A dynamic computational model of the parallel circuit on the basal ganglia-cortex associated with Parkinson's disease dementia

The cognitive impairment will gradually appear over time in Parkinson's patients, which is closely related to the basal ganglia-cortex network. This network contains two parallel circuits mediated by putamen and caudate nucleus, respectively. Based on the biophysical mean-field model, we construct a dynamic computational model of the parallel circuit in the basal ganglia-cortex network associated with Parkinson's disease dementia. The simulated results show that the decrease of power ratio in the prefrontal cortex is mainly caused by dopamine depletion in the caudate nucleus and is less related to that in the putamen, which indicates Parkinson's disease dementia may be caused by a lesion of the caudate nucleus rather than putamen. Furthermore, the underlying dynamic mechanism behind the decrease of power ratio is investigated by bifurcation analysis, which demonstrates that the decrease of power ratio is due to the change of brain discharge pattern from the limit cycle mode to the point attractor mode. More importantly, the spatiotemporal course of dopamine depletion in Parkinson's disease patients is well simulated, which states that with the loss of dopaminergic neurons projecting to the striatum, motor dysfunction of Parkinson's disease is first observed, whereas cognitive impairment occurs after a period of onset of motor dysfunction. These results are helpful to understand the pathogenesis of cognitive impairment and provide insights into the treatment of Parkinson's disease dementia.

The Impact of Sex-Specific Survival on the Incidence of Dementia in Parkinson's Disease

OBJECTIVE

The aim of our study is to analyze sex-specific patterns of Parkinson's disease dementia (PDD) incidence. We are investigating the extent to which sex differences in survival after initial Parkinson's disease (PD) diagnosis influence differences in PDD risk among PD patients.

METHODS

We used a random sample of German longitudinal health claims data of persons ages 50+ (2004-2019; n = 250,000) and identified new PD cases ages 65+ who were followed-up for a PDD diagnosis or death between 2006 and 2017. We performed Cox and competing-risk regression models, with death as competing event, to calculate PDD hazard ratios (HR) adjusted for age at PD onset, PD severity as measured by the modified Hoehn and Yahr (HY) scale, comorbidities, and medications.

RESULTS

Of 2195 new PD cases, 602 people died before PDD and 750 people developed PDD by the end of 2017. The adjusted risk of PDD differs by sex, with men having a higher PDD risk than women. When accounting for death, men and women do not differ in their PDD risk (HR = 1.02, P = 0.770). Sex-specific analyses showed significant age and severity effects in women (age: HR = 1.05, P < 0.001; HY 3-5 vs. 0-2.5: HR = 1.46, P = 0.011), but not in men.

CONCLUSION

Older age at first PD diagnosis and higher disease severity increase PDD risk, but this association is attenuated for PD men when controlling for death. This implies that the most frail PD men die rapidly before receiving a dementia diagnosis, whereas women with PD survive at higher rates, regardless of their age at onset and disease severity. © 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Sleep disorders in Lewy body dementia: Mechanisms, clinical relevance, and unanswered questions

In Lewy body dementia (LBD), disturbances of sleep and/or arousal including insomnia, excessive daytime sleepiness, rapid eye movement (REM) sleep behavior disorder, obstructive sleep apnea, and restless leg syndrome are common. These disorders can each exert a significant negative impact on both patient and caregiver quality of life; however, their etiology is poorly understood. Little guidance is available for assessing and managing sleep disorders in LBD, and they remain under-diagnosed and under-treated. This review aims to (1) describe the specific sleep disorders which occur in LBD, considering their putative or potential mechanisms; (2) describe the history and diagnostic process for these disorders in LBD; and (3) summarize current evidence for their management in LBD and consider some of the ongoing and unanswered questions in this field and future research directions.

Atypical brain FDG-PET patterns increase the risk of long-term cognitive and motor progression in Parkinson's disease

INTRODUCTION

Brain hypometabolism patterns have been previously associated with cognitive decline in Parkinson's disease (PD). Our aim is to evaluate the impact of single-subject fluorodeoxyglucose (FDG)-PET brain hypometabolism on long-term cognitive and motor outcomes in PD.

METHODS

Forty-nine non-demented PD patients with baseline brain FDG-PET data underwent an extensive clinical follow-up for 8 years. The ability of FDG-PET to predict long-term cognitive and motor progression was evaluated using Cox regression and mixed ANCOVA models.

RESULTS

Participants were classified according to FDG-PET pattern in PD with typical (n = 26) and atypical cortical metabolism (n = 23). Patients with atypical brain hypometabolic patterns showed higher incidence of dementia (60% vs 3%; HR = 18.3), hallucinations (56% vs 7%, HR = 7.3) and faster motor decline compared to typical pattern group.

CONCLUSION

This study argues for specific patterns of FDG-PET cortical hypometabolism in PD as a prognostic marker for long term cognitive and motor outcomes at single-subject level.

Cognitive and Motor Decline in Dementia with Lewy Bodies and Parkinson's Disease Dementia

Background

There is a need to better understand the rate of cognitive and motor decline of Dementia with Lewy bodies (DLB) and Parkinson's disease Dementia (PDD).

Objectives

To compare the rate of cognitive and motor decline in patients with DLB and PDD from the E-DLB Consortium and the Parkinson's Incidence Cohorts Collaboration (PICC) Cohorts.

Methods

The annual change in MMSE and MDS-UPDRS part III was estimated using linear mixed regression models in patients with at least one follow-up (DLB n = 837 and PDD n = 157).

Results

When adjusting for confounders, we found no difference in the annual change in MMSE between DLB and PDD (-1.8 [95% CI -2.3, -1.3] vs. -1.9 [95% CI -2.6, -1.2] [P = 0.74]). MDS-UPDRS part III showed nearly identical annual changes (DLB 4.8 [95% CI 2.1, 7.5]) (PDD 4.8 [95% CI 2.7, 6.9], [P = 0.98]).

Conclusions

DLB and PDD showed similar rates of cognitive and motor decline. This is relevant for future clinical trial designs.

Independent effect of cardiometabolic syndromes and depression on dementia in Parkinson's disease: A 12-year longitudinal follow-up study of a nationwide cohort

BACKGROUND

We aimed to investigate the incidence rate of Parkinson's disease dementia (PDD) according to age and disease duration by sex. Furthermore, we explored the effect of each cardiometabolic syndrome and depression on the incidence of PDD.

METHODS

Using data from the Korean National Health Insurance Service, 79,622 patients with de novo Parkinson's disease (PD) aged ≥40 years between January 2002 and December 2010 were followed to December 2019. We analyzed the incidence of PDD according to age at PD diagnosis and disease duration. To determine cardiometabolic syndromes and depression that affected PDD, we used Fine and Gray competing regression after controlling for age and sex.

RESULTS

During the 12.5-year follow-up period, the incidence of PDD increased with age at PD diagnosis (0.81-45.31 per 1000 person-years among those aged 40-44 and over 80 years, respectively) and longer disease duration (22.68 per 1000 person-years in 1-2 years to 34.16 per 1000 person-years in 15-16 years). Hypertension (subdistribution hazard ratio [SHR] = 1.11; 95% confidence interval [CI] 1.07-1.16), diabetes (SHR = 1.09; 95% CI 1.05-1.14), dyslipidemia (SHR = 1.15; 95% CI 1.11-1.20), and depression (SHR = 1.36; 95% CI 1.30-1.41) independently increased the risk for PDD.

CONCLUSIONS

Our findings provide insights into cardiometabolic syndromes as modifiable risk factors for incident PDD. Furthermore, our results will help in designing public health policies with respect to controlling cardiometabolic syndromes and depression to prevent incident PDD in patients with PD.

In Vivo 18 F-Florzolotau Tau Positron Emission Tomography Imaging in Parkinson's Disease Dementia

BACKGROUND

Tau pathology is observed during autopsy in many patients with Parkinson's disease dementia (PDD). Positron emission tomography (PET) imaging using the tracer ¹⁸ F-florzolotau has the potential to capture tau accumulation in the living brain.

OBJECTIVE

The aim was to describe the results of ¹⁸ F-florzolotau PET/CT (computed tomography) imaging in patients with PDD.

METHODS

Ten patients with PDD, 9 with Parkinson's disease with normal cognition (PD-NC), and 9 age-matched healthy controls (HCs) were enrolled. Clinical assessments and ¹⁸ F-florzolotau PET/CT imaging were performed.

