Abnormal brain activity patterns during spatial working memory task in patients with end-stage renal disease on maintenance hemodialysis: a fMRI study

Abstract

Hemodialysis (HD) is associated with cognitive impairment in patients with end-stage renal disease (ESRD). However, the neural mechanism of spatial working memory (SWM) impairment in HD-ESRD patients remains unclear. We investigated the abnormal alterations in SWM-associated brain activity patterns in HD-ESRD patients using blood oxygen level-dependent functional magnetic resonance imaging (BOLD-fMRI) technique during n-back tasks. Twenty-two HD-ESRD patients and 22 well-matched controls underwent an fMRI scan while undergoing a three-load n-back tasks with different difficulty levels. Cognitive and mental states were assessed using a battery of neuropsychologic tests. The HD-ESRD patients exhibited worse memory abilities than controls. Compared with the control group, the HD-ESRD patient group showed lower accuracy and longer response time under the n-back tasks, especially in the 2-back task. The patterns of brain activation changed under different working memory loads in the HD-ESRD patients, showing decreased activity in the right medial frontal gyrus and inferior frontal gyrus under 0-back and 1-back task, while more decreased activation in the bilateral frontal cortex, parietal lobule, anterior/posterior cingulate cortex and insula cortex under 2-back task. With the increase of task difficulty, the activation degree of the frontal and parietal cortex decreased. More importantly, we found that lower activation in frontal cortex and parietal lobule was associated with worse cognitive function in the HD-ESRD patients. These results demonstrate that the abnormal brain activity patterns of frontal cortex and parietal lobule may reflect the neural mediation of SWM impairment.

Associations of the Disrupted Functional Brain Network and Cognitive Function in End-Stage Renal Disease Patients on Maintenance Hemodialysis: A Graph Theory-Based Study of Resting-State Functional Magnetic Resonance Imaging

“…In patients with ESRD, the prefrontal lobe is an important brain region related to cognition, and functional and structural abnormalities of the prefrontal lobe have been observed in previous studies ( Ma et al, 2015 ; Jin et al, 2020 ). Other studies have confirmed that for patients with ESRD, prefrontal connectivity is significantly correlated with global cognitive function (i.e., the MoCA score) ( Wu et al, 2020 ; Huang et al, 2021 ). These results suggest that weakening of local information transmission, especially in the prefrontal lobe, may play an important role in the global cognitive decline of patients on MHD and may become an imaging marker for early evaluation of cognitive decline in such patients.…”

Static and Dynamic Characteristics of Functional Network Connectivity in Neurologically Asymptomatic Patients Undergoing Maintenance Hemodialysis: A Resting‐State Functional MRI Study

“…Moreover, the accumulation of urinary toxins is related to the impairment of executive function 37 . Although accumulation of uremic toxins is related to the brain activity and gray matter volume changes of ECN, as reported by previous studies, 5,38 the brain mechanism reflecting the relationship between such accumulation and impaired executive function has not been fully revealed, especially for neurologically asymptomatic patients. Subtle brain abnormalities may help reveal the association between uremic toxins and cognition 39 .…”

Early Stopping in Experimentation With Real-Time Functional Magnetic Resonance Imaging Using a Modified Sequential Probability Ratio Test

“…Note: although only 2 difficulty levels are used here, the setup is able to accommodate any number of difficulty levels. The full duration of the task was 238 scans or 11 min and 54 s. This was based on a moderate length of experimentation for a 1-back block design (e.g., see Daamen et al, 2015 ; Poudel et al, 2015 ; Di et al, 2020 ; Huang et al, 2020 ), allowing approximately 6 min for each difficulty level.…”