Decreased hippocampal-prefrontal functional connectivity predicts episodic memory in Alzheimer’s disease
Eun Hyun Seo1, Jinsick Park2, Mina Heo3, IL Han Choo4; 1Premedical science, College of Medicine, Chosun University, Gwangju, Korea, 2Hanyang University, Seoul, Republic of Korea, 3Center for Development of BioMedical Technology, Chosun University Hospital, Gwangju, Korea, 4School of Medicine, Chosun University Hospital, Gwangju, Korea
Background: Alzheimer’s disease (AD) is characterized by progressive cognitive decline including memory impairment. Hippocampal-prefrontal functional connectivity (HPFC) is crucial for episodic memory process. However, the relationship between them remains unclear in AD spectrum. Therefore, this study investigated the relationship between HPFC and episodic memory in cognitively normal (CN) elderly and individuals with mild cognitive impairment (MCI) and AD. Methods: The resting-state functional and structural MRI raw data, clinical and neuropsychological data were downloaded from the Alzheimer’s Disease Neuroimaging Initiative database. BOLD time course was extracted from hippocampus and medial prefrontal region after preprocessing. Correlation analysis between these two was performed. The correlation coefficient was defined as HPFC index. Multiple linear regression was conducted to examine the ability of HPFC to predict memory. In the final analysis, 58 CN, 48 MCI, and 28 AD were included. Results: Memory score was significantly different among the CN, MCI, and AD group, whereas there was no significant group-difference in HPFC index. Multiple linear regression model revealed that left HPFC was significantly predicted memory score in total group. In subgroup analysis, AD group showed significant associations between bilateral HPFC index and memory score (R2= 0.239, p=0.045 for left HPFC, R2=0.338, p=0.007 for right HPFC). However, CN and MCI showed no significant associations between them. Conclusions: Our findings indicate that decreased intrinsic HPFC can predict episodic memory in AD. Given that hippocampus and medial prefrontal area are main nodes of default mode network (DMN), disrupted DMN may related to poor episodic memory performance in AD spectrum.
Topic Area: LONG-TERM MEMORY: Development & aging