants completed the temporal sequence task in the first few trials, whereas others required more trials to complete the task. This is in contrast to the CVLT, in which participants complete five learning trials regardless of the number of words recalled on each trial.