RESULTS

¹⁸ F-Florzolotau uptake was significantly higher in the cortical regions of patients with PDD compared with both PD-NC and HCs, especially in the temporal lobe. Notably, ¹⁸ F-florzolotau uptake in the occipital lobe of patients with PDD showed a significant correlation with cognitive impairment as reflected by Mini-Mental State Examination (MMSE) scores.

CONCLUSIONS

¹⁸ F-Florzolotau PET imaging can effectively capture the occurrence of tau pathology in patients with PDD, which was also linked to MMSE scores. © 2022 International Parkinson and Movement Disorder Society.

Consistent Abnormalities in Metabolic Patterns of Lewy Body Dementias

BACKGROUND

Whether dementia with Lewy bodies (DLB) and Parkinson's disease (PD) dementia (PDD) represent the same disease, distinct entities, or conditions within the same spectrum remains controversial.

OBJECTIVE

The objective of this study was to provide new insight into this debate by separately identifying disease-specific metabolic patterns and comparing them with each other and with previously established PD-related pattern (PDRP).

METHODS

Patients with DLB (n = 67), patients with PDD (n = 50), and healthy control subjects (HCs; n = 15) with brain ¹⁸ F-fluorodeoxyglucose positron emission tomography were enrolled as cohorts A and B for pattern identification and validation, respectively. Patients with PD (n = 30) were included for discrimination. Twenty-one participants had two scans. The principal component analysis was applied for pattern identification (DLB-related pattern [DLBRP], PDD-related pattern [PDDRP]). Similarities and differences among three patterns were assessed by pattern topography, pattern expression, clinical correlations cross-sectionally, and pattern expression changes longitudinally.

RESULTS

DLBRP and PDDRP shared highly similar topographies, with relative hypometabolism mainly in the middle temporal gyrus, middle occipital gyrus, lingual gyrus, precuneus, cuneus, angular gyrus, superior and inferior parietal gyrus, middle and inferior frontal gyrus, cingulate, and caudate, and relative hypermetabolism in the cerebellum, putamen, thalamus, precentral/postcentral gyrus, and paracentral lobule, which were more extensive than the PDRP. Patients with DLB and PDD could not be distinguished successfully by any pattern, but patients with PD were easily recognized, especially by DLBRP and PDDRP. The pattern expression of DLBRP and PDDRP showed similar efficacy in cross-sectional disease severity assessment and longitudinal progression monitoring.

CONCLUSIONS

The consistent abnormalities in metabolic patterns of DLB and PDD might underline the potential continuum across the clinical spectrum from PD to DLB. © 2022 International Parkinson and Movement Disorder Society.

A modified version of the interlocking finger test as a bedside screening test for visuospatial deficits and dementia in Parkinson's disease

INTRODUCTION

Objective of this study was to examine if the Interlocking Finger Test (ILFT) is a suitable bedside screening test for visuospatial functions and/or dementia in Parkinson's disease (PD) patients aiming to facilitate the diagnosis of a dementia syndrome associated with posterior cortical and temporal lobe dysfunction according to the dual syndrome hypothesis (frontostriatal vs. posterior cortical cognitive impairment).

METHODS

Forty-seven PD patients were assessed with the ILFT and an extensive cognitive test battery. The ILFT was carried out in the original version as well as in three modified versions of the test including a fifth figure and/or a more complex rating system, leading to four different ILFT scores (named after the maximum achievable scoring result: ILFT 4, ILFT 5, ILFT 12, and ILFT 15). We conducted a correlation analysis to reveal associations between the ILFT scores and cognitive as well as motor impairments. Receiver operating curve (ROC) analyses were calculated to evaluate the ability of the ILFT scores to predict visuospatial impairments and dementia.

RESULTS

ILFT scores correlated significantly with global cognition, visuospatial functions, memory, attention, and age (p < .0125) but not with executive functions, language, education, depression, and motor impairment. The ROC analyses revealed ILFT 15 as best predictor for visuospatial deficits and dementia with an area under the curve of .82 and .88, respectively.

CONCLUSION

The ILFT is suitable for detecting symptoms of the posterior cortical degeneration syndrome according to the dual syndrome hypothesis. We recommend the use of the modified test version ILFT 15.

Age-Stratified Risk of Dementia in Parkinson's Disease: A Nationwide, Population-Based, Retrospective Cohort Study in Taiwan

Introduction: Parkinson's disease (PD) manifests with dominant motor symptoms and a wide range of non-motor symptoms (NMS). Dementia is one of the most disabling and exhausting NMS throughout the clinical course. We conducted a population-based, age-stratified, retrospective cohort study to investigate the incidence rate and risk of dementia of patients with newly diagnosed PD, and linked to the clinicopathological PD subtypes.

Methods: Patients with newly diagnosed PD (PD group, n = 760) and control subjects (non-PD group, n = 3,034) were selected from the Taiwan's National Health Insurance Research Database from January 2001 to December 2005. The dementia incidence rate and dementia-free survival rate were calculated.

Results: The overall dementia incidence rate was 17.5 and 5.7 per 1,000 person-years in PD and non-PD groups, respectively. The PD group had a significantly higher overall risk of dementia than controls (p < 0.001). The younger PD patients had a lower dementia incidence rate than the older PD patients, but a higher dementia risk compared to the same age of controls (<60 years, adjusted HR 6.55, 95% CI 1.56–27.48, p = 0.010). The dementia-free survival rate was significantly lower in the PD group compared to the non-PD group during follow-up (p < 0.001).

Conclusion: In our study, the older age of onset in PD patients resulted in a higher incidence rate of dementia. In the young age of PD patients, the incidence rate of dementia was lower than the older PD patients, but the dementia risk was higher than controls of the same age. These findings possibly implied that there were different pathogenesis and pathologies causing dementia in younger and older PD patients.

Elevation of inactive cleaved annexin A1 in the neocortex is associated with amyloid, inflammatory and apoptotic markers in neurodegenerative dementias

Inflammation is usually a tightly regulated process whose termination by mediators including Annexin A1 (AnxA1) results in the resolution of inflammatory responses. In neurodegenerative dementias, chronic neuroinflammation, along with accumulation of aggregated β-amyloid (Aβ) peptides and apoptosis, has long been recognized to be a pathological hallmark; but it is unclear whether a failure of inflammation resolution contributes to this pathophysiological process. In this study, we measured AnxA1 immunoreactivities in postmortem neocortex (Brodmann areas BA9 and BA40) of well characterized Alzheimer's disease (AD), Parkinson disease dementia (PDD) and dementia with Lewy bodies (DLB) patients as well as aged controls. Inactive cleaved AnxA1 was found to be elevated in AD and DLB in BA40. Levels of cleaved AnxA1 also positively correlated with amyloidogenic brain Aβ, anti-inflammatory markers such as IL10 and IL13, as well as with the pro-apoptotic marker cleaved caspase-3 in BA40. Our findings suggest that elevated cleaved AnxA1 in neurodegenerative dementias may reflect a failure of inflammation resolution in certain regions of the diseased brain, and also support a mechanistic link between AnxA1 and amyloid pathology, neuroinflammation and apoptosis.

Antimuscarinic Anticholinergic Medications in Parkinson Disease: To Prescribe or Deprescribe?

The relative importance of antimuscarinic anticholinergic medications for Parkinson's disease (PD) declined after the introduction of levodopa, such that anticholinergic medications are now much more likely to be prescribed for clinical indications other than parkinsonism. Recent studies have found an association between anticholinergic medication exposure and future risk of dementia in older individuals and those with PD. These findings provide a further reason to avoid the use of anticholinergic medications to treat motor symptoms of PD. More importantly, they raise the question of whether one of the goals of PD treatment should be to deprescribe all medications with anticholinergic properties, regardless of their indication, to reduce dementia risk. In this review, we discuss the use of anticholinergic medications in PD, the evidence supporting the association between anticholinergic medications and future dementia risk, and the potential implications of these findings for clinical care in PD.

[Therapeutic trials in dementia with Lewy bodies: a systematic review of the literature]

BACKGROUND

Cognitive diseases with Lewy bodies occur in two forms: dementia with Lewy bodies (DLB) and Parkinson's disease dementia (PDD), which follows the progression of Parkinson's disease. There is currently no curative treatment for these cognitive diseases with Lewy bodies. Therapeutic trials in DLB are rare, due to the recent description of the disease as well as its first international diagnostic criteria (1996).

METHOD

This article proposes a synthesis of the therapeutic trials carried out in DLB in the last 5 years, including PDD patients with DLB patients, using the Clinicaltrials.gov and Pubmed.gov databases.

