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Background: Cumulative dementia incidence in Parkinson's disease (PD) is significant, with major personal and socioeconomic impacts on individuals with PD and their carers. Early identification of dementia risk is vital to ensuring optimal intervention. Saccadic deficits often distinguish neurodegenerative disorders and cognitive impairment, but their ability to predict cognitive decline in PD has yet to be determined. The aims of this study were to (1) evaluate baseline (6.4 ± 6.1 months since PD diagnosis) differences in pro-saccadic metrics between those with early PD and healthy age-matched adults; and (2) assess the ability of baseline pro-saccades to predict subsequent cognitive decline over 4.5 years., Methods: One hundred and forty-one PD and 90 age-matched participants recruited at diagnosis underwent saccadometric assessment of pro-saccades at baseline and had cognition assessed at baseline, 18, 36, and 54 months. Pro-saccadic characteristics included latency, duration, amplitude, peak, and average velocity. Cognitive assessment included executive function, attention, fluctuating attention, and memory. Linear mixed-effects models examined pro-saccadic metrics as predictors of cognitive decline over 54 months., Results: Pro-saccades were significantly impaired at baseline in PD compared with controls. Pro-saccadic characteristics of latency, duration, peak, and average velocity predicted decline in global cognition, executive function, attention, and memory over 54 months in PD. In addition, only reduction in global cognition and attention were predicted by pro-saccadic metrics in age-matched adults, indicating that PD findings were not purely age related., Conclusions: Saccadic characteristics are impaired in early PD and are predictive of cognitive decline in several domains. Assessment of saccades may provide a useful non-invasive biomarker for long-term PD cognitive decline in early disease. © 2019 International Parkinson and Movement Disorder Society., (© 2019 International Parkinson and Movement Disorder Society.)

Vision and cognition have both been related to gait impairment in Parkinson's disease (PD) through separate strands of research. The cumulative and interactive effect of both (which we term visuo-cognition) has not been previously investigated and little is known about the influence of cognition on vision with respect to gait. Understanding the role of vision, cognition and visuo-cognition in gait in PD is critical for data interpretation and to infer and test underlying mechanisms. The purpose of this comprehensive narrative review was to examine the interdependent and interactive role of cognition and vision in gait in PD and older adults. Evidence from a broad range of research disciplines was reviewed and summarised. A key finding was that attention appears to play a pivotal role in mediating gait, cognition and vision, and should be considered emphatically in future research in this field., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Introduction: Cholinergic dysfunction contributes to mobility deficits in Parkinson's disease (PD). People with PD rely on limited prefrontal executive-attentional resources for the control of locomotion, including turning. Cortical and behavioral responses to cholinergic augmentation during turning remains unclear. We examined prefrontal cortex (PFC) activity while turning-in-place and spatiotemporal measures of turns in response to usual dopaminergic medication and adjunct cholinergic augmentation.Methods: This study consisted of a single-site, randomized, double-blind crossover trial. Twenty PD participants were assessed in the levodopa-off state and then randomized to either levodopa + donepezil (5 mg) or levodopa + placebo treatments for two weeks followed by a 2-week washout before crossover. The primary outcome was change from off state in PFC activity while turning-in-place (assessed with functional near-infrared spectroscopy). Secondary outcomes were changes in spatiotemporal turning measures (assessed with body-worn inertial measurement units) and accuracy in the secondary task.Results: Nineteen participants completed the trial. While levodopa + placebo had no effect on PFC activity when turning-in-place with a dual-task, levodopa + donepezil led to a large reduction in PFC activity (effect size, -0.82). Spatiotemporal measures of turning improved with both treatments, with slightly greater effect sizes observed for levodopa + donepezil. Additionally, the accuracy in the concurrent cognitive task improved only with levodopa + donepezil (effect size, 0.63).Conclusion: The addition of cholinergic therapy with donepezil (5 mg/day for 2 weeks) to standard dopaminergic therapy reduced the burden on prefrontal executive-attentional resources while turning with a dual-task and improved secondary task accuracy and turning. [ABSTRACT FROM AUTHOR]

