The effects of cognitive reserve and lifestyle on cognition and dementia in Parkinson's disease--a longitudinal cohort study

Risk of Dementia in Parkinson's Disease: A Systematic Review and Meta-Analysis

Estimates of the risk of dementia in Parkinson's disease (PDD) vary widely. We aimed to review the incidence of PDD and in a meta-analysis estimate the pooled annual incidence and relative risk of PDD while also exploring factors that may contribute to heterogeneity between studies. Preferred Reporting Items for Systematic reviews and Meta-Analyses guidelines were followed and MEDLINE and EMBASE were searched for articles reporting the number of cases of dementia in a population, followed longitudinally, with a minimum of 100 dementia-free Parkinson's disease (PD) patients at baseline. Meta-analyses and meta-regressions were used to estimate the pooled incidence rate of PDD and the relative risk of PDD versus healthy controls (HC). A total of 32 studies were identified, 25 reporting the incidence of PDD and 10 reporting the relative risk of PDD versus HC. The pooled incidence rate of PDD was 4.45 (95% confidence interval [CI], 3.91-4.99) per 100 person-years at risk, equating to a 4.5% annual risk of dementia in a PD prevalent population. The relative risk of PDD was estimated to be 3.25 (95% CI, 2.62-4.03) times greater than HC. Factors contributing to study heterogeneity and disparities in the estimated risk of PDD include the age of patients, year of recruitment, and study location. Significant gaps remain with no studies identified in several geographical regions. Future studies should stratify by age and standardize reporting to reduce overall heterogeneity. © 2024 The Author(s). Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Mid- and late-life lifestyle activities as main drivers of general and domain-specific cognitive reserve in individuals with Parkinson's disease: cross-sectional and longitudinal evidence from the LANDSCAPE study

BACKGROUND

Cognitive reserve (CR) is considered a protective factor for cognitive function and may explain interindividual differences of cognitive performance given similar levels of neurodegeneration, e.g., in Alzheimer´s disease. Recent evidence suggests that CR is also relevant in Parkinson's disease (PD).

OBJECTIVE

We aimed to explore the role of life-stage specific CR for overall cognition and specific cognitive domains cross-sectionally and longitudinally in PD.

METHODS

The cross-sectional analysis with data from the DEMPARK/LANDSCAPE study included 81 individuals without cognitive impairment (PD-N) and 87 individuals with mild cognitive impairment (PD-MCI). Longitudinal data covered 4 years with over 500 observations. CR was operationalized with the Lifetime of Experiences Questionnaire (LEQ), capturing the complexity of lifestyle activities across distinct life-stages. Cognition was assessed using a comprehensive neuropsychological test battery.

RESULTS

Higher LEQ scores, particularly from mid- and late-life, were observed in PD-N compared to PD-MCI [F(1,153) = 4.609, p = .033, ηp2 = 0.029]. They were significantly associated with better cognitive performance (0.200 ≤ β ≤ 0.292). Longitudinally, linear mixed effect models (0.236 ≤ marginal R2 ≤ 0.441) revealed that LEQ scores were positively related to cognitive performance independent of time. However, the decline in overall cognition and memory over time was slightly more pronounced with higher LEQ scores.

CONCLUSIONS

This study emphasizes the association between complex lifestyle activities and cognition in PD. Data indicate that while CR might be related to a delay of cognitive decline, individuals with high CR may experience a more pronounced drop in overall cognition and memory. Future studies will have to replicate these findings, particularly regarding domain-specific effects and considering reverse causal mechanisms.

GBA moderates cognitive reserve's effect on cognitive function in patients with Parkinson's disease

BACKGROUND

Cognitive reserve (CR) involves an individual's ability to maintain cognitive vitality over their lifespan. Glucocerebrosidase (GBA) gene mutations contribute to additional effects on cognitive function in Parkinson's disease (PD) patients, but the interplay between GBA mutations and CR remains unclear. We investigated the interactions among CR, GBA, and diseases, aiming to examine whether the CR established at different stages interacts with specific genotypes to affect cognitive function.

METHODS

Three hundred and eighteen participants' CR indicators (i.e., education, occupation, and social function) and comprehensive neuropsychological function (i.e., tests for executive function, attention/working memory, visuospatial function, memory, and language) were evaluated.

RESULTS

We found that CR established in a specific life stage influences the individual's cognitive function, particularly in PD, based on their distinct GBA rs9628662 genotypes. Attention/working memory and memory performance are affected by occupational complexity in midlife in PD patients with the GG genotype (q < 0.0001; q < 0.0001) and healthy adults with the T genotype (q = 0.0440; q < 0.0001). Language is influenced by early education and occupation, and the effects of occupation are also observed in PD patients with the GG genotype (q = 0.0040) and in healthy adults carrying the T genotype (q = 0.0040).

CONCLUSIONS

CR, established at different life stages, can be influenced by the GBA rs9628662 genotype, impacting later-life cognition. Validating genotypes and incorporating genotype information when assessing cognitive reserve effects is crucial and can enhance targeted cognitive training.

Influence of cognitive reserve on cognitive and motor function in α-synucleinopathies: A systematic review and multilevel meta-analysis

Cognitive reserve has shown promise as a justification for neuropathologically unexplainable clinical outcomes in Alzheimer's disease. Recent evidence suggests this effect may be replicated in conditions like Parkinson's disease, dementia with Lewy bodies, and multiple system atrophy. However, the relationships between cognitive reserve and different cognitive abilities, as well as motor outcomes, are still poorly understood in these conditions. Additionally, it is unclear whether the reported effects are confounded by medication. This review analysed studies investigating the relationship between cognitive reserve and clinical outcomes in these α-synucleinopathy cohorts, identified from MEDLINE, Scopus, psycINFO, CINAHL, and Web of Science. 85 records, containing 176 cognition and 31 motor function effect sizes, were pooled using multilevel meta-analysis. There was a significant, positive association between higher cognitive reserve and both better cognition and motor function. Cognition effect sizes differed by disease subtype, cognitive reserve measure, and outcome type; however, no moderators significantly impacted motor function. Review findings highlight the clinical implications of cognitive reserve and importance of engaging in reserve-building behaviours.

Risk of impairment in cognitive instrumental activities of daily living for sexual and gender minority adults with reported Parkinson's disease

Objective: To investigate the risk of impairment in cognitive instrumental activities of daily living (IADL) for people with Parkinson's (PwP) identifying as sexual and/or gender minorities (SGM). Method: Data were obtained from Fox Insight, an online, longitudinal study with self/informant-report questionnaires from PwP and people without Parkinson's. Groups consisted of PwP without cognitive IADL impairment at baseline, identifying as (1) SGM with female sex assigned at birth (SGM-F, n = 75); (2) cisgender, heterosexual with female sex assigned at birth (CH-F, n = 2046); (3) SGM with male sex assigned at birth (SGM-M, n = 84); (4) cisgender, heterosexual with male sex assigned at birth (CH-M, n = 2056). Impairment in cognitive IADL was based on Penn Parkinson's Daily Activities Questionnaire-15 (PDAQ-15). Group differences for PDAQ-15 and impairment likelihood during follow-up were assessed with unadjusted models and adjusting for variables that differed between the groups. Results: SGM-F were the youngest at Parkinson's diagnosis; SGM-M had the lowest PDAQ-15 at baseline (p ≤ .014 for all). Scores declined more for males than females in unadjusted and adjusted models (p < .001 for both). In unadjusted models, SGM-M had a higher impairment risk than PwP identifying as cisgender and heterosexual (p ≤ .018). In adjusted models, females had a lower impairment risk than males (p < .001). Age, education, and discrimination level were significant moderators (p < .001 for all). Conclusions: SGM-M can be at a higher risk for impairment in cognitive IADL, associated with social determinants. Female sex assigned at birth may be associated with a lower level of impairment risk, although this advantage can disappear with social determinants.

