Precuneus degeneration in nondemented elderly individuals with APOE ɛ4: Evidence from structural and functional MRI analyses

Abstract

Neurodegenerative diseases such as Alzheimer's disease (AD) have been recognized to exhibit disease-specific brain vulnerability patterns. Apolipoprotein E (APOE) ɛ4 allele imparts a high genetic risk of developing AD. Whether the APOE ɛ4 allele damages the brain when cognitive functions are still intact is important to understand, especially for possible early detection and intervention. This study aimed to examine the selective degeneration pattern associated with the APOE ɛ4 allele in the brains of cognitively normal elderly subjects. We enrolled 35 cognitively healthy ɛ4 carriers and 40 non-carriers (53 to 81 years old) to evaluate group differences in cortical thickness and brain activation during a memory-encoding task. We also assessed the functional connectivity of the brain regions with both structural and functional damages. The results from the neuropsychological tests showed that the performances of ɛ4 carriers and non-carriers were comparable. Primarily, we found that the precuneus exhibited thinner cortical thickness and decreased deactivation during memory encoding. Furthermore, the connectivity analyses show that carriers exhibited damaged connectivity of the precuneus to several regions in the default mode network and the attention/executive control network. Our study reveals the degeneration pattern of the ɛ4 allele, which could be used as a potential biomarker for early detection for possible interventions and treatments. Hum Brain Mapp 38:271-282, 2017. © 2016 Wiley Periodicals, Inc.

Alterations in structural rich-club connectivity of the precuneus are associated with depressive symptoms among individuals with subjective memory complaints

“…This finding may be partly consistent with other previous studies, which suggested that the hippocampus may be affected as depression progresses rather than in the subclinical stage of depression (Hayakawa et al, 2013;Taki et al, 2005). In addition, previous studies have reported that asymptomatic APOE ε4 carriers in healthy elderly showed structural changes in the precuneus exclusively, and not in the hippocampus (Brown et al, 2011;Chen et al, 2017). The current study may support that the alteration in connectivity strength of the hippocampus is progressionspecific in the case of SMCs and depression.…”

Current understanding of magnetic resonance imaging biomarkers and memory in Alzheimer's disease

“… Erk, et al 2011 [48] 19 subjective memory impairment, 20 CNC Face-profession association ROI (HC, DLPFC) Reduced right HC activation, increased right DLPFC activation in subjective memory impairment group. Chen, et al 2017 [49] 35 APOE ε4 carrier, 40 noncarrier CNC Picture encoding Seed ROI based on group cortical morphology differences and DMN/cortical thickness Reduced precuneus deactivation, reduced postcentral, precentral, inferior occipital gyri, inferior parietal lobule activation in APOE ε4 carriers. MCI Johnson, et al 2006 [50] 14 MCI, 14 CNC Picture encoding Reference group activation Reduced R HC head and body, L lateral frontal, R inferior temporal lobe activation in MCI during novel pictures.…”

Brain Functional Differences in Drug‐Naive Major Depression with Anxiety Patients of Different Traditional Chinese Medicine Syndrome Patterns: A Resting‐State fMRI Study

“…e precuneus also assists other brain regions in performing functions such as information processing, especially in regards to emotion regulation [59,60]. Furthermore, the precuneus is a major hub of brain organization and a central node of DMN [61,62].…”