RESULTS

We identified 35 therapeutic trials on Clinical Trials and 14 on PubMed. According to our temporal criteria, 21 trials were analyzed. Among the 11 completed trials with reported results, two molecules showed positive results: two trials with zonisamide (phase 2 and 3) showed a gain on parkinsonism and one trial with neflamapimod (phase 2) a gain on cognition and walking.

CONCLUSION

In recent years, there has been an increase in the therapeutic research effort in DLB, which is consistent with the prevalence of this disease - approximately 200,000 patients in France. Compared to other cognitive neurodegenerative diseases, therapeutic research is largely insufficient, whereas the proportion of positive trials is important. An effective disease modifying would have strong consequences for the patient and the relatives.

Olfaction, cholinergic basal forebrain degeneration, and cognition in early Parkinson disease

INTRODUCTION

Impaired olfaction and reduced cholinergic nucleus 4 (Ch4) volume both predict greater cognitive decline in Parkinson's disease (PD). We examined the relationship between olfaction, longitudinal change in cholinergic basal forebrain nuclei and their target regions, and cognition in early PD.

METHODS

We analyzed a cohort of 97 PD participants from the Parkinson's Progression Markers Initiative with brain MRIs at baseline, 1 year, 2 years, and 4 years. Using probabilistic maps, regional grey matter density (GMD) was calculated for Ch4, cholinergic nuclei 1, 2, and 3 (Ch123), and their target regions.

RESULTS

Baseline University of Pennsylvania Smell Identification Test score correlated with change in GMD of all regions of interest (all p < 0.05). Rate of change of Ch4 GMD was correlated with rate of change of Ch123 (p = 0.034), cortex (p = 0.001), and amygdala GMD (p < 0.001), but not hippocampus GMD (p = 0.38). Rate of change of Ch123 GMD was correlated with rate of change of cortex (p = 0.001) and hippocampus (p < 0.001), but not amygdala GMD (p = 0.133). In a linear regression model including change in GMD of all regions of interest and age as predictors, change in cortex GMD (βˆ_slope= 38.2; 95 % CI: [0.47, 75.9]) and change in hippocampus GMD (βˆ_slope= 24.8; 95 % CI: [0.80, 48.8]) were significant predictors of Montreal Cognitive Assessment score change over time.

CONCLUSION

Impaired olfaction is associated with degeneration of the cholinergic basal forebrain and bilateral cortex, amygdala, and hippocampus in PD. The relationship between impaired olfaction and cognitive decline may be mediated by greater atrophy of the cortex and hippocampus.

Exploring the experiences of living with Lewy body dementia: An integrative review

AIM

Lewy body dementia is a common neurodegenerative dementia with unique challenges in managing day-to-day life. A more in-depth multifaceted picture of the Lewy body dementia lived experience will enable identification of best practice and future research direction. The review aim was to explore experiences of people living with Lewy body dementia and their family carers.

DESIGN

Integrative review method informed by Whittemore and Knafl, supported by the information retrieval framework PALETTE. A convergent integrated approach enabled synthesis of key findings and theme identification.

DATA SOURCES

Medline, CINAHL, PsycINFO, AMED, and ALOIS databases were systematically searched to find studies published between 1995 and 2020.

REVIEW METHODS

Twenty-six articles from twenty studies were synthesized (from 1583 retrieved). Quality and relevance were appraised using the Mixed-Methods Appraisal Tool and Gough's 'Weight of Evidence' framework. Data management was supported by ATLAS.ti 8 and COVIDENCE software.

RESULTS

Four themes were identified: living with an uncertain diagnosis and prognosis; fear of the now - worry for the future; living with behavioural and psychiatric symptoms; and maintaining a social and emotional life. People reported difficulty finding information and support around diagnosis, disease progression and managing complex symptoms. The result is increased caregiver burden, grief and stress and reduced quality of life.

CONCLUSION

Delayed diagnosis and complex symptom burden means people are not getting the timely support and information they need to live and die well. Current evidence is largely quantitative, with a focus on family caregiver burden and unmet need. The challenge remains in how to capture a more holistic picture of the lived experience for people living with Lewy body dementia and those who care for them.

IMPACT

This review highlighted current knowledge and identified gaps in exploring the lived experience for people with Lewy body dementia and their families.

Visual Dysfunction Predicts Cognitive Impairment and White Matter Degeneration in Parkinson's Disease

BACKGROUND

Visual dysfunction predicts dementia in Parkinson's disease (PD), but whether this translates to structural change is not known. The objectives of this study were to identify longitudinal white matter changes in patients with Parkinson's disease and low visual function and also in those who developed mild cognitive impairment.

METHODS

We used fixel-based analysis to examine longitudinal white matter change in PD. Diffusion MRI and clinical assessments were performed in 77 patients at baseline (22 low visual function/55 intact vision and 13 PD-mild cognitive impairment/51 normal cognition) and 25 controls and again after 18 months. We compared microstructural changes in fiber density, macrostructural changes in fiber bundle cross-section and combined fiber density and cross-section, across white matter, adjusting for age, sex, and intracranial volume.

RESULTS

Patients with PD and visual dysfunction showed worse cognitive performance at follow-up and were more likely to develop mild cognitive impairment compared with those with normal vision (P = 0.008). Parkinson's with poor visual function showed diffuse microstructural and macrostructural changes at baseline, whereas those with mild cognitive impairment showed fewer baseline changes. At follow-up, Parkinson's with low visual function showed widespread macrostructural changes, involving the fronto-occipital fasciculi, external capsules, and middle cerebellar peduncles bilaterally. No longitudinal change was seen in those with mild cognitive impairment at baseline or converters, even when the 2 groups were combined.

CONCLUSION

Parkinson's patients with poor visual function show increased white matter damage over time, providing further evidence for visual function as a marker of imminent cognitive decline. © 2021 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Widespread Decreases in Cerebral Copper Are Common to Parkinson's Disease Dementia and Alzheimer's Disease Dementia

Several studies of Parkinson's disease (PD) have reported dysregulation of cerebral metals, particularly decreases in copper and increases in iron in substantia nigra (SN). However, few studies have investigated regions outside the SN, fewer have measured levels of multiple metals across different regions within the same brains, and there are no currently-available reports of metal levels in Parkinson's disease dementia (PDD). This study aimed to compare concentrations of nine essential metals across nine different brain regions in cases of PDD and controls. Investigated were: primary motor cortex (MCX); cingulate gyrus (CG); primary visual cortex (PVC); hippocampus (HP); cerebellar cortex (CB); SN; locus coeruleus (LC); medulla oblongata (MED); and middle temporal gyrus (MTG), thus covering regions with severe, moderate, or low levels of neuronal loss in PDD. Levels of eight essential metals and selenium were determined using an analytical methodology involving the use of inductively-coupled plasma mass spectrometry (ICP-MS), and compared between cases and controls, to better understand the extent and severity of metal perturbations. Findings were also compared with those from our previous study of sporadic Alzheimer's disease dementia (ADD), which employed equivalent methods, to identify differences and similarities between these conditions. Widespread copper decreases occurred in PDD in seven of nine regions (exceptions being LC and CB). Four PDD-affected regions showed similar decreases in ADD: CG, HP, MTG, and MCX. Decreases in potassium and manganese were present in HP, MTG and MCX; decreased manganese was also found in SN and MED. Decreased selenium and magnesium were present in MCX, and decreased zinc in HP. There was no evidence for increased iron in SN or any other region. These results identify alterations in levels of several metals across multiple regions of PDD brain, the commonest being widespread decreases in copper that closely resemble those in ADD, pointing to similar disease mechanisms in both dementias.

Differentiating dementia with Lewy bodies from Alzheimer's disease and Parkinson's disease dementia: an update on imaging modalities

Dementia with Lewy bodies is the second most common cause of neurodegenerative dementia after Alzheimer's disease. Dementia with Lewy bodies can provide a diagnostic challenge due to the frequent overlap of clinical signs with other neurodegenerative conditions, namely Parkinson's disease dementia, and Alzheimer's disease. Part of this clinical overlap is due to the neuropathological overlap. Dementia with Lewy bodies is characterized by the accumulation of aggregated α-synuclein protein in Lewy bodies, similar to Parkinson's disease and Parkinson's disease dementia. However, it is also frequently accompanied by aggregation of amyloid-beta and tau, the pathological hallmarks of Alzheimer's disease. Neuroimaging is central to the diagnostic process. This review is an overview of both established and evolving imaging methods that can improve diagnostic accuracy and improve management of this disorder.

