Objective:To explore the alterations in functional connectivity density (FCD) resulted from mild cognitive impairment (MCI) and their correlations with cognitive scores in various cognitive domains in patients with Parkinson's disease (PD).Methods:Forty-three PD patients admitted to Department of Neurology, Sixth Affiliated Hospital of Nantong University from January 2022 to April 2024 were selected and divided into PD-MCI group (MoCA scores<26) and PD with normal cognition (PD-NC) group (MoCA scores≥26) according to Montreal Cognitive Assessment (MoCA). Another 23 middle-aged and elderly healthy volunteers (HC group) matched with PD patients in age, gender and education level were recruited at the same period. Resting-state functional MRI (rs-fMRI) data were collected and whole brain FCD was calculated. Differences of clinical data, whole brain FCD, and FCD in brain regions with significantly different FCD among the 3 groups were compared. Efficiency of FCD in brain regions with significantly different FCD between PD-MCI group and PD-NC group in differentially diagnosing PD-MCI and PD-NC was analyzed by receiver operating characteristic (ROC) curve. Pearson correlation was used to the analyze the correlations of FCD in brain regions with significantly different FCD with MoCA score and cognitive scores in various cognitive domains.Results:Among the 43 patients, 23 were into the PD-MCI group and 20 into the PD-NC group. PD-MCI group had significantly lower scores in the visuospatial and executive function, abstraction, and delayed memory cognitive domains than PD-NC group ( P<0.05). Brain regions with significantly different FCD among the 3 groups were the right parahippocampal gyrus, left gyrus rectus, right rolandic operculum, left middle occipital gyrus, right precentral gyrus, left middle frontal gyrus, and left medial superior frontal gyrus. Compared with the HC group, the PD-MCI group and PD-NC group had significantly increased FCD at the right parahippocampal gyrus, left gyrus rectus and right rolandic operculum, statistically decreased FCD at the right precentral gyrus, left middle frontal gyrus, and left medial superior frontal gyrus ( P<0.05). Compared with the HC group, the PD-MCI group had significantly increased FCD at the left middle occipital gyrus ( P<0.05). Compared with the PD-NC group, the PD-MCI group had significantly decreased FCD at the right parahippocampal gyrus, and statistically increased FCD at the left middle occipital gyrus and left middle frontal gyrus ( P<0.05). Area under ROC curve (AUC) of FCD in brain regions with significantly different FCD in discriminating PD-MCI and PD-NC was 0.878, with sensitivity of 90.0% and specificity of 91.3%. FCD at right parahippocampal gyrus, left middle occipital gyrus and left middle frontal gyrus was negatively correlated with MoCA score ( P<0.05); FCD at right parahippocampal gyrus was positively correlated with cognitive scores in the visuospatial and executive function, and delayed memory domains ( P<0.05); FCD at left middle occipital gyrus was negatively correlated with cognitive scores in the executive function and visual-spatial skills, and abstraction domains ( P<0.05); FCD at the left medial frontal gyrus was negatively correlated with cognitive scores in the visuospatial and executive function, abstraction and delayed memory domains ( P<0.05). Conclusions:Abnormal FCD can be noted in some brain regions of PD patients, enjoying differences between PD-MCI patients and PD-NC patients. Combined FCD in brain regions with significantly different FCD has high value in differentially diagnosing PD-MCI and PD-NC, and FCD in brain regions with significantly different FCD is correlated with cognitive function changes in PD patients.

Objective:To explore the clinical and electrophysiological characteristics of peripheral neuropathy in prediabetic patients.Methods:Subjects aged 20-65 years with high-risk factors of impaired glycemia enrolled in Beijing Tiantan Hospital, Capital Medical University from 2019 to 2022 were recruited to conduct oral glucose tolerance test, after excluding other causes of neuropathy or radiculopathy. Patients with impaired fasting glucose or impaired glucose tolerance were defined by American Diabetes Association criteria. These patients were divided into clinical polyneuropathy (PN) and clinical non-PN groups, according to the 2010 Toronto consensus criteria and the presence of PN symptoms and signs or not. Nerve conduction studies (NCS), F wave, sympathetic skin response (SSR), R-R interval variation (RRIV) and current perception thresholds (CPT) were performed and the abnormal rate was compared between different electrodiagnostic methods and between clinical subgroups.Results:Among the 73 prediabetic patients ultimately enrolled, only 20 (27.4%) can be diagnosed as clinical PN according to the Toronto consensus criteria. The abnormal rate of CPT (68.5%, 50/73) was significantly higher than those of F wave (2.7%, 2/73), lower limb NCS (0, 0/73), upper limb NCS changes of carpal tunnel syndrome (26.0%, 19/73), SSR (6.8%, 5/73) and RRIV (5.5%, 4/73; McNemar test, all P<0.001). With sinusoid-waveform current stimuli at frequencies of 2 000 Hz, 250 Hz and 5 Hz, the CPT device was used to measure cutaneous sensory thresholds of large myelinated, small myelinated and small unmyelinated sensory fibers respectively. CPT revealed a 21.9% (16/73) abnormal rate of unmyelinated C fiber in the hands of prediabetic patients, significantly higher than that of large myelinated Aβ fibers [8.2% (6/73), χ2=5.352, P=0.021]. Both abnormal rates of small myelinated Aδ [42.5% (31/73)] and unmyelinated C fibers [39.7% (29/73)] in the feet of prediabetic patients were significantly higher than that of large myelinated Aβ fibers [11.0% (8/73), χ2=18.508, 15.965, both P<0.001]. Compared with the clinical non-PN group, the abnormal rates of CPT [90.0% (18/20) vs 60.4% (32/53), χ2=5.904, P=0.015] and SSR [20.0% (4/20) vs 1.9% (1/53), P=0.016) were significantly higher in the clinical PN group. Conclusions:Peripheral neuropathies in prediabetic patients are usually asymptomatic or subclinical, and predispose to affect unmyelinated and small myelinated sensory fibers. Selective electrodiagnostic measurements of small fibers help to detect prediabetic neuropathies in the earliest stages of the disease.