Speech silence character as a diagnostic biomarker of early cognitive decline and its functional mechanism: a multicenter cross-sectional cohort study.

BACKGROUND: Language deficits frequently occur during the prodromal stages of Alzheimer's disease (AD). However, the characteristics of linguistic impairment and its underlying mechanism(s) remain to be explored for the early diagnosis of AD. METHODS: The percentage of silence duration (PSD) of 324 subjects was analyzed, including patients with AD, amnestic mild cognitive impairment (aMCI), and normal controls (NC) recruited from the China multi-center cohort, and the diagnostic efficiency was replicated from the Pitt center cohort. Furthermore, the specific language network involved in the fragmented speech was analyzed using task-based functional magnetic resonance. RESULTS: In the China cohort, PSD increased significantly in aMCI and AD patients. The area under the curve of the receiver operating characteristic curves is 0.74, 0.84, and 0.80 in the classification of NC/aMCI, NC/AD, and NC/aMCI+AD. In the Pitt center cohort, PSD was verified as a reliable diagnosis biomarker to differentiate mild AD patients from NC. Next, in response to fluency tasks, clusters in the bilateral inferior frontal gyrus, precentral gyrus, left inferior temporal gyrus, and inferior parietal lobule deactivated markedly in the aMCI/AD group (cluster-level P < 0.05, family-wise error (FWE) corrected). In the patient group (AD+aMCI), higher activation level of the right pars triangularis was associated with higher PSD in in both semantic and phonemic tasks. CONCLUSIONS: PSD is a reliable diagnostic biomarker for the early stage of AD and aMCI. At as early as aMCI phase, the brain response to fluency tasks was inhibited markedly, partly explaining why PSD was elevated simultaneously.

Mortality of Alzheimer's Disease Patients: A 10-Year Follow-up Pilot Study in Shanghai.

BACKGROUND: Identifying risk factors and mortality of individuals with Alzheimer's disease (AD) could have important implications for the clinical management of AD. OBJECTIVE: This pilot study aimed to examine the overall mortality of AD patients over a 10-year surveillance period in Shanghai, China. This study is an extension of our previous investigation on mortality of neurodegenerative diseases. METHODS: One hundred and thirty-two AD patients recruited from the memory clinics of two hospitals in Shanghai in 2007 were followed up until December 31, 2017 or death, representing a follow-up period of up to 10 years. Overall standardized mortality ratios (SMRs) were calculated, and predictors for survival at recruitment were estimated. RESULTS: Sixty-seven patients had died by December 31, 2017, and the SMR at 10 years of follow-up was 1.225 (95% confidence interval 0.944-1.563). Employing Cox's proportional hazard modeling, lower Mini-Mental State Examination score, and comorbid diabetes predicted poor survival in this cohort. CONCLUSION: This pilot study suggests a similar survival trend of patients with AD compared to the general population in Shanghai urban region. Poor cognitive status and comorbid diabetes had a negative impact on the survival of AD patients.

miR-425 deficiency promotes necroptosis and dopaminergic neurodegeneration in Parkinson's disease.

A major hallmark of Parkinson's disease (PD) is the degeneration of dopaminergic neurons in the substantia nigra, and the causative mechanism is thought to be the activation of programmed neuronal death. Necroptosis is a regulated process of cell death triggered by RIPK1. Although the pathophysiology of PD has been studied extensively, the cellular mechanism underlying dopaminergic neuron death remains unclear. In this study, we detected a specific miRNA, miR-425, in response to MPTP toxicity and dopaminergic degeneration. In MPTP-treated mice, we observed necroptosis activation and miR-425 deficiency in the substantia nigra, which is correlated with dopaminergic neuron loss. This miRNA targeted RIPK1 transcripts and promoted the phosphorylation of MLKL and necroptosis. Similarly, in the brains of PD patients, miR-425 deficiency and necroptosis activation were also confirmed in dopaminergic neuron. Furthermore, we found that genetic knockdown of miR-425 aggravated MPTP-induced motor deficits and dopaminergic neurodegeneration via early upregulation of necroptotic genes. Intracerebral miR-425 mimics (AgomiR-425) treatment attenuated necroptosis activation and dopaminergic neuron loss, and improved locomotor behaviors. In conclusion, our study suggests that miR-425 deficiency triggers necroptosis of dopaminergic neurons, and targeting miR-425 in MPTP-treated mice restored dysfunctional dopaminergic neurodegeneration and ameliorated behavioral deficits. These findings identify brain delivery of miR-425 as a potential therapeutic approach for the treatment of PD.

