Episodic future thinking and intertemporal decision making in at-risk state of Alzheimer's Disease
Final Report Abstract
The major findings of this project are the following aspects. First, we have found that the SCD subjects, who are at risk for AD dementia, were not different from healthy controls in the quality of the imagined personal episodic events. Second, our fMRI results showed that the neuronal correlates of the episodic future imagination were different between two groups, in which the SCD subjects show decreased medial frontal pole activation during the imagination compared to the healthy control subjects, indicating less sustained attention during the elaboration of the future imagination. Our third goal is to investigate the modulation effect of the episodic future imagination on the intertemporal decision as well as the neuronal substrate of this process in persons at risk for AD. We have found that, individuals with SCD exhibit reduced preference for the future oriented choices during the intertemporal decision task than the control subjects. The episodic future imagination condition increased the future oriented choices during the intertemporal decision task in the control group. However, this modulation effect was not observed in the SCD group. Our fMRI results showed increased activities in the right insular cortex under the episodic future imagination condition in the control group, but not in the SCD group, indicating that the control subjects more strongly engaged the insular cortex for the switching between the episodic imagination task (default mode network) and the intertemporal decision task (executive network) . Furthermore, higher activities associated with subjective value in the ACC were found during the episodic future imagination condition than the control condition in the control group, indicating that elderly healthy control subjects have the same pattern of the brain activity associated with the modulation effect as the previous findings in the young healthy subjects. However, this pattern of the brain activity was not observed in the SCD group in the current study, indicating the lack of the neuronal modulation effect of the episodic future imagination in the SCD subjects. The surprises in the course of the project are the followings: first, patients with MCI were not able to carry out the fMRI experiment paradigm due to limited cognitive capacity. Thus, we were not able to recruit the MCI group for the fMRI study in the current project. Second, the instruction of the original version of the fMRI experiment was difficult for elderly subjects to follow. Thus, we had to spend extra time for the purpose of modifying and piloting the experimental paradigm. Third, we did not expect the decreased intertemporal decision ability in SCD subjects per se. This additional result is interesting for the further uses of this task in screening the risk persons for AD dementia. No other surprises in the results were observed.
Publications
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(2016). Abnormal functional connectivity within default mode network in persons with subjective cognitive decline: self-reflection of own memory deficits? – group ICA with spatial constraints. Alzheimer Association International Conference in Toronto on 23 July 2016
Hu X, Huang B, Schleupner M, Weber B, Jessen F
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(2017). A reduction in delay discounting by using episodic future imagination and the association with episodic memory capacity. Front Hum Neurosci. 10:663
Hu X, Kleinschmidt H, Martin JA, Han Y, Thelen M, Meiberth D, Jessen F, Weber B
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(2017). Reduced future oriented decision making in individuals with subjective cognitive decline: A functional MRI study. Alzheimers Dement (Amst). 6:222-231
Hu X, Uhle F, Fliessbach K, Wagner M, Han Y, Weber B, Jessen F
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(2017). The phenomenology and the neuronal correlates of episodic future imagination in persons with subjective cognitive decline and healthy controls. Alzheimer Association International Conference in London on 19 July 2017
Hu X, Schafmeyer FF, Schleupner M, Ludwig F, Sannemann L, Weber B, Jessen F