Exploring Bottom-Up Visual Processing and Visual Hallucinations in Parkinson's Disease With Dementia

Visual hallucinations (VH) are a common symptom of Parkinson's disease with dementia (PDD), affecting up to 65% of cases. Integrative models of their etiology posit that a decline in executive control of the visuo-perceptual system is a primary mechanism of VH generation. The role of bottom-up processing in the manifestation of VH in this condition is still not clear although visual evoked potential (VEP) differences have been associated with VH at an earlier stage of PD. Here we compared the amplitude and latency pattern reversal VEPs in healthy controls (n = 21) and PDD patients (n = 34) with a range of VH severities. PDD patients showed increased N2 latency relative to controls, but no significant differences in VEP measures were found for patients reporting complex VH (CVH) (n = 17) compared to those without VH. Our VEP findings support previous reports of declining visual system physiology in PDD and some evidence of visual system differences between patients with and without VH. However, we did not replicate previous findings of a major relationship s between the integrity of the visual pathway and VH.

Altered awareness of cognitive and neuropsychiatric symptoms in Parkinson's disease and Dementia with Lewy Bodies: A systematic review

OBJECTIVES

Altered awareness of cognitive and neuropsychiatric symptoms is a common feature of neurodegeneration, which can significantly impact on quality of life, medication concordance and personal safety. Elucidating how awareness is affected by common alpha-synucleinopathies therefore has significant clinical relevance. We performed a systematic review of the literature on awareness of cognitive and neuropsychiatric symptoms in Parkinson's disease and Dementia with Lewy Bodies.

METHODS

Searches of PubMed and Web of Science were carried out, using keywords and MeSH subheadings, limited to papers in English dealing with humans. The terms "Parkinson's" or "Lewy body" were used to denote the disease of interest, combined with either "agnosia", "anosognosia", "insight", "metacognition", or "neuropsychology" to denote the neuropsychological area of interest.

RESULTS

21 publications investigating awareness of cognitive symptoms, and 18 publications on awareness of neuropsychiatric symptoms were identified. The large majority focused on Parkinson's disease rather than Dementia with Lewy Bodies. Cognitively intact people with Parkinson's disease may over-report cognitive symptoms, whilst those with cognitive impairment under-report symptoms. Awareness of neuropsychiatric symptoms is likely to decline over time, particularly in those with progressive cognitive impairment.

CONCLUSIONS

Altered awareness of cognitive and neuropsychiatric symptoms is common in Parkinson's disease. Symptom awareness varies significantly between individuals, and appears to be influenced by mood and global cognitive functioning, with executive functioning specifically implicated. There are gaps in our understanding of how dopaminergic medications influence symptom awareness, and a need for longitudinal studies of how awareness changes over time in Parkinson's disease and Dementia with Lewy Bodies.

Plasma Phospho-Tau Identifies Alzheimer's Co-Pathology in Patients with Lewy Body Disease

BACKGROUND

Alzheimer's disease co-pathology is common in dementia with Lewy bodies and Parkinson's disease with dementia (Lewy body disease) and can reliably be detected with positron emission tomography (PET) or cerebrospinal fluid (CSF) biomarkers. Recently developed blood biomarkers are more accessible and less expensive alternatives.

OBJECTIVE

To investigate if plasma phospho-tau217 and phospho-tau181 can detect Alzheimer's pathology in Lewy body disease with dementia.

METHODS

In this cross-sectional study we investigated plasma phospho-tau217 and phospho-tau181 in 35 patients with Lewy body disease with dementia. Patients underwent tau-PET imaging (¹⁸ F-RO948).

RESULTS

Plasma phospho-tau217 correlated with plasma phospho-tau181, CSF phospho-tau217 (r_s = 0.68, P < 0.001), and negatively with CSF β-amyloid_42/40 (r_s = -0.52, P = 0.001). Plasma phospho-tau217 and phospho-tau181 correlated with tau-PET signal in the temporal cortex (r_s  > 0.56, P < 0.001) and predicted abnormal tau-PET status and β-amyloid status (area under the curve > 0.78 and > 0.81, respectively).

CONCLUSION

Plasma phospho-tau might be a useful marker for Alzheimer's co-pathology in Lewy body disease with dementia. © 2020 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Prevalence and clinical associations of tau in Lewy body dementias: A systematic review and meta-analysis

INTRODUCTION

Alzheimer's disease neuropathologies (amyloid-β and tau) frequently co-exist to varying degrees in Lewy body dementias (LBD), which include dementia with Lewy bodies (DLB) and Parkinson's disease dementia (PDD).

OBJECTIVES

To investigate the prevalence of tau in DLB and PDD, and its associations with clinical outcomes.

METHODS

We searched the major electronic databases using the search term: ("dementia with Lewy bodies" OR "diffuse Lewy body disease" OR "Lewy body variant of Alzheimer's disease") AND ("tau protein" OR "tauopathy" OR "neurofibrillary tangle"), for relevant studies which evaluated tau in LBD. Forty-nine articles met the inclusion criteria for data extraction. Where appropriate, a random-effect meta-analysis was performed to obtain pooled estimates for prevalence and risk ratios (RR) or standardized mean differences (SMD) for clinical features, diagnostic accuracy and cognition.

RESULTS

Braak neurofibrillary tangle stage ≥ III was observed in 66% (n = 1511, 95%CI 60%-73%) of DLB and 52% (n = 433, 95%CI 27%-76%) of PDD at autopsy. Abnormal CSF phosphorylated-tau levels were present in 28% (n = 925, 95%CI 25%-31%) of DLB and 15% (n = 172, 95%CI 5%-24%) of PDD cases. Higher tau burden in DLB was associated with reduced likelihood of manifesting visual hallucinations (RR 0.56; 95%CI 0.40-0.77) and motor parkinsonism (RR 0.62; 95%CI 0.40-0.98), lower diagnostic accuracy of DLB during life (RR 0.49; 95%CI 0.38-0.64) and worse cognition prior to death (SMD 0.63; 95%CI 0.46-0.81).

CONCLUSIONS

Tau is common in LBD and may reduce clinical diagnostic accuracy in people with DLB. Prospective longitudinal studies are needed to understand the roles of co-morbid neuropathologies in Lewy body dementias.

NREM sleep arousal-related disorders reflect cognitive impairment in Parkinson's disease

BACKGROUND

Sleep disorders and cognitive impairment are frequently reported in Parkinson's disease (PD) as non-motor disabling symptoms. While it is known that REM sleep Behaviour Disorder (RBD) in PD is associated with motor and cognitive decline, little is known about the neurobiological significance of NREM sleep arousal-related disorders.

OBJECTIVES

to evaluate the cognitive and clinical correlates of arousal-related disorders in PD.

METHODS

Clinical data and video-polysomnography were analysed from one hundred-seventy consecutive subjects with PD. Based on the neuropsychological assessment, the subjects were divided into three groups: no cognitive impairment (PD; n = 58), mild cognitive impairment (PD-MCI; n = 58) and overt dementia (PDD; n = 54).

RESULTS

Arousal-related disorders by history were reported in 32.9% of the subjects: 10.3% PD, 31.6% PD-MCI and 59.3% PDD (p = 0.001). Video-PSG captured arousal-related disorders in 1.7% PD, 21.2% MCI-PD and 35.6% PDD (p = 0.001). Arousal-related disorders and RBD were recorded in the same night in 7.7% PD, 9.8% MCI-PD and 15.6% PDD (p = 0.04). Patients with arousal-related disorders captured at V-PSG have a longer disease duration (p = 0.003), higher UPDRS score (p = 0.039), longer duration of treatment with levodopa (p = 0.017) and dopamine agonists (p = 0.018), worse H&Y staging (p = 0.001), lower MMSE score (p = 0.019) and more frequently hallucinations (p = 0.004). In multivariate analysis, cognitive impairment significantly increases the risk of arousal-related disorders (OR 3.387-95% CI 1.395-8.220, p = 0.007).

CONCLUSION

Arousal-related disorders appear to be a marker of cognitive decline in PD. Recognizing arousal-related disorders should make clinicians aware of a possible cognitive decline in PD and eventually modify the therapeutic approach.