Rho-associated coiled-coil kinase 1 activation mediates amyloid precursor protein site-specific Ser655 phosphorylation and triggers amyloid pathology.

Rho-associated coiled-coil kinase 1 (ROCK1) is proposed to be implicated in Aß suppression; however, the role for ROCK1 in amyloidogenic metabolism of amyloid precursor protein (APP) to produce Aß was unknown. In the present study, we showed that ROCK1 kinase activity and its APP binding were enhanced in AD brain, resulting in increased ß-secretase cleavage of APP. Furthermore, we firstly confirmed that APP served as a substrate for ROCK1 and its major phosphorylation site was located at Ser655. The increased level of APP Ser655 phosphorylation was observed in the brain of APP/PS1 mice and AD patients compared to controls. Moreover, blockade of APP Ser655 phosphorylation, or inhibition of ROCK1 activity with either shRNA knockdown or Y-27632, ameliorated amyloid pathology and improved learning and memory in APP/PS1 mice. These findings suggest that activated ROCK1 targets APP Ser655 phosphorylation, which promotes amyloid processing and pathology. Inhibition of ROCK1 could be a potential therapeutic approach for AD.

Mutation profile of APP, PSEN1, and PSEN2 in Chinese familial Alzheimer's disease.

Causative mutations in the genes encoding amyloid precursor protein (APP), presenilin 1 (PSEN1), or presenilin 2 (PSEN2) account for a majority of cases of familial Alzheimer disease (FAD) inherited in an autosomal-dominant pattern. For the sake of characterizing mutations, index patients from 148 families with FAD were enrolled from mainland China. Sanger sequencing of the genes APP, PSEN1, and PSEN2 was performed to characterize the mutation spectrum of the Chinese population. Thirteen of 148 (8.8%) individuals had possible pathogenic APP, PSEN1, or PSEN2 variants, including 2 (15.4%) APP variants, 8 (61.5%) PSEN1 variants, and 3 (23.1%) PSEN2 variants. PSEN1 variants represented the largest proportion in Chinese FAD, and PSEN2 variants are responsible for late-onset FAD in China. Analysis of genetic-clinical correlations permitted the conclusion that FAD phenotypes were mainly influenced by specific genetic defects.

Current approaches for the management of Parkinson's disease in Chinese hospitals: a cross-sectional survey.

BACKGROUND: Chinese guidelines for management of Parkinson's disease (PD) have been issued and updated regularly since 2006. We undertook a cross-sectional survey to evaluate the impact of the latest edition (2014) on current approaches to the management of PD based on previous pilot works. METHODS: Seven hundred and seventeen participants, divided into 3 groups (GPs, Neurologists, and Specialists), recruited from 138 randomly chosen hospitals from 30 cities across China, participated by completing the questionnaire describing their current approaches before and after the guidelines were issued. RESULTS: Considerable discrepancies in management were apparent across the three categories, with different selection of first-choice medication for PD patients. There were also variations in management of concurrent psychiatric symptoms and dementia. Notably, over 50% of participants reported improvements in PD recognition and management by following the guidelines. CONCLUSIONS: The increasing use of Chinese clinical practice guidelines for PD management is having a positive impact on the optimization of care, which in turn offers important economic benefits.