Structural underpinnings and long-term effects of resilience in Parkinson's disease

Resilience in neuroscience generally refers to an individual's capacity to counteract the adverse effects of a neuropathological condition. While resilience mechanisms in Alzheimer's disease are well-investigated, knowledge regarding its quantification, neurobiological underpinnings, network adaptations, and long-term effects in Parkinson's disease is limited. Our study involved 151 Parkinson's patients from the Parkinson's Progression Marker Initiative Database with available Magnetic Resonance Imaging, Dopamine Transporter Single-Photon Emission Computed Tomography scans, and clinical information. We used an improved prediction model linking neuropathology to symptom severity to estimate individual resilience levels. Higher resilience levels were associated with a more active lifestyle, increased grey matter volume in motor-associated regions, a distinct structural connectivity network and maintenance of relative motor functioning for up to a decade. Overall, the results indicate that relative maintenance of motor function in Parkinson's patients may be associated with greater neuronal substrate, allowing higher tolerance against neurodegenerative processes through dynamic network restructuring.

Cognitive Reserve in Parkinson's Disease without Dementia: β-Amyloid and Metabolic Assessment

BACKGROUND

Cognitive reserve (CR) is the mismatch between preserved cognition and neuropathological damage. Amyloidopathy in Parkinson's disease (PD) could be associated with faster progression to dementia, but the putative protective effect of CR is unknown.

OBJECTIVES

To evaluate the effect of CR on β-amyloid burden and brain metabolism in non-demented PD subjects.

METHODS

Participants with PD (n = 53) underwent a clinical evaluation, [18 F]-fluorodeoxyglucose and [18 F]-flutemetamol positron emission tomography magnetic resonances, and were classified according to CR. The metabolic pattern of 16 controls was compared to PD subjects.

RESULTS

The PD subjects showed hypometabolism mainly in the bilateral posterior cortex. Superior-CR subjects (n = 22) exhibited better cognitive performance, increased amyloid burden, and higher metabolism in several right hemisphere areas compared to low-medium-CR subjects (n = 31).

CONCLUSIONS

Higher CR in non-demented PD is associated with better cognitive performance, which might reduce vulnerability to the effect of β-amyloid. Whether superior CR leads to protection against metabolic deterioration, and predominantly right hemisphere involvement, deserves further exploration.

Multifactorial assessment of Parkinson's disease course and outcomes using trajectory modeling in a multiethnic, multisite cohort - extension of the LONG-PD study

Background

The severity, progression, and outcomes of motor and non-motor symptoms in Parkinson's disease (PD) are quite variable. Following PD cohorts holds promise for identifying predictors of disease severity and progression.

Methods

PD patients (N = 871) were enrolled at five sites. Enrollment occurred within 5 years of initial motor symptom onset. Disease progression was assessed annually for 2-to-10 years after onset. Group-based trajectory modeling was used to identify groups differing in disease progression. Models were developed for UPDRS-III scores, UPDRS-III tremor and bradykinesia-rigidity subscores, Hoehn & Yahr (H&Y) stage, Mini-Mental Status Exam (MMSE) scores, and UPDRS-III, H&Y and MMSE scores considered together. Predictors of trajectory-group membership were modeled simultaneously with the trajectories. Kaplan-Meier survival analysis evaluated survival free of PD outcomes.

Results

The best fitting models identified three groups. One showed a relatively benign, slowly progressing trajectory (Group 1), a second showed a moderate, intermediately progressing trajectory (Group 2), and a third showed a more severe, rapidly progressing trajectory (Group 3). Stable trajectory-group membership occurred relatively early in the disease course, 5 years after initial motor symptom. Predictors of intermediate and more severe trajectory-group membership varied across the single variable models and the multivariable model jointly considering UPDRS-III, H&Y and MMSE scores. In the multivariable model, membership in Group 2 (28.4% of patients), relative to Group 1 (50.5%), was associated with male sex, younger age-at-onset, fewer education-years, pesticide exposure, absence of reported head injury, and akinetic/rigid subtype at initial presentation. Membership in Group 3 (21.3%), relative to Group 1, was associated with older age-at-onset, fewer education-years, pesticide exposure, and the absence of a tremor-predominant subtype at initial presentation. Persistent freezing, persistent falls, and cognitive impairment occurred earliest and more frequently in Group 3, later and less frequently in Group 2, and latest and least frequently in Group 1. Furthermore, autonomic complications, dysphagia, and psychosis occurred more frequently in Groups 2 and 3 than in Group 1.

Conclusion

Modeling disease course using multiple objective assessments over an extended follow-up duration identified groups that more accurately reflect differences in PD course, prognosis, and outcomes than assessing single parameters over shorter intervals.

Education, incident cancer, and rate of memory decline in a national sample of US adults in mid-to-later-life

INTRODUCTION

Middle-aged and older adults who develop cancer experience memory loss following diagnosis, but memory decline in the years before and after cancer diagnosis is slower compared to their cancer-free counterparts. Educational attainment strongly predicts memory function during aging, but it is unclear whether education protects against memory loss related to cancer incidence or modifies long-term memory trajectories in middle-aged and older cancer survivors.

MATERIALS AND METHODS

Data were from 14,449 adults (3,248 with incident cancer, excluding non-melanoma skin cancer) aged 50+ in the population-based US Health and Retirement Study from 1998 to 2016. Memory was assessed every two years as a composite of immediate and delayed word recall tests and proxy assessments for impaired individuals. Memory scores all time points were standardized at to the baseline distribution. Using multivariate-adjusted linear mixed-effects models, we estimated rates of memory decline in the years before cancer diagnosis, shortly after diagnosis, and in the years after diagnosis. We compared rates of memory decline between incident cancer cases and age-matched cancer-free adults, overall and according to level of education (<12 years, "low"; 12 to <16 years, "intermediate"; ≥16 years, "high").

RESULTS

Incident cancer diagnoses were followed by short-term declines in memory averaging 0.06 standard deviation (SD) units (95% confidence interval [CI]: -0.084, -0.036). Those with low education experienced the strongest magnitude of short-term decline in memory after diagnosis (-0.10 SD units, 95% CI: -0.15, -0.05), but this estimate was not statistically significantly different from the short-term decline in memory experienced by those with high education (-0.04 SD units, 95% CI: -0.08, 0.01; p-value for education as an effect modifier = 0.15). In the years prior to and following an incident cancer diagnosis, higher educational attainment was associated with better memory, but it did not modify the difference in rate of long-term memory decline between cancer survivors and those who remained cancer-free.

DISCUSSION

Education was associated with better memory function over time among both cancer survivors and cancer-free adults aged 50 and over. Low education may be associated with a stronger short-term decline in memory after a cancer diagnosis.

How Cognitive Reserve should Influence Rehabilitation Choices using Virtual Reality in Parkinson’s Disease

Virtual reality (VR) is used in the rehabilitation of patients with Parkinson's disease (PD) in several studies. In VR trials, the motor, physical characteristics, and the degree of the disease are often well defined, while PD cognitive reserve is not. This systematic review was performed to define a cognitive profile for patients with PD who could best benefit from using VR to enhance functional motor aspects during rehabilitation. PubMed, Cochrane Library, Scopus, and Web of Sciences databases were analysed to identify randomized clinical trials (RCT) and randomized pilot trials that addressed the rehabilitation of motor symptoms in subjects with PD using VR. The included studies used Mini-Mental State Examination (MMSE) or Montreal Cognitive Assessment (MoCA) to evaluate the cognitive aspect. Only articles written in English and with full texts were considered. The risk of bias from all included studies was assessed based on the Cochrane risk-of-bias tool and the PRISMA guideline was considered. Eighteen articles were eligible for review, including three randomized pilot trials. All studies aimed to evaluate the effect of VR on the motor aspects typically affected by PD (balance, postural control, risk of falls, walking, and reaching). The most widely adopted approach has been nonimmersive VR, except for one study that used immersive VR. Both the benefits of physical activity on the motor symptoms of patients with PD and the impact of cognitive reserve during the rehabilitation of these patients were highlighted. The analysis of the results allowed us to outline the ideal cognitive profile of patients with PD who can benefit from the effects of rehabilitation using VR.

