The relationship between abnormal cortical activity in the anterior cingulate gyrus and cognitive dysfunction in patients with end- stage renal disease: a fMRI study on the amplitude of low- frequency fluctuations.

BACKGROUND: End-stage renal disease (ESRD) patients often have cognitive dysfunction. The abnormal changes in the brains of ESRD patients are difficult to detect with routine imaging examination. Cognitive performance scales are also not an ideal tool because assessments using these scales can be subjective and might be difficult to administer in some ESRD patients. Functional magnetic resonance has the advantages of non-radiation, multidirectional imaging, good repeatability. Using resting-state functional magnetic resonance imaging (rs-fMRI) and an amplitude of low-frequency fluctuation (ALFF) algorithm, this study characterized spontaneous brain activity and explored its relationship with cognitive function in ESRD patients. The aim of this study was to provide objective functional imaging evidence to reveal the pathophysiological mechanism of cognitive dysfunction in ESRD patients. METHODS: This study recruited 35 ESRD patients and 25 healthy controls (HC) who were matched to the ESRD group by age, sex, and years of education. All study subjects were examined by Montreal Cognitive Assessment (MoCA) and rs-fMRI. Data Processing & Analysis of Brain Imaging (DPABI) V4.3 software was used to preprocess the data to obtain ALFF maps. The ALFF value of the cingulate gyrus was compared between the ESRD and HC groups. Subsequently, the correlation between the ALFF value of the cingulate gyrus and the MoCA score was analyzed in ESRD patients. RESULTS: Compared with the HC group, the ESRD group had a significantly lower MoCA score (P<0.05). The ALFF values of the anterior and middle cingulate gyri were significantly lower in the ESRD patients (Gaussian random field (GRF) corrected, voxel-level significance: P<0.001, cluster-level significance: P<0.05). No increased ALFF was observed in any brain regions. The ALFF values of the bilateral anterior cingulate gyri were positively correlated with the MoCA scores (r=0.768, 0.625, GRF corrected, voxel-level significance: P<0.01, cluster-level significance: P<0.05). CONCLUSIONS: Patients with ESRD showed impaired spontaneous brain activity in the bilateral anterior and middle cingulate gyri, suggesting that ALFF of the anterior cingulate gyrus may be an imaging indicator of cognitive dysfunction in ESRD patients.

Alterations of default mode functional connectivity in individuals with end-stage renal disease and mild cognitive impairment.

BACKGROUND: Mild cognitive impairment (MCI) occurs frequently in many end stage renal disease (ESRD) patients, may significantly worsen survival odds and prognosis. However, the exact neuropathological mechanisms of MCI combined with ESRD are not fully clear. This study examined functional connectivity (FC) alterations of the default-mode network (DMN) in individuals with ESRD and MCI. METHODS: Twenty-four individuals with ESRD identified as MCI patients were included in this study; of these, 19 and 5 underwent hemodialysis (HD) and peritoneal dialysis (PD), respectively. Another group of 25 age-, sex- and education level-matched subjects were recruited as the control group. All participants underwent resting-state functional MRI and neuropsychological tests; the ESRD group underwent additional laboratory testing. Independent component analysis (ICA) was used for DMN characterization. With functional connectivity maps of the DMN derived individually, group comparison was performed with voxel-wise independent samples t-test, and connectivity changes were correlated with neuropsychological and clinical variables. RESULTS: Compared with the control group, significantly decreased functional connectivity of the DMN was observed in the posterior cingulate cortex (PCC) and precuneus (Pcu), as well as in the medial prefrontal cortex (MPFC) in the ESRD group. Functional connectivity reductions in the MPFC and PCC/Pcu were positively correlated with hemoglobin levels. In addition, functional connectivity reduction in the MPFC showed positive correlation with Montreal Cognitive Assessment (MoCA) score. CONCLUSION: Decreased functional connectivity in the DMN may be associated with neuropathological mechanisms involved in ESRD and MCI.