Autobiographical Memory and the Default Mode Network in Mild Cognitive Impairment
Degree GrantorUniversity of Canterbury
Degree NameMaster of Science
Individuals with mild cognitive impairment (MCI) show variable impairment in autobiographical memory function, source memory function and reduced integrity in the brain’s default mode network (DMN). There is overlap between the DMN, such as the medial posterior cortical hub, and brain regions that are active when participants recall autobiographical memories. To assess the association between autobiographical memory and the DMN, 14 MCI and eleven age and education-matched healthy control participants were assessed using the autobiographical memory interview (AMI) and underwent resting state fMRI scans. The same participants underwent a test of source memory which assessed both recognition and source memory. The MCI group showed significantly increased semantic as well episodic memory impairments using the AMI, evident across the lifespan for episodic memory but not for childhood semantic memory. Significantly poorer DMN connectivity, using a goodness of fit index (GOF) of the DMN template, was evident in the MCI group. MCI participants showed poorer performance on both recognition and source memory relative to HC participants. A modest association between AMI semantic memory (r=0.4) scores, but not episodic memory scores (r=0.09), and DMN connectivity was found in these participants. For future study the predictive value of MR imaging in the DMN of MCI participants should be explored.