Cognitive reserve: a multidimensional protective factor in Parkinson's disease related cognitive impairment

We explored the association between cognitive reserve (CR) and Parkinson' s disease (PD) related cognitive deterioration.Forty PD patients and 12 matched healthy controls (HC) were enrolled. The PD group was balanced for the presence/absence of cognitive impairment. All participants underwent MOCA. CR was measured by the Brief Intelligence Test, and a new comprehensive tool, named Cognitive Reserve Test (CoRe-T), including sections on leisure activities and creativity.Participants with higher CR obtained a better MOCA score irrespective of the group they belonged to. At the same time, irrespective of the CR level, the performance of the HC group was always better in comparison to the PD group. Within the PD group, a higher frequency of leisure activities was associated to be cognitively unimpaired, independently by the severity of motor symptoms and age.CR could help to cope with PD-related cognitive decline. Its multidimensional nature could have important applications in prevention and rehabilitation interventions.

The influence of cognitive reserve in the protection of the cognitive status after an acquired brain injury: A systematic review

BACKGROUND

Cognitive Reserve (CR) hypothesis was introduced to account for the variability in cognitive performance of patients with similar degrees of brain injury or pathology. The individual variability of CR is modulated by the interaction of innate capacities and exposures throughout life, which can act as protectors against neuropathology's clinical effects. Individuals with higher CR appear to have better cognitive performance after a brain injury. The present review aimed to identify and map the scientific evidence available in literature regarding CR's influence in protecting the cognitive status after an Acquired Brain Injury (ABI).

METHOD

A systematic review was performed for published studies until October 2020 in PubMed, Scopus, and CINAHL electronic databases. Studies regarding CR's influence in protecting the cognitive status after an ABI were included in this review. The Newcastle-Ottawa Scale was used to assess risk of bias in the included studies. This systematic review was recorded in the International Prospective Register of Systematic Reviews (PROSPERO) under the number CRD42021236594.

RESULTS

Twenty-one studies published between 2003 and 2020 were selected and analyzed. The literature analysis showed that CR has a positive effect on cognitive status after an ABI. Various proxies were used to estimate CR, including estimated premorbid IQ, education, occupation attainment, socioeconomic status, leisure activities, bilingualism, and social integration. CR proxies constitute a set of variables that may have a significant influence on cognitive status. Higher CR levels were associated with lower cognitive impairment after an ABI.

CONCLUSIONS

Although more research is necessary for a complete understanding of CR's impact on cognition, the synthesis of these studies confirmed that there is evidence on the beneficial impact of CR on cognitive status after an ABI. These findings support CR's cognitive status role following an ABI and may provide additional information for prognosis and rehabilitation plans.

A lifestyle score in childhood and adolescence was positively associated with subsequently measured fluid intelligence in the DONALD cohort study

PURPOSE

Lifestyle scores which combine single factors such as diet, activity, or sleep duration showed associations with cognitive decline in adults. However, the role of a favourable lifestyle in younger age and the build-up of cognitive reserve is less clear, which is why we investigated longitudinal associations between a lifestyle score in childhood and adolescence and fluid intelligence obtained on average 6 years later.

METHODS

In the DONALD cohort, a lifestyle score of 0 to 4 points including healthy diet and duration of moderate-to-vigorous physical activity, sedentary behaviour and sleep was repeatedly assessed in participants aged 5 and 19 years. Data on fluid intelligence were assessed via a German version of the culture fair intelligence test (CFT), using CFT 1-R in children 8.5 years of age or younger (n = 62) or CFT 20-R in participants older than 8.5 years (n = 192). Multivariable linear regression models were used to investigate prospective associations between the lifestyle score and the fluid intelligence score.

RESULTS

Mean lifestyle score of all participants was 2.2 (0.7-4) points. A one-point increase in the lifestyle score was associated with a higher fluid intelligence score (4.8 points [0.3-7.3], p = 0.0343) for participants completing the CFT 20-R. Furthermore, each additional hour of sedentary behaviour was associated with a lower fluid intelligence score (- 3.0 points [- 5.7 to - 0.3], p = 0.0313). For younger participants (CFT 1-R), no association was found in any analysis (p > 0.05).

CONCLUSION

A healthy lifestyle was positively associated with fluid intelligence, whereby sedentary behaviour itself seemed to play a prominent role.

Social withdrawal in Parkinson's disease: A scoping review

BACKGROUND

Parkinson's disease (PD) can interfere with individuals' social functioning and lead to social withdrawal. Social withdrawal may result in negative outcomes for persons with PD and their caregivers, such as decreased quality of life. It is necessary to understand the nature of social withdrawal in PD in order to develop strategies to address this issue and prevent negative outcomes.

OBJECTIVE

The purpose of this scoping review was to synthesize existing evidence regarding social withdrawal in PD.

METHODS

We searched PubMed, CINAHL, and PsycINFO for studies of social withdrawal in individuals living with PD. Findings were organized according to study characteristics, measurement and description of social withdrawal, prevalence, associated factors, and interventions.

RESULTS

Fifty-eight studies were included. We found that persons with PD reduced social activities voluntarily and involuntarily, and social withdrawal was related to various factors including physical, cognitive, and psychiatric symptoms and perceived stigma. Community-based social activity programs appeared to improve social participation. Few studies employed longitudinal methods or tested interventions to reduce social withdrawal.

CONCLUSIONS

Social withdrawal is associated with various negative outcomes in PD, though more research is needed to understand the true scope of this problem. Limitations in social withdrawal research include vague conceptualization and methodological limitations (i.e., instrumentation and study design), as well as a paucity of interventional studies. The findings of this review can be used to guide hypothesis generation and future study design, with the ultimate goal of mitigating social withdrawal and improving quality of life for people with PD.

Effects of Cognitive Reserve on Cognition in Individuals With Central Nervous System Disease

Cognitive reserve (CR) has been proposed to account for functional outcome differences in brain pathology and its clinical manifestations. The purpose of our paper is to systematically review the effects of CR on cognitive outcomes in individuals with neurodegenerative and structural CNS diseases. We performed a systematic search of PubMed, CINAHL (Cumulative Index to Nursing and Allied Health Literature), and PsychInfo using the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. Seventeen studies met the predetermined inclusion criteria and were selected for review. Education level was the most commonly used measure for CR, and various neuropsychological tests were used to measure cognitive outcomes. Regardless of the CNS disease of the individuals, almost all of the studies reported a positive association between CR and cognitive outcomes when they were evaluated cross-sectionally. However, when evaluated longitudinally, CR had either no effect on, or a negative association with, cognitive outcomes. Based on studies across a broad spectrum of CNS diseases, our findings suggest that CR may serve as a predictor of cognitive outcomes in individuals with CNS diseases. However, studies to date are limited by a lack of imaging analyses and standardized assessment strategies. The ability to use a standardized measure to assess the longitudinal effects of CR may allow for the development of more targeted treatment methods, resulting in improved disease outcomes for individuals.

Electroencephalography, Magnetoencephalography, and Cognitive Reserve: A Systematic Review

OBJECTIVE

Cognitive reserve (CR) is the capacity to adapt to (future) brain damage without any or only minimal clinical symptoms. The underlying neuroplastic mechanisms remain unclear. Electrocorticography (ECOG), electroencephalography (EEG), and magnetoencephalography (MEG) may help elucidate the brain mechanisms underlying CR, as CR is thought to be related to efficient utilization of remaining brain resources. The purpose of this systematic review is to collect, evaluate, and synthesize the findings on neural correlates of CR estimates using ECOG, EEG, and MEG.

METHOD

We examined articles that were published from the first standardized definition of CR. Eleven EEG and five MEG cross-sectional studies met the inclusion criteria: They concerned original research, analyzed (M)EEG in humans, used a validated CR estimate, and related (M)EEG to CR. Quality assessment was conducted using an adapted form of the Newcastle-Ottawa scale. No ECOG study met the inclusion criteria.

RESULTS

A total of 1383 participants from heterogeneous patient, young and older healthy groups were divided into three categories by (M)EEG methodology: Eight (M)EEG studies employed event-related fields or potentials, six studies analyzed brain oscillations at rest (of which one also analyzed a cognitive task), and three studies analyzed brain connectivity. Various CR estimates were employed and all studies compared different (M)EEG measures and CR estimates. Several associations between (M)EEG measures and CR estimates were observed.

