ABSTRACT
Objective@#To explore the effects of ApoE epsilon4 (ApoE-ε4) alleles on cognitive function and resting-state functional MRI (rs-fMRI) in patients with amnestic mild cognitive impairment(aMCI) based on a prospective cohort study.@*Methods@#An average of 20 months of prospective observations were conducted on 16 ApoE-ε4-carriers and 24 non-carriers of aMCI. Neuropsychological assessments and rs-fMRI data were collected at both baseline and follow-up. All participants were assessed by a battery of neuropsychological tests and underwent rs-fMRI. Two core regions of the default mode network (DMN), the left posterior cingulate cortex (PCC) and the medial prefrontal cortex (mPFC), were selected as seeds to calculate the functional connectivity. Two-way repeated measures analysis of variance was used to assess the effects of ApoE genotype(ε4-carriers, nonε4-carriers), interval and the interaction between these two factors for functional connectivity extracted from changed region found by t-test.Conversion rates of dementia were compared between ApoE-ε4-carriers and nonε4-carriers at follow-up using Chi-square test. For the comparison of functional connectivity and clinical data between ApoE-ε4-carriers and nonsε4-carriers in baseline and follow-up, the normal distribution test was carried out first. If the normal distribution was fitted, the two-sample t test was used, otherwise, the Mann-Whitney rank sum test was used. Finally, the general linear model was used to assess the relationships between alterations in functional connectivity and in neuropsychological assessments as well as the interaction effect.@*Results@#(1)Significant decline in memory domains were found in ApoE-ε4-carriers as compared to non-carriers at both baseline and follow-up. The ApoE-ε4-carriers (14/16) presented a higher conversation rate than non-carriers(13/24, χ2=4.862, P=0.027) at follow-up. (2)Functional imaging analysis revealed that ApoE-ε4-carriers exhibited significantly higher functional connectivity between the left PCC and the left angular (ApoE-ε4-carriers: 0.23±0.11, non-carriers: -0.03±0.13, t=4.800, cluster size: 1 944 mm3, P=0.004), and between the left mPFC and the left angular (ApoE-ε4-carriers: 0.33±0.21, non-carriers: 0.08±0.18, t=5.040, cluster size:1 836 mm3, P=0.006) as compared to non-carriers at follow-up. We detected significant effect for the interaction interval by ApoE-ε4 on functional connectivity between the left angular and the left PCC (F=10.833, P=0.002)as well as the left mPFC (F=7.280, P=0.010). (3)The alteration of functional connectivity value between the left mPFC and the left angular in ApoE-ε4-carriers was positively correlated with the changes ofimmediate memory (r=0.692, P=0.018). The correlation was not statistically significant in ApoE-ε4-noncarriers (r=-0.198, P=0.417) and the integration effect was significant (F=8.632, P=0.006).@*Conclusions@#The ApoE-ε4 actually accelerates the deterioration of cognitive function in aMCI patients and carriers presented relatively reserved functional connectivity between the left angular and other core regions within DMN, which indicated the disruption of functional connectivity may be one of the underline mechanisms of ApoE-ε4 during AD process.
ABSTRACT
Alzheimer′s disease (AD) is an incurable disease in the field of major chronic diseases. Subjective cognitive decline (SCD) is a clinical risk factor for AD. The standardized screening and intervention in individuals with SCD are of great importance in early prevention and treatment of AD. According to the clinical criteria proposed by The characterisation of subjective cognitive decline, which was published online in Lancet Neurology, the article summarized the definition of SCD, the latest perspective of clinical standards in SCD, and the results of AD preclinical SCD research. The purpose of this work was to provide concrete guidance and recommendations for making clinical decisions in diagnosis and scientific research on SCD.
