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Background Central neurological gait abnormalities (CNGA) are frequently associated with parkinsonism in older adults. However, the neuropathological substrates and the clinical impact of parkinsonism have been not described in CNGA. Objective This cross-sectional study aims to compare the CSF total tau, Aβ1-42, and phosphorylated tau levels in non-Parkinson's disease (PD) patients with CNGA with and without parkinsonism and to study the clinical impact of parkinsonism on gait and cognition. Methods CSF biomarkers were measured by ELISA in 49 non-PD patients with CNGA (77.7±6.6 years; 32.7% women). Gait was quantified with an optoelectronic system and cognition with a comprehensive neuropsychological assessment. Parkinsonism was defined by presence of bradykinesia and at least one of the following signs among muscular rigidity, rest tremor, or postural instability. Results Parkinsonism was identified in 14 CNGA patients (28.6% ). CSF Aβ1-42 level was decreased in CNGA patients with parkinsonism (β: - 189.4; 95% CI [- 352.3; - 26.6]; p = 0.024) even after adjusting for age, gender, comorbidities, and total white matter burden; while CSF total tau and phosphorylated tau levels were similar between CNGA patients with and without parkinsonism. CNGA patients with parkinsonism presented decreased attentional and executive performances but similar gait parameters than those without parkinsonism. Conclusion Parkinsonism represents a phenotype related with amyloidopathy-decreased CSF Aβ1-42 level-in non-PD patients with CNGA. This phenotype is clinically associated with impaired cognition, but similar quantitative gait parameters in comparison to CNGA patients without parkinsonism.

BACKGROUND: Parkinsonism is frequent in neurological conditions affecting gait and cognition, such as idiopathic normal pressure hydrocephalus (iNPH) and iNPH mimics, but its discriminating value between these two groups is still unidentified. OBJECTIVE: This study aims to compare the prevalence of parkinsonism between iNPH and iNPH mimics and its discriminating value. METHODS: Among 141 patients with suspicion of iNPH (75.7±7.1 years; 31.2% women), seventy-nine presented a possible or probable iNPH according to standardized diagnostic criteria and the remaining sixty-two were classified as iNPH mimics. Presence of parkinsonism and other seminal clinical symptoms of iNPH were systematically evaluated by a board-certified neurologist. Covariates include age, gender, comorbidities, and white matter disease burden using the age-related white matter changes scale. Logistic regressions were used to assess the association between parkinsonism and diagnostic groups. RESULTS: Parkinsonism was present in 40.3% of iNPH mimics and 20.3% of iNPH (p-value: 0.015). The presence of parkinsonism, but not iNPH symptoms, was associated with the diagnosis of mimics in the adjusted model (adjusted odds ratio: 2.28; 95% CI: 1.06-4.93), even when age-related white matter changes were accounted for. CONCLUSION: Compared to iNPH, the increased prevalence of parkinsonism in patients with iNPH mimics in the absence of significant white matter disease suggest an underlying neurodegenerative mechanism.

Background: Alzheimer's disease (AD) pathology impacts the response to treatment in patients with idiopathic normal pressure hydrocephalus (iNPH), possibly through changes in resting-state functional connectivity (rs-FC)., Objective: To explore the relationship between cerebrospinal fluid biomarkers of AD and the default mode network (DMN)/hippocampal rs-FC in iNPH patients, based on their outcome after cerebrospinal fluid tap test (CSFTT), and in patients with AD., Methods: Twenty-six iNPH patients (mean age: 79.9 +/- 5.9 years; 12 females) underwent MRI and clinical assessment before and after CSFTT and were classified as responders (Resp) or not (NResp), based on the improvement at the timed up and go test and walking speed. Eleven AD patients (mean age: 70.91 +/- 5.2 years; 5 females), matched to iNPH for cognitive status, were also included. DMN and hippocampal rs-FC was related to amyloid-beta(42) and phosphorylated tau (pTau) levels., Results: Lower amyloid-beta(42 )levels were associated with reduced inter- and intra-network rs-FC in NResp, and the interaction between amyloid-beta(42 )and rs-FC was a predictor of outcome after CSFTT. The rs-FC between DMN and salience networks positively correlated to amyloid-beta(42) levels in both NResp and AD patients. The increase in the inter-network rs-FC after CSFTT was associated with higher pTau and lower amyloid-beta(42) levels in NResp, and to lower pTau levels in Resp., Conclusion: Amyloid-beta(42 )and pTau impact on rs-FC and its changes after CSFTT in iNPH patients. The interaction between AD biomarkers and rs-FC might explain the responder status in iNPH.