CONCLUSION

Our findings support that (M)EEG measures are related to CR estimates, particularly in healthy individuals. However, the character of this relationship is dependent on the population and task studied, warranting further studies.

Normal cognition in Parkinson's disease may involve hippocampal cholinergic compensation: An exploratory PET imaging study with [18F]-FEOBV

BACKGROUND

Severe cholinergic degeneration is known to occur in Parkinson's disease (PD) and is thought to play a primary role in the cognitive decline associated with this disease. Although cholinergic losses occur in all patients with PD, cognitive performance remains normal for many of them, suggesting compensatory mechanisms in those.

OBJECTIVES

This exploratory study aimed at verifying if normal cognition in PD may involve distinctive features of the brain cholinergic systems.

METHODS

Following extensive neuropsychological screening in 25 patients with PD, 12 were selected and evenly distributed between a cognitively normal (PD-CN) group, and a mild cognitive impairment (PD-MCI) group. Each group was compared with matched healthy volunteers (HV) on standardized cognitive scales (MoCA, PDCRS), and PET imaging with [¹⁸F]-FEOBV, a sensitive measurement of brain cholinergic innervation density.

RESULTS

[¹⁸F]-FEOBV uptake reductions were observed in PD-CN as well as in PD-MCI, with the lowest values located in the posterior cortical areas. However, in PD-CN but not in PD-MCI, there was a significant and bilateral increase of [¹⁸F]-FEOBV uptake, exclusively located in the hippocampus. Significant correlations were observed between cognitive performance and hippocampal [¹⁸F]-FEOBV uptake.

CONCLUSION

These findings suggest a compensatory upregulation of the hippocampal cholinergic innervation in PD-CN, which might underly normal cognitive performances in spite of cortical cholinergic denervation in other regions.

Negative Effects of COVID-19 Stay-at-Home Mandates on Physical Intervention Outcomes: A Preliminary Study

BACKGROUND

Due to the COVID-19 pandemic, beneficial physical intervention classes for individuals with Parkinson's disease (PD) were cancelled.

OBJECTIVE

To understand effects of the COVID-19 stay-at-home mandate and the inability to participate in recommended and structured physical interventions as a consequence of these mandates, specifically designed mobile assessments were used that collected both self-reporting information and objective task-based metrics of neurocognitive functions to assess symptom changes for individuals with PD.

METHODS

Self-reporting questionnaires focusing on overall quality of life (e.g., when individuals typically feel at their best, changes in activity levels, and symptom progression) were given to all individuals (n = 28). In addition, mobile-based neurocognitive assessments were administered to a subset of the population (n = 8) to quantitatively assess changes due to COVID-19 restrictions.

RESULTS

The highest self-reported factors in which individuals denoted feeling their best were after exercise (67.86%) and being in a comfortable and supportive environment (60.71%). Objective measures found overall duration of physical activity during the stay-at-home mandate decreased significantly (p = 0.022). With the lack of overall activity, 82.14%of individuals self-reported having at least one symptom that worsened moderately or higher. Further testing, using mobile-based assessments, showed average completion times of functional tasks increased, taking about 2.1 times longer, while accuracy metrics showed overall degradation.

CONCLUSION

Although the COVID-19 stay-at-home mandate was intended to help protect individuals at high risk from coming into contact with the virus, it also prevented individuals from receiving recommended supervised exercise interventions resulting in significant negative effects in social well-being and across motor and speech neurocognitive tasks for individuals with PD.

Cognitive Reserve, Executive Function, and Memory in Parkinson's Disease

Cognitive impairment is acknowledged as a feature of Parkinson’s disease (PD), and the most common cognitive declines are in executive function (EF) and memory. Cognitive reserve (CR) may offer some protection against cognitive dysfunction in PD. The present study used two proxies of CR (years of education, premorbid IQ) to examine the relationship between CR and (i) EF (ii) memory in a large PD sample (n = 334). Two aspects of EF were examined, including verbal fluency and planning skills. Two aspects of verbal memory were examined, including immediate recall and delayed recall. For EF, both CR proxies significantly predicted verbal fluency, but only years of education predicted planning skills. Years of education significantly predicted immediate recall, but premorbid IQ did not. Neither CR proxy predicted delayed recall. These findings suggest that CR, in particular years of education, may contribute to EF and memory function in those with PD. A key finding of this study is the varying contribution of CR proxies to different aspects of the same cognitive domain. The findings indicate that using only one proxy has the potential to be misleading and suggest that when testing the relationship between CR and cognition, studies should include tasks that measure different aspects of the cognitive domain(s) of interest.

Attention in post-lexical processes of utterance production: Dual-task cost in younger and older adults

There is a general agreement that speaking requires attention at least for conceptual and lexical processes of utterance production. However, conflicting results have been obtained with dual-task paradigms using either repetition tasks or more generally tasks involving limited loading of lexical selection. This study aimed to investigate whether post-lexical processes recruit attentional resources. We used a new dual-task paradigm in a set of experiments where a continuous verbal production task involved either high or low demand on lexical selection processes. Experiment 1 evaluates lexical and post-lexical processes with a semantic verbal fluency task, whereas Experiments 2 and 3 focus on post-lexical processes with a non-propositional speech task. In each experiment, two types of non-verbal secondary tasks were used: processing speed (simple manual reaction times) or inhibition (Go/No-go). In Experiment 1, a dual-task cost was observed on the semantic verbal fluency task and each non-verbal task. In Experiment 2, a dual-task cost appeared on the non-verbal tasks but not on the speech task. The same paradigm was used with older adults (Experiment 3), as increased effort in post-lexical processes has been associated with ageing. For older adults, a dual-task cost was also observed on the non-propositional verbal task when speech was produced with the inhibition non-verbal task. The results suggest an attentional cost on post-lexical processes and strategic effects in the resolution of the dual-task.

Cognitive reserve in amyotrophic lateral sclerosis (ALS): a population-based longitudinal study

BACKGROUND

Amyotrophic lateral sclerosis (ALS) is often associated with cognitive and/or behavioural impairment. Cognitive reserve (CR) may play a protective role in offsetting cognitive impairment. This study examined the relationship between CR and longitudinal change in cognition in an Irish ALS cohort.

METHODS

Longitudinal neuropsychological assessment was carried out on 189 patients over 16 months using the Edinburgh cognitive and behavioural ALS screen (ECAS) and an additional battery of neuropsychological tests. CR was measured by combining education, occupation and physical activity data. Joint longitudinal and time-to-event models were fitted to investigate the associations between CR, performance at baseline and decline over time while controlling for non-random drop-out.

RESULTS

CR was a significant predictor of baseline neuropsychological performance, with high CR patients performing better than those with medium or low CR. Better cognitive performance in high CR individuals was maintained longitudinally for ECAS, social cognition, executive functioning and confrontational naming. Patients displayed little cognitive decline over the course of the study, despite controlling for non-random drop-out.

CONCLUSIONS

These findings suggest that CR plays a role in the presentation of cognitive impairment at diagnosis but is not protective against cognitive decline. However, further research is needed to examine the interaction between CR and other objective correlates of cognitive impairment in ALS.

Environmental Enrichment Rescues Functional Deficit and Alters Neuroinflammation in a Transgenic Model of Tauopathy

Alzheimer's disease (AD) is the most frequent neurodegenerative disorder, affecting over 44 million people worldwide. There are no effective pharmaco-therapeutic options for prevention and treatment of AD. Non-pharmacological approaches may help patients suffering from AD to significantly ameliorate disease progression. In this study, we exposed a transgenic rat model (tg) of human tauopathy to enriched environment for 3 months. Behavioral testing at 6 months of age revealed improvement in functional deficits of tg rats reared under enriched conditions, while sedentary tg rats remained severely impaired. Interestingly, enriched environment did not reduce tau pathology. Analysis of neurotrophic factors revealed an increase of nerve growth factor (NGF) levels in the hippocampus of both enriched groups (tg and non-tg rats), reflecting a known effect of enriched environment on the hippocampal formation. On the contrary, NGF levels decreased markedly in the brainstem of enriched groups. The non-pharmacological treatment also reduced levels of tissue inhibitor of metalloproteinase 1 in the brainstem of transgenic rats. Expression analysis of inflammatory pathways revealed upregulation of microglial markers, such as MHC class II and Cd74, whereas levels of pro-inflammatory cytokines remained unaffected by enriched environment. Our results demonstrate that exposure to enriched environment can rescue functional impairment in tau transgenic rats without reducing tau pathology. We speculate that non-pharmacological treatment modulates the immune response to pathological tau protein inclusions, and thus reduces the damage caused by neuroinflammation.

