Conversion Of aMCI Research Articles

Resting state functional connectivity abnormalities and delayed recall performance in patients with amnestic mild cognitive impairment.

Amnestic Mild Cognitive Impairment (aMCI) represents the transition between healthy aging and Alzheimer's dementia (AD) wherein gradual impairment of cognitive abilities, especially memory sets in. Impairment in episodic memory, especially delayed recall, is a hallmark of AD and therefore, patients with aMCI with more severe impairment in episodic memory are considered to be at greater risk of imminent conversion to AD. Brain structural and functional abnormalities were examined by comparing gray matter volumes, white matter micro-structural integrity and resting state functional connectivity (rsFC), between patients with aMCI (n= 46) having lower vs. higher episodic memory delayed recall (EM-DR) performance scores, correcting the influences of age, sex, number of years of formal education and total brain volumes using voxel-based morphometry, whole-brain tract based spatial statistics and dual regression analysis respectively. 'Low' performers (n= 27) when compared to 'high' performers (n= 19) showed significantly increased rsFC in the dorsal attention network (DAN) and central executive network (CEN) in the absence of demonstrable gray matter volumetric or white matter micro-structural integrity differences at family-wise error (FWE) corrected (p < 0.05) significance threshold. Follow-up data available for 38 (low performers = 22; high performers = 16) of the above 46 subjects (82.60% follow-up rate) over a median follow-up period of 24.5months revealed that 7 subjects (18.42%) had converted to dementia. These converted subjects included 5 of the 22 low performers (22.72%) and 2 of the 16 high performers (12.5%) within the follow-up sample (n= 38). The results of the study indicate that imminent conversion of aMCI to dementia is higher in low performers in comparison to high performers, which may be characterized by increased rsFC in task positive networks, viz., DAN and CEN, as opposed to gray or white matter structural changes. This finding, therefore, might be considered as a prognostic indicator of progression from aMCI to dementia.

Intra-network and inter-network shared connectivity patterns in patients with remitted late-life depression and amnestic mild cognitive impairment

Objectives Both remitted late-life depression (rLLD) and amnestic mild cognitive impairment (aMCI) alter brain function in individual regions. They are also disconnection syndromes associated with a high-risk of developing Alzheimer's disease (AD). Resting-state functional connectivity magnetic resonance imaging (rs-fcMRI) was performed to define the shared and distinct aberrant patterns in intra-network and inter-network connectivity between rLLD and aMCI. Methods We investigated rs-fcMRI in five functionally well-defined brain networks in 55 rLLD, 87 aMCI, and 114 healthy controls (HC). Results Compared with HC, rLLD showed a reduced degree of functional connectivity in the bilateral inferior temporal cortex and supplemental motor area, and reduced correlations within the sensory-motor network (SMN) and in the default-mode network (DMN) – control network (CON) pair. aMCI showed only focal functional changes in regions of interest pairs, a trend toward increased correlations within the salience network and SMN, and a trend toward reduced correlation in the DMN-CON pair. Furthermore, rLLD exhibited more severely altered functional connectivity compared to aMCI. Interestingly, these altered connectivities were associated with specific multi-domain cognitive and behavioral functions in both rLLD and aMCI. Notably, altered connectivity between right middle temporal cortex and posterior cerebellum was negatively correlated with Mattis Dementia Rating Scale scores in both rLLD and aMCI. Conclusions These results demonstrate that rLLD and aMCI may share convergent and divergent aberrant intra-network and inter-network connectivity patterns. It further suggests that dysfunction in right specific temporal-cerebellum neural circuit may contribute to the similarities observed rLLD and aMCI conversion to AD.

Intereleukin-10 Promoter Polymorphism in Mild Cognitive Impairment and in Its Clinical Evolution

Specific proinflammatory alleles are associated with higher risk of Alzheimer disease (AD) in different onset age. The homozygosis for the A allele of −1082 polymorphism (G/A) of interleukin-10 (IL-10) promotes a higher risk of AD and reduced IL-10 generation in peripheral cells after amyloid stimulation. In this paper we analysed genotype and allele frequencies of this polymorphism in 138 subjects with mild cognitive impairment (MCI) diagnosed, respectively, as amnestic (a-MCI) and multiple impaired cognitive domains (mcd-MCI). The genotype frequencies were similar in a-MCI and AD subjects, whereas in mcd-MCI comparable to controls (AA genotype: 50% in a-MCI, 49.2% in AD, 28.7% in mcd-MCI and 31.8% in controls). Consequently, both allele and genotype distributions were significantly different between a-MCI and mcd-MCI (allele: P = .02, genotype: P < .05). These results support the theory that polymorphisms of cytokine genes can affect neurodegeneration and its clinical progression. IL-10 may partly explain the conversion of a-MCI to AD or be a genetic marker of susceptibility.

Balance Features in Alzheimer's Disease and Amnestic Mild Cognitive Impairment

We evaluated alterations of balance by stabilometry in patients with amnestic mild cognitive impairment (aMCI) and with mild-moderate Alzheimer's disease (AD). Fifteen patients with aMCI and 15 with mild AD were recruited according to the current diagnostic criteria. Fifteen healthy subjects of the same age range were recruited as controls. Stabilometry was carried out using a commercial 4 load cell platform. Statistical analysis of between group differences was performed using one-way analysis of variance for parametric data and Kruskal-Wallis tests for non-parametric data. Spearman correlation coefficients were used to investigate the association between cognitive test scores and stabilometric data. All stabilometry measures were significantly altered in mild AD patients compared to normal controls. Antero-posterior sway was found to be the most sensitive parameter, since it correlated with the ADAS-cog orientation subscale in AD patients, and also discriminated between aMCI and normal controls. Our study shows that impairment in balance is a feature not only of AD, but also of aMCI. The alterations found suggest that a progressive failure of the vestibular system, possibly linked to reduced hippocampal performance, may be responsible for such a feature. Further research must be focused on studying the predictive value of stabilometry in the conversion of aMCI.