ABSTRACT
Objective:To explore the effects of ApoE epsilon4 (ApoE-ε4) alleles on cognitive function and resting-state functional MRI (rs-fMRI) in patients with amnestic mild cognitive impairment(aMCI) based on a prospective cohort study.Methods:An average of 20 months of prospective observations were conducted on 16 ApoE-ε4-carriers and 24 non-carriers of aMCI. Neuropsychological assessments and rs-fMRI data were collected at both baseline and follow-up. All participants were assessed by a battery of neuropsychological tests and underwent rs-fMRI. Two core regions of the default mode network (DMN), the left posterior cingulate cortex (PCC) and the medial prefrontal cortex (mPFC), were selected as seeds to calculate the functional connectivity. Two-way repeated measures analysis of variance was used to assess the effects of ApoE genotype(ε4-carriers, nonε4-carriers), interval and the interaction between these two factors for functional connectivity extracted from changed region found by t-test.Conversion rates of dementia were compared between ApoE-ε4-carriers and nonε4-carriers at follow-up using Chi-square test. For the comparison of functional connectivity and clinical data between ApoE-ε4-carriers and nonsε4-carriers in baseline and follow-up, the normal distribution test was carried out first. If the normal distribution was fitted, the two-sample t test was used, otherwise, the Mann-Whitney rank sum test was used. Finally, the general linear model was used to assess the relationships between alterations in functional connectivity and in neuropsychological assessments as well as the interaction effect. Results:(1)Significant decline in memory domains were found in ApoE-ε4-carriers as compared to non-carriers at both baseline and follow-up. The ApoE-ε4-carriers (14/16) presented a higher conversation rate than non-carriers(13/24, χ 2=4.862, P=0.027) at follow-up. (2)Functional imaging analysis revealed that ApoE-ε4-carriers exhibited significantly higher functional connectivity between the left PCC and the left angular (ApoE-ε4-carriers: 0.23±0.11, non-carriers: -0.03±0.13, t=4.800, cluster size: 1 944 mm 3, P=0.004), and between the left mPFC and the left angular (ApoE-ε4-carriers: 0.33±0.21, non-carriers: 0.08±0.18, t=5.040, cluster size:1 836 mm 3, P=0.006) as compared to non-carriers at follow-up. We detected significant effect for the interaction interval by ApoE-ε4 on functional connectivity between the left angular and the left PCC ( F=10.833, P=0.002)as well as the left mPFC ( F=7.280, P=0.010). (3)The alteration of functional connectivity value between the left mPFC and the left angular in ApoE-ε4-carriers was positively correlated with the changes ofimmediate memory ( r=0.692, P=0.018). The correlation was not statistically significant in ApoE-ε4-noncarriers ( r=-0.198, P=0.417) and the integration effect was significant ( F=8.632, P=0.006). Conclusions:The ApoE-ε4 actually accelerates the deterioration of cognitive function in aMCI patients and carriers presented relatively reserved functional connectivity between the left angular and other core regions within DMN, which indicated the disruption of functional connectivity may be one of the underline mechanisms of ApoE-ε4 during AD process.
ABSTRACT
Objective We utilized a joint independent component analysis (Joint ICA), a novel method that combined rs?fMRI and DTI information, to describe comprehensive characteristics of brain functional activities and microstructural changes in the continuum of AD. Methods We employed a Joint ICA to calculate ALFF maps of fMRI data and FA maps of DTI data and fuse them in healthy controls (n=68), SCD (n=35), amnesic MCI (n=47) and AD (n=31). Besides, we applied one way ANOVA to detect the significant differences of joint components among groups, while controlling the age, gender, education, head motion, volumes of gray matter, white matter and CSF. Partial correlation analysis was used to test the relationships between joint ICs and cognitive measures. Results The results showed that there was no inner?group difference in HC and SCD groups (F=14.16, P<0.05). Compared to HC, SCD and AD groups, the ALFF component of aMCI group showed higher values in the bilateral cerebellum, bilateral precuneus, bilateral angular gyrus, bilateral frontal gyrus, bilateral temporal areas, thalamus and left insula. And in these regions, the ALFF of AD group was lower than HC. For the FA component map, same differences were found in the corpus callosum and limbic system. Furthermore, positive partial correlation between the IC weights and Mini?Mental State Examination (MMSE) scores was also found (r=0.29, P<0.01). Conclusions Multi?modal evaluation of AD has been implemented by using Joint ICA analysis of fMRI?DTI, which would contribute to early prediction, diagnosis, and even effective intervention in AD. These findings could help to explain the underlying mechanism of the disease progression.