Non-motor complications in late stage Parkinson's disease: recognition, management and unmet needs

Introduction: The burden of non-motor symptoms (NMS) is a major determinant of health-related quality of life in Parkinson's disease (PD), particularly at its late stage.Areas covered: The late stage is usually defined as the period from unstable advanced to the palliative stage, characterized by a combination of emerging treatment-resistant axial motor symptoms (freezing of gait, postural instability, falls and dysphagia), as well as both non-dopaminergic and dopaminergic NMS: cognitive decline, neuropsychiatric symptoms, aspects of dysautonomia, pain and sleep disturbances (insomnia and excessive day-time sleepiness). Here, the authors summarize the current knowledge on NMS dominating the late stage of PD and propose a pragmatic and clinically focused approach for their recognition and treatment.Expert opinion: The NMS progression pattern is complex and remains under-researched. While dopamine-dependent NMS may improve with dopamine replacement therapy, non-dopamine dependent NMS worsen progressively and culminate at the late stages of PD. Furthermore, some PD specific features could interact negatively with other comorbidities, multiple medication use and frailty - the evaluation of these aspects is important in the creation of personalized management plans in the late stage of PD.

Dementia in long-term Parkinson's disease patients: a multicentre retrospective study

While several studies have investigated the clinical progression of cognitive decline in Parkinson’s disease (PD) patients, there has been a paucity of data on specifically evaluating PD patients with a disease duration of over 20 years. This study retrospectively investigated the frequency of dementia in PD (PDD) patients with a disease duration of over 20 years assessed in research clinics across the UK and Australia. Data from 2327 PD patients meeting the United Kingdom Parkinson’s Disease Society Brain Bank Criteria was pooled. A diagnosis of probable PDD was made according to the Movement Disorder Society Level 1 criteria. Thirty-six participants had a disease duration of at least 20 years. Of the 36 patients, only 7 (19%) were classified as probable PDD. Compared to PD patients without dementia, those with dementia had lower levels of educational attainment and exhibited more severe motor features. Additionally, 34 out of the 36 patients (94%) exhibited a non-tremor dominant phenotype. No significant differences in age, age onset, disease duration, dopaminergic medication use, and sex distribution were observed between PD patients with and without dementia. Findings from the present study suggest that the prevalence of dementia in long-term PD patients may be lower than anticipated and suggest that the trajectory of cognitive decline in PD patients can be different. These findings highlight the need to investigate factors that might affect the outcome of cognitive decline in long-term PD patients, which may lead to the determination of potential modulating factors in the development of dementia in these patients.

Active lifestyles moderate clinical outcomes in autosomal dominant frontotemporal degeneration

INTRODUCTION

Leisure activities impact brain aging and may be prevention targets. We characterized how physical and cognitive activities relate to brain health for the first time in autosomal dominant frontotemporal lobar degeneration (FTLD).

METHODS

A total of 105 mutation carriers (C9orf72/MAPT/GRN) and 69 non-carriers reported current physical and cognitive activities at baseline, and completed longitudinal neurobehavioral assessments and brain magnetic resonance imaging (MRI) scans.

RESULTS

Greater physical and cognitive activities were each associated with an estimated >55% slower clinical decline per year among dominant gene carriers. There was also an interaction between leisure activities and frontotemporal atrophy on cognition in mutation carriers. High-activity carriers with frontotemporal atrophy (-1 standard deviation/year) demonstrated >two-fold better cognitive performances per year compared to their less active peers with comparable atrophy rates.

DISCUSSION

Active lifestyles were associated with less functional decline and moderated brain-to-behavior relationships longitudinally. More active carriers "outperformed" brain volume, commensurate with a cognitive reserve hypothesis. Lifestyle may confer clinical resilience, even in autosomal dominant FTLD.

Socio-economic status and dementia onset among older Japanese: A 6-year prospective cohort study from the Japan Gerontological Evaluation Study

OBJECTIVES

Lower socio-economic status (SES) may be associated with dementia later in life, but there is inconsistent evidence supporting this claim. We aim to examine the association between three SESs (education, job, and income indicators) and dementia onset in older adults.

METHODS

Study design was a 6-year prospective cohort study. Participants included a total of 52 063 community-dwelling adults aged 65 years or older without long-term care needs from the Japan Gerontological Evaluation Study. Outcome variable was dementia onset. Explanatory variables were educational years, the longest job held, and equivalised household income. We performed Cox proportional hazard analysis by gender with multiple imputation.

RESULTS

During the follow-up period, 10.5% of participants acquired dementia. The adjusted risks of dementia incidence of the participants with less than 6 years of education were 1.34 times (95% confidence interval [CI], 1.04-1.73) in men and 1.21 (1.00-1.45) times in women higher than those with more than 13 years of education. Females with less than 1.99 million yen (hazard ratio = 0.83, 0.72-0.96) of equivalised income were less likely to acquire dementia than those with four million yen or higher.

CONCLUSIONS

Educational attainment had a robust impact on dementia onset compared with the other SES factors in both genders of older Japanese people. Securing an education for children could be crucial to prevent dementia later in life. The longest job held was less likely to be risks of dementia incidence, compared with the other two factors.

Early exercise induces long-lasting morphological changes in cortical and hippocampal neurons throughout of a sedentary period of rats

Life experiences at early ages, such as physical activity in childhood and adolescence, can result in long-lasting brain effects able to reduce future risk of brain disorders and to enhance lifelong brain functions. However, how early physical exercise promotes these effects remains unclear. A possible hypothesis is that physical exercise increases the expression of neurotrophic factors and stimulates neuronal growth, resulting in a neural reserve to be used at later ages. Basing our study on this hypothesis, we evaluated the absolute number and morphology of neuronal cells, as well as the expression of growth, proliferation and survival proteins (BDNF, Akt, mTOR, p70S6K, ERK and CREB) in the cerebral cortex and hippocampal formation throughout of a sedentary period of rats who were physically active during youth. To do this, male Wistar rats were submitted to an aerobic exercise protocol from the 21^st to the 60^th postnatal days (P21–P60), and evaluated at 0 (P60), 30 (P90) and 60 (P120) days after the last exercise session. Results showed that juvenile exercise increased, and maintained elevated, the number of cortical and hippocampal neuronal cells and dendritic arborization, when evaluated at the above post-exercise ages. Hippocampal BDNF levels and cortical mTOR expression were found to be increased at P60, but were restored to control levels at P90 and P120. Overall, these findings indicate that, despite the short-term effects on growth and survival proteins, early exercise induces long-lasting morphological changes in cortical and hippocampal neurons even during a sedentary period of rats.

Examining the Reserve Hypothesis in Parkinson's Disease: A Longitudinal Study

BACKGROUND

Whether reserve plays a role in Parkinson's disease (PD) patients has received less attention than in dementia and has been mainly examined in relation with cognitive function.

OBJECTIVE

To investigate whether reserve plays a role in the severity and progression of motor, cognitive, and nonmotor PD symptoms by examining whether education level (proxy of reserve) is associated with baseline performance and rate of progression.

METHODS

We used data from a longitudinal cohort of PD patients (≤5-year disease duration at baseline) annually followed up to 5 years (n = 393; 41% women; mean age = 62.3 years, standard deviation = 10.0; mean disease duration = 2.6 years, standard deviation = 1.5). We examined the relationship of education with time to reach Hoehn and Yahr stage ≥3 using Cox regression and with baseline severity and progression of motor (Movement Disorder Society-Unified Parkinson's Disease Rating Scale parts II and III, gait speed), cognitive (Mini-Mental State Examination), and nonmotor (depression, anxiety, nonmotor symptoms scale, quality of life) symptoms using mixed models.