A Comparative Study of the Behavioral Profile of the Behavioral Variant of Frontotemporal Dementia and Parkinson's Disease Dementia

BACKGROUND

Executive dysfunction is the common thread between pure cortical dementia like the behavioral variant of frontotemporal dementia (bvFTD) and subcortical dementia like Parkinson's disease dementia (PDD). Although there are clinical and cognitive features to differentiate cortical and subcortical dementia, the behavioral symptoms differentiating these 2 conditions are still not well known.

OBJECTIVE

To evaluate the behavioral profile of bvFTD and PDD and compare them to find out which behavioral symptoms can differentiate between the two.

METHODS

Twenty consecutive patients with bvFTD (>1 year after diagnosis) and 20 PDD patients were recruited according to standard diagnostic criteria. Behavioral symptoms were collected from the reliable caregiver by means of a set of questionnaires and then compared between the 2 groups.

RESULTS

bvFTD patients had more severe disease and more behavioral symptoms than PDD. bvFTD patients were different from PDD patients due to their significantly greater: loss of basic emotion (p < 0.001, odds ratio [OR] 44.33), loss of awareness of pain (p < 0.001, OR 44.33), disinhibition (p < 0.001, OR 35.29), utilization phenomenon (p = 0.008, OR 22.78), loss of taste discrimination (p < 0.001, OR 17), neglect of hygiene (p = 0.001, OR 13.22), loss of embarrassment (p = 0.003, OR 10.52), wandering (p = 0.004, OR 9.33), pacing (p = 0.014, OR 9), selfishness (p = 0.014, OR 9), increased smoking (p = 0.014, OR 9), increased alcohol consumption (p = 0.031, OR 7.36), social avoidance (p = 0.012, OR 6.93), mutism (p = 0.041, OR 5.67), and failure to recognize objects (p = 0.027, OR 4.33). The bvFTD patients were also significantly less suspicious (p = 0.001, OR 0.0295), less inclined to have a false belief that people were in their home (p = 0.014, OR 0.11) and had fewer visual illusions/hallucinations (p = 0.004, OR 0.107) than PDD patients.

CONCLUSION

Behavioral symptoms are helpful to distinguish bvFTD from PDD, and thus also cortical dementia with frontal-lobe dysfunction from subcortical dementia.

Altered awareness of motor symptoms in Parkinson's disease and Dementia with Lewy Bodies: A systematic review

OBJECTIVES

Altered awareness of motor symptoms is reported in people with Parkinson's disease and Dementia with Lewy Bodies, and may adversely affect quality of life and medication concordance. How symptom awareness is influenced by motor and cognitive disease severity, age and medication use is not fully understood. We carried out a systematic review of the literature on motor symptom awareness in Parkinson's disease and Dementia with Lewy Bodies.

METHODS

Pubmed and Wed of Science were searched for relevant articles published in or prior to March 2019. Data regarding participant demographics, diagnosis, cognitive status, method of assessing awareness and study findings were extracted from relevant publications.

RESULTS

Sixteen relevant publications were identified. Motor symptom awareness appears to decline over the course of Parkinson's disease. Imaging studies implicate the prefrontal cortex, with different mechanisms involved in hypokinesia and dyskinesia awareness. The hypothesis that people with right hemisphere based disease would have more severely reduced awareness is only weakly supported. Most studies focused on cognitively intact individuals, and on awareness of dyskinesia rather than hypokinesia.

CONCLUSIONS

Whilst reduced awareness of dyskinesia and to a lesser extent hypokinesia is common, there is a lack of longitudinal data on how awareness changes over time, and how it interacts with global cognitive changes. Motor symptom awareness in Dementia with Lewy Bodies is understudied. Future studies of symptom awareness should include robust assessment of overall cognitive functioning, and use a longitudinal design to elucidate how awareness changes over time. J Am Geriatr Soc 68:-, 2020.

Intranasal insulin ameliorates cognitive impairment in a rat model of Parkinson's disease through Akt/GSK3β signaling pathway

AIMS

Parkinson's disease dementia (PDD) is one of the most common non-motor symptoms of advanced Parkinson's disease (PD). This study aimed to determine whether intranasal insulin has protective effects on cognition in the rat PD model induced by 6-hydroxylase dopamine (6-OHDA) through the insulin signaling pathway.

MATERIALS AND METHODS

The rats were given intranasal insulin administration for six weeks after unilateral medial forebrain bundle (MFB) injection of 6-OHDA. Then a series of cognitive-behavioral tests, immunofluorescence, and immunoblotting was performed on the rats.

KEY FINDINGS

The results demonstrated that the injection of 6-OHDA in the unilateral MFB damaged working memory and long-term habituation of rats in the T-maze rewarded alternation test and hole-board test. Besides, rats with unilateral 6-OHDA injury performed poorly in terms of escape latency and average speed during the hidden platform training phase rather than in the probe trial of the Morris Water Maze (MWM) test. Immunofluorescence results showed that unilateral 6-OHDA injury in MFB led to the massive death of ipsilateral-substantia nigra (SN) tyrosine hydroxylase (TH)-positive neurons. Western blot results further indicated that 6-OHDA-induced necrosis of ipsilateral-SN dopaminergic neurons reduced the levels of p-Akt (Ser473) and p-GSK3β (Ser9) in the ipsilateral-hippocampus.

SIGNIFICANCE

These findings provide a solid evidence base for the relationship between PD cognitive impairment and insulin signaling pathways.

Fluctuating cognition in the Lewy body dementias

Fluctuating cognition is a core diagnostic feature of dementia with Lewy bodies and is also a key clinical feature of Parkinson's disease dementia. These dementias share common pathological features and are referred to as Lewy body dementias. Whilst highly prevalent in Lewy body dementia, with up to 90% of patients experiencing the symptom at some point in the disease trajectory, clinical identification of fluctuating cognition is often challenging. Furthermore, its underlying pathophysiological processes remain unclear. However, neuroimaging and neurophysiological techniques have recently provided insight into potential drivers of the phenomenon. In this update, we review data pertaining to clinical features and underlying mechanisms of fluctuating cognition in Lewy body dementia. We collate evidence for different proposed aetiologies: fluctuating cognition as an attentional disorder, as a consequence of loss of cholinergic drive, as a manifestation of failure in neuronal efficiency and synchrony, and as a disorder of sleep/arousal. We also review data relating to putative mechanisms that have received less attention to date. Increased understanding of fluctuating cognition may help to illuminate pathophysiological mechanisms in cognitive processing in Lewy body dementia, guide future research, and facilitate the design of targeted therapeutic approaches.

Clinical and Neuropathological Features Associated With Loss of RAB39B

BACKGROUND

Pathogenic variants in the small GTPase Ras Analogue in Brain 39b (RAB39B) have been linked to the development of early-onset parkinsonism. The study was aimed at delineating the clinical and neuropathological features associated with a previously reported pathogenic variant in RAB39B (c.503C>A p.T168K) and testing for dysregulation of RAB39B in idiopathic PD.

METHODS

Clinical details of a male individual hemizygous for the T168K variant were collected by systematic review of medical records. Neuropathological studies of fixed brain tissue were performed and steady-state RAB39B levels were determined by western blot analysis.

RESULTS

Neuropathological examination showed extensive dopaminergic neuron loss, widespread Lewy pathology, and iron accumulation in the substantia nigra. Additional pathology was observed in the hippocampus and thalamus. Western blot analysis demonstrated that the T168K variant results in loss of RAB39B. In individuals with idiopathic PD (n = 10, 6 male/4 female), steady-state RAB39B was significantly reduced in the prefrontal cortex and substantia nigra.

CONCLUSIONS

T168K RAB39B is unstable in vivo and associated with dopaminergic neuron loss and Lewy pathology. Dysregulation of RAB39B in the prefrontal cortex and substantia nigra of individuals with idiopathic PD potentially implicates the protein more broadly in the pathological mechanisms underlying PD and related Lewy body disorders. © 2020 International Parkinson and Movement Disorder Society.

Cognitive profiles and optimal cut-offs for routine cognitive tests in elderly individuals with Parkinson's disease, Parkinson's disease dementia, Alzheimer's disease, and normal cognition

AIM

The cognitive impairment seen in Parkinson's disease (PD) results in patient disability and reduced quality of life. However, using cognitive screening scales specific to PD in routine clinical practice is difficult because of limited time, resources, and skills. We studied the ability of routine cognitive tests to differentiate between Parkinson's disease dementia (PDD) and PD and among the neuropsychological profiles of elderly individuals with PD, PDD, Alzheimer's disease (AD), and normal cognition.