Degradation of striatal dopamine in Parkinson's disease (PD) may initially be supplemented by increased cognitive control mediated by cholinergic mechanisms. Shift to cognitive control of walking can be quantified by prefrontal cortex activation. Levodopa improves certain aspects of gait and worsens others, and cholinergic augmentation influence on gait and prefrontal cortex activity remains unclear. This study examined dopaminergic and cholinergic influence on gait and prefrontal cortex activity while walking in PD. A single‐site, randomized, double‐blind crossover trial examined effects of levodopa and donepezil in PD. Twenty PD participants were randomized, and 19 completed the trial. Participants were randomized to either levodopa + donepezil (5 mg) or levodopa + placebo treatments, with 2 weeks with treatment and a 2‐week washout. The primary outcome was change in prefrontal cortex activity while walking, and secondary outcomes were change in gait and dual‐task performance and attention. Levodopa decreased prefrontal cortex activity compared with off medication (effect size, −0.51), whereas the addition of donepezil reversed this decrease. Gait speed and stride length under single‐ and dual‐task conditions improved with combined donepezil and levodopa compared with off medication (effect size, 1 for gait speed and 0.75 for stride length). Dual‐task reaction time was quicker with levodopa compared with off medication (effect size, −0.87), and accuracy improved with combined donepezil and levodopa (effect size, 0.47). Cholinergic therapy, specifically donepezil 5 mg/day for 2 weeks, can alter prefrontal cortex activity when walking and improve secondary cognitive task accuracy and gait in PD. Further studies will investigate whether higher prefrontal cortex activity while walking is associated with gait changes. © 2020 International Parkinson and Movement Disorder Society [ABSTRACT FROM AUTHOR]

Abstract Performance of several tasks simultaneously (dual-tasks) is common in everyday walking. Studies indicate that dual-task walking performance declines with age together with cognitive function, but neural mechanisms underpinning deficits remain unclear. Recent developments in mobile imaging techniques, such as functional near infrared spectroscopy (fNIRS), allow real-time monitoring of cortical activity during walking. This study aimed to: 1) examine activity in motor and cognitive cortical regions when walking with a dual-task in young and older adults; and 2) determine the effect of cognition on dual-task cortical activity changes. Seventeen young (20.3 ± 1.2 years) and eighteen older adults (72.6 ± 8.0 years) performed dual-task conditions, lasting 5 min, with alternating 30-second experimental blocks. The primary outcome was cortical activity, assessed by measuring changes in oxygenated haemoglobin (HbO 2) concentrations. Cortical regions of interest (ROI) included motor regions (premotor cortex (PMC), supplementary motor area (SMA), primary motor cortex (M1)), and cognitive regions (prefrontal cortex (PFC)). Cognitive domains were assessed using standard tests and accelerometers were used to extract gait features. Cortical activity increased with a dual-task in PMC, SMA and M1 but not in PFC regions across groups, with response most evident with initial task exposure. Older adults did not increase SMA activity with a dual-task to the same level as young adults. Dual-task cortical response was consistently associated with greater executive function across groups. In conclusion, both young and older adults responded in a similar manner to dual-task conditions. Dual-task walking activated multiple motor regions in both groups, but no significant change occurred for cognitive region activation. Cortical activation with a dual-task related to executive function. Highlights • Multiple cortical regions are monitored with fNIRS while walking in young and older adults. • Activity increased when walking under dual-task in PMC, SMA and M1, but not PFC in both groups. • Older adults did not increase SMA activity to the same level as young adults under dual-task. • Dual-task cortical response was consistently associated with greater executive function. [ABSTRACT FROM AUTHOR]

Highlights: [•] Techniques for objective measurement of visual sampling lack consistency. [•] Reliability and validity of instruments has not been yet established. [•] Testing recommendations include assessment of basic visual function and cognition. [•] This review informs the development of robust protocols. [ABSTRACT FROM AUTHOR]