RESULTS

Education level was not associated with age at onset or diagnosis. Compared with the low-education group, the incidence of Hoehn and Yahr ≥3.0 was 0.42 times lower (95% confidence interval, 0.22-0.82, P = 0.012) in the high-education group. Higher education was associated with better baseline motor function (P < 0.001), but not with the rate of motor decline (P > 0.15). Similar results were observed for cognition. Education was not associated with nonmotor symptoms.

CONCLUSIONS

Higher education is associated with better baseline motor/cognitive function in PD, but not with rate of decline, and with a lower risk of reaching Hoehn and Yahr ≥3 during the follow-up. Our observations are consistent with a passive reserve hypothesis for motor/cognitive symptoms. © 2019 International Parkinson and Movement Disorder Society.

The Association of Cognitive Reserve in Chronic-Phase Functional and Neuropsychological Outcomes Following Traumatic Brain Injury

OBJECTIVE

Examine the association of cognitive reserve (CR) factors (estimated premorbid intelligence quotient [IQ], years of education, and occupational attainment) and traumatic brain injury (TBI) severity with functional and neuropsychological outcomes 1 to 5 years following TBI.

PARTICIPANTS

Patients with mild (N = 58), moderate (N = 25), or severe (N = 17) TBI.

MAIN MEASURES

Cognitive reserve factors (estimated premorbid IQ, years of education, and occupational attainment); neuropsychological test battery; Glasgow Outcome Scale-Extended; Short Form-36 Health Survey.

ANALYSES

Spearman-Brown correlations, linear regression models, and analyses of covariance were used to analyze the relation between CR factors and outcome measures.

RESULTS

Analyses revealed significant relations between estimated premorbid IQ and neuropsychological outcomes (P < .004): California Verbal Learning Test, Wechsler Adult Intelligence Scale-Fourth Edition working memory, Booklet Category Test, Trail Making Test B, and Grooved Pegboard Test. There was also a significant correlation between estimated premorbid IQ and Wechsler Adult Intelligence Scale-Fourth Edition processing speed. Years of education had significant relations with California Verbal Learning Test and Wechsler Adult Intelligence Scale-Fourth Edition working memory and processing speed scores. There were significant differences between TBI severity groups and performance on the Trail Making Test A, Grooved Pegboard Test, and Finger Tapping Test.

CONCLUSIONS

Cognitive reserve factors may be associated with outcomes following TBI. Additional alternatives to TBI severity are needed to help guide rehabilitative planning postinjury.

Quality of education impacts late-life cognition

OBJECTIVES

Screening tests of global cognition detect racial differences in scores even after adjustment for educational attainment. Differential educational environments in adolescence may affect individual cognitive function. This study examines the impact of high school educational quality on late-life cognition among community-dwelling older adults.

METHODS/DESIGN

Data were collected from community-dwelling individuals from the Philadelphia Healthy Brain Aging (PHBA) cohort at the University of Pennsylvania Health System. The present analysis included subjects from the PHBA over the age of 55 years without a diagnosis of Parkinson's disease or dementia, who had attended high school in the City of Philadelphia. Cognition was assessed using the Montreal Cognitive Assessment (MoCA); clinical information was abstracted from the subject's electronic health record. High school information was obtained from the Philadelphia Board of Education. After univariable correlations were defined, we performed stepwise multiple linear regression models to determine the most significant predictors of late-life cognitive status.

RESULTS

A total of 130 subjects meeting inclusion criteria were included in the analysis. Years of education, race, educational level, school district, and financial status were all positively associated with MoCA. Significant negative associations included composite vascular risk, attendance at highly segregated schools, and historical poverty status. In stepwise multiple linear regression modeling, the impact of race on cognition remained significant when educational attainment was added to the model but was no longer significant once segregation status was added.

CONCLUSIONS

This work suggests that academic and community factors beyond years of education have a marked impact on late-life cognition.

Mind the gaps: What we don't know about cognitive impairment in essential tremor

INTRODUCTION

Although the hallmark feature of essential tremor (ET) is tremor, there is growing appreciation that cognitive impairment also occurs, including increased prevalence of mild cognitive impairment (MCI) and increased prevalence and incidence of dementia. With emerging knowledge of ET-cognitive impairment, come fundamental questions regarding its course, bases, predictors and clinical outcomes. Studies in the general population and in Parkinson's disease (PD), a related movement disorder, offer a starting point from which to begin filling these clinically important knowledge gaps.

METHODS

A PubMed search (June 2018) identified articles for this review.

RESULTS

Much of our knowledge of cognitive impairment in ET is of the static condition (e.g., prevalence of cognitive impairment in ET), with nearly no information on its bases, predictors and dynamics (i.e., course, and clinical outcomes). In PD, where such data have been published, rates of cognitive decline and conversion to MCI/dementia are higher than in the general population. Predictors of cognitive change in PD and the general population have also been identified, yet they only partially overlap one another.

CONCLUSION

The predictors and dynamics of cognitive impairment have been investigated fairly extensively in the general population, to a somewhat lesser extent in PD, and are emerging only now in ET. We suggest that longitudinal studies specific to ET are needed, and we outline variables to be considered in these investigations. Increased knowledge of ET-cognitive impairment will facilitate meaningful counseling of patients and their families.

Physical activity mediates the association between striatal dopamine transporter availability and cognition in Parkinson's disease

OBJECTIVE

Associations between cognition and nigrostriatal dopaminergic deficits in Parkinson's disease have been documented in the literature, but are incompletely understood. Here we studied the extent to which physical activity mediates the relationship between striatal dopamine transporter availability and global cognition among patients with Parkinson's disease.

METHODS

Data from 174 patients from a multi-center study were analyzed using regression-based mediation analysis. Striatal dopamine transporter binding ratio (SBR), Physical Activity Scale for Elderly (PASE), and Montreal Cognitive Assessment (MoCA) were used to evaluate patients' dopamine transporter availability (DAT), physical activity, and global cognition respectively at the time of testing. Confidence intervals (CI) of 95% were established using a bootstrapping approach to test the statistical significance of the direct, indirect (i.e., mediation), and total effects of the mediation model.

RESULTS

As hypothesized, the positive mediating effect of physical activity in the association between DAT and global cognition was significant, while adjusting for age (95% CI [0.0030, 0.3942]). Specifically, higher SBRs were positively associated with PASE scores, which in turn, were positively associated with MoCA scores. Secondary analyses revealed a similar positive mediation effect of physical activity for DAT in the caudate and putamen separately (95% CI [0.0377, 0.4231] and [0.0211, 1.1000], respectively).

CONCLUSION

We report that the relationship of dopamine transporter availability with global cognition in Parkinson's disease is mediated by physical activity. Pending further research for specific recommendations, interventions to increase physical activity as tolerated should be considered in patients with Parkinson's disease.

Defining Cognitive Reserve and Implications for Cognitive Aging

PURPOSE OF REVIEW

The aim of this review is to summarize current conceptual models of cognitive reserve (CR) and related concepts and to discuss evidence for these concepts within the context of aging and Alzheimer's disease.

RECENT FINDINGS

Evidence to date supports the notion that higher levels of CR, as measured by proxy variables reflective of lifetime experiences, are associated with better cognitive performance, and with a reduced risk of incident mild cognitive impairment/dementia. However, the impact of CR on longitudinal cognitive trajectories is unclear and may be influenced by a number of factors. Although there is promising evidence that some proxy measures of CR may influence structural brain measures, more research is needed. The protective effects of CR may provide an important mechanism for preserving cognitive function and cognitive well-being with age, in part because it can be enhanced throughout the lifespan. However, more research on the mechanisms by which CR is protective is needed.