METHODS

This cross-sectional study involved 124 subjects. Subjects were 35 cognitively normal elderly and 37 elderly individuals with PD, 22 with PDD, and 30 with AD. All subjects were diagnosed by a specialist using standard criteria. Clinically relevant data and scores from the Montreal Cognitive Assessment and the Thai Mental State Examination were collected. Cognitive test scores were compared among groups. Receiver operating characteristic curves were constructed for a range of cut-off points to explore the sensitivity and specificity of the screening tools to detect PDD.

RESULTS

There were 74 female subjects (59.7%), and the average age of all subjects was 75.6 years. The median score on the modified Hoehn and Yahr scale was 2.5 in subjects with PD and 4 in those with PDD (P < 0.001). The cut-offs for differentiating PDD from PD were 25 on the Thai Mental State Examination and 14 on the Montreal Cognitive Assessment. The sensitivity of the Thai Mental State Examination was 78.4%, and the specificity was 66.7% (area under the curve: 0.828). The sensitivity of the Montreal Cognitive Assessment was 81.1%, and the specificity was 75% (area under the curve: 0.876). There was a significant difference in the memory and language subdomains between AD and PDD (P < 0.05).

CONCLUSIONS

The cut-offs used to differentiate PDD from PD were not the same as routine cut-offs in distinguishing AD from normal elderly. The cognitive profile deficit in PDD differed from that in AD. Interpretations of positive screenings test should take this finding into consideration.

Patterns of olfactory functional networks in Parkinson's disease dementia and Alzheimer's dementia

Hyposmia is common in Alzheimer's dementia (AD) and Parkinson's disease dementia (PDD). We evaluated the pattern of olfactory functional connectivity (FC) in AD and PDD to uncover neural correlates that are related to olfactory dysfunction. This study enrolled 57 patients with AD and PDD and 25 control subjects. Using a seed-based approach, we compared the resting-state network from the seed-region-of-interest in the olfactory bulb, olfactory tract, piriform cortex, and orbitofrontal cortex (OFC) between groups. The PDD group showed lower FC with striatal-thalamic-frontal regions from the olfactory bulb than the AD group. The PDD group showed lower FC from left OFC with striatal-frontal regions and lower FC from right OFC with left fronto-temporal areas than the AD group. In a correlation analysis, the FC from left OFC with right insula that differed between the PDD and control groups was positively correlated with olfactory function. The present study demonstrated that this distinct olfactory functional network pattern may represent different neural mechanisms for olfactory dysfunction in AD and PDD.

Behavioral defects associated with amygdala and cortical dysfunction in mice with seeded α-synuclein inclusions

Parkinson’s disease (PD) is defined by motor symptoms such as tremor at rest, bradykinesia, postural instability, and stiffness. In addition to the classical motor defects that define PD, up to 80% of patients experience cognitive changes and psychiatric disturbances, referred to as PD dementia (PDD). Pathologically, PD is characterized by loss of dopaminergic neurons in the substantia nigra pars compacta (SNpc) and intracellular inclusions, called Lewy bodies and Lewy neurites, composed mostly of α-synuclein. Much of PD research has focused on the role of α-synuclein aggregates in degeneration of SNpc dopamine neurons because of the impact of loss of striatal dopamine on the classical motor phenotypes. However, abundant Lewy pathology is also found in other brain regions including the cortex and limbic brain regions such as the amygdala, which may contribute to non-motor phenotypes. Little is known about the consequences of α-synuclein inclusions in these brain regions, or in neuronal subtypes other than dopamine neurons. This project expands knowledge on how α-synuclein inclusions disrupt behavior, specifically non-motor symptoms of synucleinopathies. We show that bilateral injections of fibrils into the striatum results in robust bilateral α-synuclein inclusion formation in the cortex and amygdala. Inclusions in the amygdala and prefrontal cortex primarily localize to excitatory neurons, but unbiased stereology shows no significant loss of neurons in the amygdala or cortex. Fibril injected mice show defects in a social dominance behavioral task and fear conditioning, tasks that are associated with prefrontal cortex and amygdala function. Together, these observations suggest that seeded α-synuclein inclusion formation impairs behaviors associated with cortical and amygdala function, without causing cell loss, in brain areas that may play important roles in the complex cognitive features of PDD

Alzheimer's disease pathology explains association between dementia with Lewy bodies and APOE-ε4/TOMM40 long poly-T repeat allele variants

Introduction

The role of TOMM40-APOE 19q13.3 region variants is well documented in Alzheimer's disease (AD) but remains contentious in dementia with Lewy bodies (DLB) and Parkinson's disease dementia (PDD).

Methods

We dissected genetic profiles within the TOMM40-APOE region in 451 individuals from four European brain banks, including DLB and PDD cases with/without neuropathological evidence of AD-related pathology and healthy controls.

Results

TOMM40-L/APOE-ε4 alleles were associated with DLB (OR_TOMM40-L = 3.61; P value = 3.23 × 10⁻⁹; OR_APOE-ε4 = 3.75; P value = 4.90 × 10⁻¹⁰) and earlier age at onset of DLB (HR_TOMM40-L = 1.33, P value = .031; HR_APOE-ε4 = 1.46, P value = .004), but not with PDD. The TOMM40-L/APOE-ε4 effect was most pronounced in DLB individuals with concomitant AD pathology (OR_TOMM40-L = 4.40, P value = 1.15 × 10⁻⁶; OR_APOE-ε4 = 5.65, P value = 2.97 × 10⁻⁸) but was not significant in DLB without AD. Meta-analyses combining all APOE-ε4 data in DLB confirmed our findings (OR_DLB = 2.93, P value = 3.78 × 10⁻⁹⁹; OR_DLB+AD = 5.36, P value = 1.56 × 10⁻⁴⁷).

Discussion

APOE-ε4/TOMM40-L alleles increase susceptibility and risk of earlier DLB onset, an effect explained by concomitant AD-related pathology. These findings have important implications in future drug discovery and development efforts in DLB.

LRP10 variants in Parkinson's disease and dementia with Lewy bodies in the South-West of the Netherlands

OBJECTIVE

To analyse LRP10 variants, recently associated with the development of Parkinson's disease (PD), Parkinson's disease dementia (PDD) and dementia with Lewy bodies (DLB), in a series of patients and controls from the South-West of the Netherlands (Walcheren).

METHODS

A series of 130 patients with PD, PDD or DLB were clinically examined, and a structured questionnaire used to collect information about family history of PD and dementia. The entire LRP10 coding region was sequenced by Sanger methods in all patients, and haplotype analysis was performed for one recurrent LRP10 variant. The fragments containing possibly pathogenic LRP10 variants were sequenced in 62 unaffected control subjects from the same region. Other known PD-associated genes were analyzed by exome sequencing and gene dosage in the carriers of LRP10 variants.

RESULTS

Four patients were carriers of a rare heterozygous, possibly pathogenic LRP10 variant: p.Arg151Cys, p.Arg263His, and p.Tyr307Asn. None of these variants was detected among the controls, nor were additional mutations identified in known PD-associated genes in the four LRP10 variant carriers. The previously reported p.Tyr307Asn variant was identified in two patients (with PD and PDD), who are connected genealogically within six generations, and in one of their relatives with cognitive decline. Haplotype analysis suggests a common founder for the p.Tyr307Asn variant carriers analyzed.

DISCUSSION

We report three possibly pathogenic LRP10 variants in patients with PD and PDD from a local Dutch population. The identification of additional patients carrying the p.Tyr307Asn variant provides some further evidence that this variant is pathogenic for PD and PDD.

Frontal atrophy as a marker for dementia conversion in Parkinson's disease with mild cognitive impairment

This study aimed to investigate the cortical neural correlates of dementia conversion in Parkinson's disease with mild cognitive impairment (PD-MCI). We classified 112 patients with drug-naïve early stage PD meeting criteria for PD-MCI into either PD with dementia (PDD) converters (n = 34) or nonconverters (n = 78), depending on whether they developed dementia within 4 years of PD diagnosis. Cortical thickness analyses were performed in 34 PDD converters and 34 matched nonconverters. Additionally, a linear discriminant analysis was performed to distinguish PDD converters from nonconverters using cortical thickness of the regions that differed between the two groups. The PDD converters had higher frequencies of multiple domain MCI and amnestic MCI with storage failure, and poorer cognitive performances on frontal/executive, memory, and language function domains than did the nonconverters. Cortical thinning extending from the posterior cortical area into the frontal region was observed in PDD converters relative to nonconverters. The discriminant analysis showed that the prediction model with two cortical thickness variables in the right medial superior frontal and left olfactory cortices optimally distinguished PDD converters from nonconverters. Our data suggest that cortical thinning in the frontal areas including the olfactory cortex is a marker for early dementia conversion in PD-MCI.

