Background: Prospective memory (PM), the ability to execute a previously formed intention given the proper circumstance, has been proven to be vulnerable to Alzheimer's disease. Previous studies have indicated the involvement of the frontoparietal networks; however, it is proposed that PM may also be associated with other neural substrates that support stimulus-dependent spontaneous cognition.
Objective: The present study aimed to examine the hypothesis that PM deficit in Alzheimer's disease is related to altered functional connectivity (FC) within the default mode network (DMN).
Methods: Thirty-four patients with very mild or mild dementia (17 with Alzheimer's disease and 17 with subcortical ischemic vascular disease) and 22 cognitively-normal participants aged above 60 received a computerized PM task and resting-state functional magnetic resonance imaging study. Seed-based functional connectivity analysis was performed at group level within the DMN.
Results: We found that the dementia groups showed worse PM performance and altered FC within the DMN as compared to the normal aging individuals. The FC between the medial prefrontal cortices and precuneus/posterior cingulate cortex was significantly correlated with PM in normal aging, while the FC between the right precuneus and bilateral inferior parietal lobules was correlated with PM in patients with Alzheimer's disease.
Conclusion: These findings support a potential role for the DMN in PM, and corroborate that PM deficit in Alzheimer's disease was associated with altered FC within the posterior hubs of the DMN, with spatial patterning different from normal aging.
Keywords: Alzheimer’s disease; cerebral small vessel disease; default mode network; memory for intention; prospective memory.