Responsiveness to Change of the Montreal Cognitive Assessment, Mini-Mental State Examination, and SCOPA-Cog in Non-Demented Patients with Parkinson's Disease

BACKGROUND

Clinical monitoring of patients with Parkinson's disease (PD) for cognitive decline is an important element of care. The Montreal Cognitive Assessment (MoCA) has been proposed to be a sensitive tool for assessing cognitive impairment in PD. The aim of our study was to compare the responsiveness of the MoCA to decline in cognition to the responsiveness of the Mini Mental State Examination (MMSE) and the Scales for Outcomes of Parkinson's disease-cognition (SCOPA-Cog).

METHODS

PD patients without dementia were enrolled at 6 North American movement disorders centers between 2008 and 2011. Participants received annual evaluations including the MoCA, MMSE, and SCOPA-Cog followed by formal neuropsychological testing. The gold standard for change in cognition was defined as the change on the neuropsychological test scores over the annual assessments. The Reliable Change Method was used to provide an estimate of the probability that a given difference score would be obtained by chance. The sensitivity of the MoCA, MMSE, and SCOPA-Cog to change was quantified using receiver operating characteristics (ROC) curves.

RESULTS

One hundred seventeen patients were included in the analysis. Participants were followed at mean intervals of 11 ± 2 months for a median of 2 (maximum 5) visits. According to the reliable change index, 56 intervals of cognitive testing showed a decline in global cognition. ROC analysis of change in MoCA, MMSE, and SCOPA-Cog global scores compared to gold standard testing found an area under the curve (AUC) of 0.55 (95% CI 0.48-0.62), 0.56 (0.48-0.63), and 0.63 (0.55-0.70) respectively. There were no significant differences in the AUCs across the tests. The sensitivity of the MoCA, MMSE, and SCOPA-Cog to change at various thresholds for decline in scores reached a maximum of 71% for a cut-off of 1 point change on the SCOPA-Cog.

CONCLUSION

Using neuropsychological testing as a gold standard comparator, the performance of the MoCA, MMSE, and SCOPA-Cog for detecting decline in non-demented PD patients over a 1-year interval is poor. This has implications for clinical practice; stable scores may not be taken as reassurance of the absence of cognitive decline.

Neuroprotective effect and mechanism of baicalin on Parkinson's disease model induced by 6-OHDA

OBJECTIVE

This research was aimed to investigate the effects of baicalin on 6-hydroxydopamine (6-OHDA)-induced rat model of Parkinson's disease (PD) and the main mechanism of baicalin based on metabolomics.

METHODS

The rat model of PD was induced by 6-OHDA. The protective effects of baicalin on rat model of PD were evaluated by open field test and rotarod test. The anti-PD efficacy of baicalin was evaluated by examining the morphologic changes of neurons and the level of monoamine neurotransmitters in the striatum, the number and morphology of tyrosine hydroxylase (TH)-positive neurons, and oxidative stress. Combined with metabolomics methods, the pharmacodynamic mechanism of baicalin on PD pathogenesis was also explored.

RESULTS

Baicalin treatment improved the rod time and voluntary movement in rat model of PD (P<0.05) by the open field test and rotarod test. In addition, baicalin also protected from oxidative stress injury (P<0.05), and regulated the content of monoamine neurotransmitters dopamine, 3,4-dihydroxyphenylacetic acid, 5-hydroxytryptamine, and 5-hydroxyindoleacetic acid (P<0.05) and the number and morphology of TH-positive cells in 6-OHDA-induced PD model rats. By metabolomics, multivariate statistical analysis, and receiver operating characteristic curve analysis, we found that two metabolites N-acetyl aspartic acid and glutamic acid had a good diagnostic value. Quantitative analysis of metabolites showed a regulatory function of baicalin.

CONCLUSION

Baicalin has significant protective effect on 6-OHDA-induced PD rats, which may play a protective role through an antioxidant, promoting the release of neurotransmitters and regulating the metabolism of N-acetyl aspartate and glutamate.

The association of cognitive reserve with motor and cognitive functions for different stages of Parkinson's disease

INTRODUCTION

The cognitive reserve (CR) theory has been proposed to account for the mismatch between the degree of neuropathological changes and clinical outcome in dementias. Recently, it has also been applied to Parkinson's disease (PD) with promising results, but mostly just focusing on separate proxy measures of CR, such as education, working and leisure time activities, instead of adopting a more comprehensive approach. Using the Cognitive Reserve Index questionnaire (CRIq), this study examined the association of CR with motor functions and cognition in patients with medium-low (1-9 years) and medium-high (>9 years) PD duration.

METHODS

Fifty patients with PD underwent a neurological and a neuropsychological assessment, comprised of: Unified Parkinson's Disease Rating Scale- section III, Mini-Mental State Examination, Clock-Drawing Test, Rey auditory verbal learning test (immediate and delayed recall trials), Digit Span Forward, Corsi Span Forward, Frontal Assessment Battery, Raven's Colored Progressive Matrices, WAIS similarities subtest, Phonemic Fluency, Semantic Fluency and CRIq.

RESULTS

PD patients with a higher CRIq score showed a reduced motor impairment and a better global cognitive performance when compared to PD patients with a lower CRIq score, with an advantage especially observed on executive functions and short-term memory. The CR effect was even enhanced in the case of longer disease duration, as observed when considering the overall neuropsychological tests performance and non-verbal abstract reasoning in particular. The results obtained when considering education, as a single proxy measure of CR, provided no additional findings, nor did they reveal all the effects yielded by the adoption of the CRI score.

CONCLUSION

Our results support the beneficial role of CR against motor and cognitive dysfunctions in PD and suggest that its protective role may be mostly manifested at the later stages of the disease. A theoretical framework able to explain the different impact of CR on Alzheimer Disease and PD is discussed. Finally, our results stressed the importance of using a comprehensive measure of CR instead of focusing on just one of its proxies.

Cultural engagement and cognitive reserve: museum attendance and dementia incidence over a 10-year period

Theories of cognitive reserve, disuse syndrome and stress have suggested that activities that are mentally engaging, enjoyable and socially interactive could be protective against the development of dementia. Using data from the English Longitudinal Study of Ageing, this study shows that for adults aged 50 and older visiting museums every few months or more was associated with a lower incidence rate of dementia over a 10-year follow-up period compared with less-frequent visiting. This association was independent of demographics, socioeconomic status, health-related variables including sensory impairment, depression, vascular conditions and other forms of community engagement. Visiting museums may be a promising psychosocial activity to support the prevention of dementia.Declaration of interestNone.

Enriched environment elevates expression of growth associated protein-43 in the substantia nigra of SAMP8 mice

An enriched environment protects dopaminergic neurons from 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced neuronal injury, but the underlying mechanism for this is not clear. Growth associated protein-43 (GAP-43) is closely associated with neurite outgrowth and axon regeneration during neural development. We speculate that an enriched environment can reduce damage to dopaminergic neurons by affecting the expression of GAP-43. This study is designed to test this hypothesis. Three-month-old female senescence-accelerated mouse prone 8 (SAMP8) mice were housed for 3 months in an enriched environment or a standard environment. These mice were then subcutaneously injected in the abdomen with 14 mg/kg MPTP four times at 2-hour intervals. Morris water maze testing demonstrated that learning and memory abilities were better in the enriched environment group than in the standard environment group. Reverse-transcription polymerase chain reaction, immunohistochemistry and western blot assays showed that mRNA and protein levels of GAP-43 in the substantia nigra were higher after MPTP application in the enriched environment group compared with the standard environment group. These findings indicate that an enriched environment can increase GAP-43 expression in SAMP8 mice. The upregulation of GAP-43 may be a mechanism by which an enriched environment protects against MPTP-induced neuronal damage.