Clinical and neuropathological differences between Parkinson's disease, Parkinson's disease dementia and dementia with Lewy bodies - current issues and future directions

Lewy body diseases share clinical, pathological, genetic and biochemical signatures, and are regarded as a highly heterogeneous group of neurodegenerative disorders. Inclusive of Parkinson's disease (PD), Parkinson's disease dementia (PDD) and dementia with Lewy bodies (DLB), controversy still exists as to whether they should be considered as separate disease entities or as part of the same disease continuum. Here we discuss emerging knowledge relating to both clinical, and neuropathological differences and consider current biomarker strategies as we try to improve our diagnostic capabilities and design of disease modifying therapeutics for this group of debilitating neurodegenerative disorders. This article is part of the Special Issue "Synuclein".

Mild cognitive impairment reverters have a favorable cognitive prognosis and cortical integrity in Parkinson's disease

This study aimed to investigate whether reversion to cognitively normal status (CogN) is related to a favorable cognitive prognosis in Parkinson's disease with mild cognitive impairment (PD-MCI). We recruited 217 patients with PD-MCI who underwent serial neuropsychological assessments 3-5 times (mean interval, 1.84 years). Thirty-six patients reverted to CogN (reverters) during follow-up, whereas the other 181 did not (nonreverters). We assessed the risk of cognitive worsening in PD-MCI reverters, nonreverters, and patients with PD-CogN (n = 88). In addition, we performed comparative analyses of comprehensive neuroimaging studies between the PD-MCI reverter (n = 17) and nonreverter (n = 34) subgroups. PD-MCI reverters had a lower risk of dementia conversion than nonreverters. In addition, PD-MCI reverters had similar risks of cognitive worsening with patients with PD-CogN. PD-MCI reverters exhibited greater cortical thickness in the right parahippocampal gyrus and less severely decreased functional connectivity in the default mode and executive control networks relative to nonreverters. Our results suggest that PD-MCI reverters have relatively preserved structural and functional integrity and a favorable cognitive prognosis compared with nonreverters.

Diffuse Lewy body disease

Diffuse Lewy body disease, also called dementia with Lewy bodies (DLB), is defined as progressive dementia and pathological Lewy bodies distributed in the central and autonomic nervous systems. The clinical features are dementia, cognitive fluctuations, visual hallucinations, parkinsonism, and REM sleep behavior disorder (RBD). Confirmatory techniques include dopamine transporter imaging, meta-iodobenzylguanidine (MIBG) myocardial scintigraphy, and polysomnography. The pathology finding in DLB is misfolded alpha-synuclein, the main component of Lewy bodies, propagating in the central nervous system. This may interrupt the acetylcholine pathway and activate an inflammatory response. Mutations of several genes have been found in patients with DLB, including SNCA, GBA, and APOE. The differential diagnosis of DLB and Parkinson's disease with dementia (PDD) is a debated issue. Clinical features distinguishing DLB from PDD include the timing of dementia and visual hallucinations, responses to dopaminergic agents and anti-psychotics, and imaging findings. As to the management of DLB, cholinesterase inhibitors are the Level-A recommendation for treating dementia in DLB patients and also are beneficial for treating visual hallucinations and psychotic symptoms. Dopamine agonists have the risk of inducing psychotic symptoms, while levodopa should be used carefully for motor symptoms. Melatonin and clonazepam are effective in controlling RBD. Several other treatment methods are undergoing trials, including pimavanserine, nilotinib, psychological interventions, and behavior therapy.

Behavioral symptomatology and psychopharmacology of Lewy body dementia

Lewy body dementia (LBD) is an umbrella term for major neurocognitive disorders caused by Lewy body pathology. Parkinson's disease dementia (PDD) and Dementia with Lewy bodies (DLB) are the two main syndromes in LBD. LBDs typically present with cognitive impairment, cholinergic deficiency, neuropsychiatric symptoms such as visual hallucinations and paranoid delusions, as well as parkinsonian symptoms. Due to the urgency in diagnosing LBD early in the disease course to provide the most optimal management of these syndromes, it is important that clinicians elicit the most clinically significant symptoms during patient encounters. The focus of this chapter is to discuss current LBD classification systems and assessments, neuropathology of LBDs, behavioral symptomatology, contemporary management options, and possible future targets of treatment. PubMed was searched to obtain reviews and studies that pertain to classification, behavioral symptomatology, neurobiology, neuroimaging, and treatment of LBDs. Articles were chosen with a predilection to more recent clinical trials and systematic reviews or meta-analyses. Updates to diagnostic criteria have increased clinical diagnostic sensitivity and specificity. Current therapeutic modalities are limited as there is no current disease-modifying drug available. Cholinesterase inhibitors have been reported to be effective in decreasing neuropsychiatric and cognitive symptoms. Neuroleptics should be avoided unless clinically indicated. There is a paucity of studies investigating treatment options for mood symptoms. Current novel targets of treatment focus on decreasing α-synuclein burden. LBDs are a group of dementia syndromes that affect a significant portion of the elderly population. Early diagnosis and treatment is necessary to improve patient quality of life with current treatment options more focused on alleviating severe symptomatology rather than modifying disease pathology.

The Influence of Body Mass Index at Diagnosis on Cognitive Decline in Parkinson's Disease

BACKGROUND AND PURPOSE

Associations between alterations in body mass index (BMI) and cognitive function have been reported in Parkinson's disease (PD). We investigated whether the BMI at a PD diagnosis is associated with cognitive decline and the future development of dementia.

METHODS

We recruited 70 patients with de novo PD who underwent neuropsychological testing every 3 years and were followed up for more than 6 years. We classified patients into the following three groups based on their BMI at the diagnosis: under-/normal weight (n=21), overweight (n=22), and obese (n=27). We evaluated differences in the rate of cognitive decline over time among the groups using linear mixed models and the conversion rate to dementia using survival analysis.

RESULTS

The obese patients with PD showed a slower deterioration of global cognitive function as well as language and memory functions than did the under-/normal-weight group during the 6-year follow-up. The three BMI groups showed different rates of conversion to dementia (log-rank test: p=0.026). The combined overweight and obese group showed a lower risk of developing dementia compared with the under-/normal-weight group (hazard ratio= 0.36, 95% CI=0.12-0.82, p=0.046).

CONCLUSIONS

We have demonstrated that a higher-than-normal BMI at the time of a PD diagnosis has a protective effect against the deterioration of cognitive function and the conversion to dementia.

Molecular Imaging of Dementia With Lewy Bodies

Dementia with Lewy bodies (DLB) is the second most common cause of neurodegenerative dementia. The core clinical features of DLB include fluctuating cognition, visual hallucinations, rapid eye movement sleep behavior disorder, and parkinsonism. Molecular imaging is a powerful tool to assess the brain function in vivo. In this chapter, we reviewed the positron emission tomography, single-photon emission computed tomography, and [¹²³I]-metaiodobenzylguanidine scintigraphy studies evaluating the pathological processes underlying DLB, including altered brain metabolism and neurotransmitter pathways, abnormal protein aggregation, and neuroinflammation. These techniques can aid in the differential diagnosis of DLB (versus Alzheimer's disease and related dementia) and in the monitoring disease progression and treatment efficacy of disease-modifying drugs. Furthermore, we explored the limitations of current imaging biomarkers and future directions, particularly focusing on the vital need for tracers that have high affinity for alpha-synuclein.

Association between olfactory loss and cognitive deficits in Parkinson's disease

OBJECTIVE

The aim of this study was to compare the cognitive deficits and olfaction in PD patients.

PATIENTS AND METHODS

In all, 42 PD patients and 38 controls were selected. All the individuals in both groups underwent cognitive assessment with the SCOPA-Cog neuropsychological battery and Mini-Mental State Examination (MMSE) and olfactory assessment with the Sniffin' Sticks Screening 12 Test. Parkinson's disease dementia (PDD) was diagnosed using the International Parkinson and Movement Disorder Society (MDS) criteria.

RESULTS

The prevalence of olfactory dysfunction in PD patients was 95.24% (40/42). There was no statistically significant difference in olfaction when compared to patients with PDD and PD without cognitive deficits (5.12 ± 3.25 vs. 6.71 ± 2.63, p = 0.115). Attention [r = 0.35, 95% CI = (0.05-0.59), p =  0.01] was the only cognitive domain correlated with olfactory loss in PD patients. There was a higher correlation among the scores of cognitive and olfactory assessments in controls, r=0.40 (95% CI = [0.09-0.64], p = 0.007), with MMSE.

