Alternation of amplitude of low⁃frequency fluctuation and functional connectivity in the patients of Parkinson's disease with working memory impairment: a resting⁃state fMRI study

Abstract

Objective To explore the characteristics of resting⁃state amplitude of low⁃frequency fluctuation (ALFF) and functional connectivity (FC) in patients with Parkinson's disease (PD) and working memory impairment, and to explore its correlation with cognitive function in order to reveal the abnormal neuronal activity and possibility of brain regions related to working memory impairment neuroimaging mechanism. Methods Thirty⁃nine patients with primary PD from January 2019 to September 2020 were enrolled, using Mini ⁃ Mental State Examination (MMSE), Digital Span Test [DST, including Digit Span Forward Test (DSFT) and Digit Span Backward Test (DSBT)], Clock Drawing Test (CDT) and Animal Verbal Fluency Test (VFT) to evaluate the cognitive function, resting⁃state fMRI (rs⁃fMRI) examination, calculation of ALFF value and FC value between different brain regions and the whole brain. The corrdation between ALFF value and the cognitive function was analysed by Spearman rank correlation. Results According to the DSFT score, 39 patients were divided into PD with working memory impairment group (PD⁃WI group,n = 17) and PD without working memory impairment group (PD⁃normal group, n = 22). MMSE total score (Z = ⁃ 2.149, P = 0.032) and memory (Z = ⁃ 2.465, P = 0.014), attention and calculation (Z = ⁃ 2.239, P = 0.025), language function (Z = ⁃ 2.575, P = 0.010) scores, and DST (Z = ⁃ 5.357, P = 0.000) scores, DSBT (Z = ⁃ 3.967, P = 0.000) and CDT (Z = ⁃ 3.410, P = 0.001) scores in PD⁃WI group were lower than those in PD⁃ normal group. The increased ALFF value was mainly located in the right posterior cingulate gyrus, right thalamus and right precuneus (GRF correction; voxel P < 0.05, cluster P < 0.05). The right posterior cingulate gyrus was the region of interest (ROI). The brain regions with increased FC value were mainly located in the left orbital middle frontal gyrus and the right lingual gyrus (GRF correction; voxel P < 0.05, cluster P < 0.05). Spearman rank correlation analysis showed that the ALFF value at the right cingulate was negatively correlated with the DSFT score (r_s = ⁃ 0.530, P = 0.001). Conclusions PD with working memory impairment patients have different degrees of cognitive dysfunction. The spontaneous neuronal activity in the right posterior cingulate gyrus of the core brain region of the brain default network is enhanced and its correlation with the left orbital middle frontal gyrus and the right lingual gyrus, which is a compensation for early working memory impairment.

DOI：10.3969/j.issn.1672⁃6731.2020.12.003