Coriolus versicolor biomass increases dendritic arborization of newly-generated neurons in mouse hippocampal dentate gyrus

Brain cognitive reserve refers to the ability of the brain to manage different challenges that arise throughout life, making it resilient to neuropathology. Hippocampal adult neurogenesis has been considered to be a relevant contributor for brain cognitive reserve and brain plasticity. Coriolus versicolor (CV), a common healthful mushroom, has been receiving increasing attention by its antitumoral, anti-inflammatory, antioxidant, antibacterial, and immunomodulatory properties, including in the hippocampus. Herein, we evaluated whether CV biomass oral administration for 2.5 months enhances hippocampal neurogenic reserve under normal/physiological conditions, by quantifying hippocampal dentate gyrus (DG) granular cell layer (GCL) and subgranular zone (SGZ) volumes, proliferation, number and dendritic complexity features of hippocampal newly-generated neurons. We also analyzed β-catenin levels in DG newly-generated immature neurons, because it plays a major role in neurogenesis. Although no differences were observed in the volume of GCL and SGZ layers, in proliferation and in the number of newly-generated neurons of controls and CV-administered mice, we found that CV administration promotes a significant increase in dendritic length and branching and total dendritic volume of immature neurons, suggesting a positive effect of oral CV administration in the hippocampal neurogenic reserve. We also observed that β-catenin levels are increased both in the nucleus and cytoplasm of DG immature neurons, suggesting that Wnt/β-catenin signalling may play an important role in the CV positive effect on the differentiation of these cells. These data unveil a so far unexplored neurogenic potential of CV supplementation, which emerges as a possible preventive strategy for different neurological conditions.

The role of cognitive reserve in cognitive aging: what we can learn from Parkinson's disease

Parkinson's disease (PD) typically occurs in elderly people and some degree of cognitive impairment is usually present. Cognitive reserve (CR) theory was proposed to explain the discrepancy between the degree of brain pathologies and clinical manifestations. We administered a comprehensive neuropsychological battery to 35 non-demented participants affected by PD. All participants underwent also the Cognitive Reserve Index questionnaire and the Brief Intelligence Test as proxies for CR. Relationships between CR and cognitive performance were investigated by linear regression analyses, adjusting for significant confounding factors. At linear regression analyses, higher CR scores were independently associated with a better performance on Word Fluency (p ≤ 0.04) and Digit Span (backward) (p ≤ 0.02); no associations were observed between CR and other cognitive tests. Our data provide empirical support to the relation between CR and cognitive impairment in PD. In particular, this study suggests that CR may have greater effects on the cognitive areas mostly affected in PD as executive functions.

Single-subject SPM FDG-PET patterns predict risk of dementia progression in Parkinson disease

OBJECTIVE

To evaluate the statistical parametric mapping (SPM) procedure for fluorodeoxyglucose (FDG)-PET imaging as a possible single-subject marker of progression to dementia in Parkinson disease (PD).

METHODS

Fifty-four consecutive patients with PD without dementia (age at onset of 59.9 ± 10.1 years, disease duration of 5.3 ± 3.4 years) entered the study. The patients underwent an extensive motor and cognitive assessment and a single-subject FDG-PET SPM evaluation at baseline. A 4-year follow-up provided disease progression and dementia diagnosis.

RESULTS

The FDG-PET SPM was evaluated by 2 expert raters allowing the identification of a "typical PD pattern" in 29 patients, whereas 25 patients presented with "atypical patterns," namely, dementia with Lewy bodies (DLB)-like (n = 12), Alzheimer disease (AD)-like (n = 6), corticobasal syndrome (CBS)-like (n = 5), and frontotemporal dementia (FTD)-like (n = 2). At 4-year follow-up, 13 patients, all showing atypical brain metabolic patterns at baseline, progressed to dementia (PD dementia). The DLB- and AD-like SPM patterns were the best predictor for incident dementia (p < 0.005, sensitivity 85%, specificity 88%), independently from demographics or cognitive baseline classification.

CONCLUSIONS

This study suggests that FDG-PET SPM at the single-subject level might help in identifying patients with PD at risk of developing dementia.

Predicting cognitive function of the Malaysian elderly: a structural equation modelling approach

OBJECTIVES

The aim of this study was to identify the predictors of elderly's cognitive function based on biopsychosocial and cognitive reserve perspectives.

METHOD

The study included 2322 community-dwelling elderly in Malaysia, randomly selected through a multi-stage proportional cluster random sampling from Peninsular Malaysia. The elderly were surveyed on socio-demographic information, biomarkers, psychosocial status, disability, and cognitive function. A biopsychosocial model of cognitive function was developed to test variables' predictive power on cognitive function. Statistical analyses were performed using SPSS (version 15.0) in conjunction with Analysis of Moment Structures Graphics (AMOS 7.0).

RESULTS

The estimated theoretical model fitted the data well. Psychosocial stress and metabolic syndrome (MetS) negatively predicted cognitive function and psychosocial stress appeared as a main predictor. Socio-demographic characteristics, except gender, also had significant effects on cognitive function. However, disability failed to predict cognitive function.

CONCLUSION

Several factors together may predict cognitive function in the Malaysian elderly population, and the variance accounted for it is large enough to be considered substantial. Key factor associated with the elderly's cognitive function seems to be psychosocial well-being. Thus, psychosocial well-being should be included in the elderly assessment, apart from medical conditions, both in clinical and community setting.

The effects of lifelong cognitive lifestyle on executive function in older people with Parkinson's disease

OBJECTIVE

Active lifelong cognitive lifestyles increase cognitive reserve and have beneficial effects on global cognition, cognitive decline and dementia risk in Parkinson's disease (PD). Executive function is particularly impaired even in early PD, and this impacts on quality of life. The effects of lifelong cognitive lifestyle on executive function in PD have not been studied previously. This study examined the association between lifelong cognitive lifestyle, as a proxy measure of cognitive reserve, and executive function in people with PD.

METHODS

Sixty-nine people diagnosed with early PD without dementia were recruited as part of the Bilingualism as a protective factor in Age-related Neurodegenerative Conditions study. Participants completed a battery of tests of executive function. The Lifetime of Experiences Questionnaire was completed as a comprehensive assessment of lifelong cognitive lifestyle. Non-parametric correlations compared clinical measures with executive function scores. Cross-sectional analyses of covariance were performed comparing the performance of low and high cognitive reserve groups on executive function tests.

RESULTS

Correlational analyses showed that better executive function scores were associated with younger age, higher levodopa dose and higher Lifetime of Experiences Questionnaire scores. Higher cognitive reserve was associated with better motor function, but high and low cognitive reserve groups did not differ in executive function.

CONCLUSIONS

Cognitive reserve, although associated with global cognition, does not appear to be associated with executive function. This differential effect may reflect the specific cognitive profile of PD. The long-term effects of cognitive reserve on executive function in PD require further exploration. Copyright © 2017 John Wiley & Sons, Ltd.

APOE, thought disorder, and SPARE-AD predict cognitive decline in established Parkinson's disease

BACKGROUND

People with PD are at high risk of developing cognitive impairment and dementia. Cross-sectional studies have identified candidate biomarkers associated with cognitive decline. However, longitudinal studies on this topic are rarer, and few have investigated the use of biomarker panels encompassing multiple modalities. The objective of this study was to find baseline predictors of cognitive decline in longitudinally followed, nondemented Parkinson's disease patients.

METHODS

We performed a prospective cohort study of 100 PD patients with a median disease duration of 6.4 years. All participants were nondemented at baseline. We examined 16 baseline biomarkers from clinical, genetic, biochemical, and MRI-based imaging modalities for their association with longitudinal cognitive decline for up to 8 years. We investigated biomarkers individually, as well as in a multivariate linear mixed-effects model encompassing multimodal biomarkers, with change in the Mattis Dementia Rating Scale-2 over time as the primary outcome. Annual consensus process-derived cognitive diagnosis was used for Cox proportional hazards modeling of risk for cognitive decline.

RESULTS

In multivariate analysis, the presence of the APOE E4 allele, thought disorder, and an Alzheimer's disease pattern of brain atrophy (spatial pattern of abnormality for recognition of early Alzheimer's disease index) best predicted cognitive decline, with APOE E4 genotype exerting the greatest effect. The presence of the APOE E4 allele was associated with a 3.5 times higher risk of worsening cognitive diagnosis over time (HR, 3.53; 95% CI, 1.52-8.24; P < 0.05). The APOE genotype effect was not specific to any Mattis Dementia Rating Scale-2 domain.

CONCLUSIONS

Our results confirm the importance of Alzheimer's disease biomarkers as risk factors for cognitive decline in established Parkinson's disease. © 2017 International Parkinson and Movement Disorder Society.