CONCLUSION

The olfactory deficits prevalence in PD patients was significantly high. There may be a correlation between frontal lobe dysfunction and olfactory deficit.

Non-pharmacological interventions for Lewy body dementia: a systematic review

Lewy body dementia (consisting of dementia with Lewy bodies and Parkinson's disease dementia) is a common neurodegenerative disease characterised by visual hallucinations, fluctuating attention, motor disturbances, falls, and sensitivity to antipsychotics. This combination of features presents challenges for pharmacological management. Given this, we sought to review evidence for non-pharmacological interventions with patients with Lewy body dementia and their carers. Bibliographic databases were searched using a wide range of search terms and no restrictions were placed on study design, language, or clinical setting. Two reviewers independently assessed papers for inclusion, rated study quality, and extracted data. The search identified 21 studies including two randomised controlled trials with available subgroup data, seven case series, and 12 case studies. Most studies reported beneficial effects of the interventions used, though the only sizeable study was on dysphagia, showing a benefit of honey-thickened liquids. Given the heterogeneity of interventions and poor quality of the studies overall, no quantitative synthesis was possible. Overall, identified studies suggested possible benefits of non-pharmacological interventions in Lewy body dementia, but the small sample sizes and low quality of studies mean no definite recommendations can be offered. Our findings underscore the clear and urgent need for future research on this topic.

Deep Brain Stimulation: A Potential Treatment for Dementia in Alzheimer's Disease (AD) and Parkinson's Disease Dementia (PDD)

Damage to memory circuits may lead to dementia symptoms in Alzheimer's disease (AD) and Parkinson's disease dementia (PDD). Recently, deep brain stimulation (DBS) has been shown to be a novel means of memory neuromodulation when critical nodes in the memory circuit are targeted, such as the nucleus basalis of Meynert (NBM) and fornix. Potential memory improvements have been observed after DBS in patients with AD and PDD. DBS for the treatment of AD and PDD may be feasible and safe, but it is still preliminary. In this review, we explore the potential role of DBS for the treatment of dementia symptoms in AD and PDD. Firstly, we discuss memory circuits linked to AD and PDD. Secondly, we summarize clinical trials and case reports on NBM or fornix stimulation in AD or PDD patients and discuss the outcomes and limitations of these studies. Finally, we discuss the challenges and future of DBS for the treatment of AD and PDD. We include the latest research results from Gratwicke et al. (2017) and compare them with the results of previous relevant studies, and this would be a worthy update of the literature on DBS for dementia. In addition, we hypothesize that the differences between AD and PDD may ultimately lead to different results following DBS treatment.

Quantitative electroencephalography as a marker of cognitive fluctuations in dementia with Lewy bodies and an aid to differential diagnosis

•

EEG slowing was evident in dementia with Lewy bodies (DLB) and Parkinson’s disease dementia (PDD) and less in Alzheimer’s disease (AD) patients compared to controls.

•

Dominant rhythm variability was larger in AD but only correlated with cognitive fluctuations in DLB.

•

QEEG variables classified DLB and AD patients with high sensitivity and specificity.

Objective

We investigated for quantitative EEG (QEEG) differences between Alzheimer’s disease (AD), dementia with Lewy bodies (DLB) and Parkinson’s disease dementia (PDD) patients and healthy controls, and for QEEG signatures of cognitive fluctuations (CFs) in DLB.

Methods

We analysed eyes-closed, resting state EEGs from 18 AD, 17 DLB and 17 PDD patients with mild dementia, and 21 age-matched controls. Measures included spectral power, dominant frequency (DF), frequency prevalence (FP), and temporal DF variability (DFV), within defined EEG frequency bands and cortical regions.

Results

DLB and PDD patients showed a leftward shift in the power spectrum and DF. AD patients showed greater DFV compared to the other groups. In DLB patients only, greater DFV and EEG slowing were correlated with CFs, measured by the clinician assessment of fluctuations (CAF) scale. The diagnostic accuracy of the QEEG measures was 94% (90.4–97.9%), with 92.26% (80.4–100%) sensitivity and 83.3% (73.6–93%) specificity.

Conclusion

Although greater DFV was only shown in the AD group, within the DLB group a positive DFV – CF correlation was found. QEEG measures could classify DLB and AD patients with high sensitivity and specificity.

Significance

The findings add to an expanding literature suggesting that EEG is a viable diagnostic and symptom biomarker in dementia, particularly DLB.

Oscillatory activity and cortical coherence of the nucleus basalis of Meynert in Parkinson's disease dementia

BACKGROUND

Deep brain stimulation (DBS) of the nucleus basalis of Meynert (NBM) is a new potential treatment for Parkinson's Disease dementia (PDD) and other types of dementia. To get a better understanding of this structure, its local neurophysiological properties and cortical connectivity patterns were studied.

METHODS

We simultaneously recorded DBS local field potentials (LFPs) and electroencephalography (EEG) in two patients with PDD. Both patients had DBS electrodes in the internal globus pallidus (GPi) with one or more distal contacts close to or inside the NBM. Measurements were obtained during routine battery replacement. The distance of DBS contacts to the NBM were calculated using CT-MRI fusion.

RESULTS

Delta (1-4 Hz) oscillations were more prominently present in the NBM region than in its vicinity, whereas temporal coherence in the theta (4-8 Hz) range was less outspoken.

CONCLUSION

These neurophysiological characteristics, if also proven in larger cohorts, might help to map the NBM more precisely during electrode implantation.

Apolipoprotein E genotypes and longevity across dementia disorders

INTRODUCTION

The ε4 allele of the apolipoprotein E (APOE) gene is a prominent risk factor for Alzheimer's disease (AD), but its implication in other dementias is less well studied.

METHODS

We used a data set on 2858 subjects (1098 AD, 260 vascular dementia [VaD], 145 mixed AD and VaD, 90 other dementia diagnoses, and 1265 controls) to examine the association of APOE polymorphisms with clinical dementia diagnoses, biomarker profiles, and longevity.

RESULTS

The ε4 allele was associated with reduced longevity as ε4 versus ε3 homozygotes lived on average 2.6 years shorter (P = .006). In AD, ε4 carriers lived 1.0 years shorter than noncarriers (P = .028). The ε4 allele was more prevalent in AD, mixed AD and VaD, and VaD patients compared to controls, but not in other dementia disorders.

DISCUSSION

The APOE ε4 allele is influential in AD but might also be of importance in VaD and in mixed AD and VaD, diseases in which concomitant AD pathology is common.

Systematic review of the efficacy of non-pharmacological interventions in people with Lewy body dementia

ABSTRACTBackground:Pharmacological interventions for Lewy body dementia (LBD), especially for its non-cognitive symptoms, are limited in their efficacy and tolerability. Clinicians are often uncertain about non-pharmacological interventions and their efficacy in managing cognitive and non-cognitive symptoms of LBD. Therefore, we aimed to systematically review the existing literature on non-pharmacological interventions for people with LBD.

METHODS

We carried out a systematic search using six databases. All human studies examining impact of any non-pharmacological intervention on LBD were assessed for cognitive, physical, psychiatric, and quality-of-life outcomes. Study quality was assessed by Effective Public Health Practice Project Quality Assessment Tool for Quantitative Studies and the CARE criteria checklist.

RESULTS

Prevailing evidence supporting the efficacy of non-pharmacological interventions is weak. We screened 1,647 papers. Fifteen studies (n = 61) including 11 case reports were found eligible for this systematic review. Interventions and reported outcomes were heterogeneous. Deep brain stimulation of the nucleus basalis of Meynert reportedly conferred cognitive benefit. Electroconvulsive therapy and repetitive transcranial magnetic stimulation have been reported to ameliorate depressive symptoms. Transcranial direct current stimulation was observed to improve attention. Exercise-based interventions reportedly improve various clinically important outcomes. Spaced retrieval memory training and environmental intervention for "mirror sign" have also been reported.

CONCLUSIONS

Several non-pharmacological interventions have been studied in LBD. Although evidence supporting their efficacy is not robust, prevailing preliminary evidence and limitations of available pharmacological interventions indicate the need to consider appropriate non-pharmacological interventions, while planning comprehensive care of LBD patients. Larger trials evaluating the efficacy of non-pharmacological interventions for LBD are needed.