Quantifying fluctuation in dementia with Lewy bodies, Alzheimer's disease, and vascular dementia

Design and Feasibility Analysis of a Smartphone-Based Digital Cognitive Assessment Study in the Framingham Heart Study

BACKGROUND

Smartphone-based digital technology is increasingly being recognized as a cost-effective, scalable, and noninvasive method of collecting longitudinal cognitive and behavioral data. Accordingly, a state-of-the-art 3-year longitudinal project focused on collecting multimodal digital data for early detection of cognitive impairment was developed.

METHODS AND RESULTS

A smartphone application collected 2 modalities of cognitive data, digital voice and screen-based behaviors, from the FHS (Framingham Heart Study) multigenerational Generation 2 (Gen 2) and Generation 3 (Gen 3) cohorts. To understand the feasibility of conducting a smartphone-based study, participants completed a series of questions about their smartphone and app use, as well as sensory and environmental factors that they encountered while completing the tasks on the app. Baseline data collected to date were from 537 participants (mean age=66.6 years, SD=7.0; 58.47% female). Across the younger participants from the Gen 3 cohort (n=455; mean age=60.8 years, SD=8.2; 59.12% female) and older participants from the Gen 2 cohort (n=82; mean age=74.2 years, SD=5.8; 54.88% female), an average of 76% participants agreed or strongly agreed that they felt confident about using the app, 77% on average agreed or strongly agreed that they were able to use the app on their own, and 81% on average rated the app as easy to use.

CONCLUSIONS

Based on participant ratings, the study findings are promising. At baseline, the majority of participants are able to complete the app-related tasks, follow the instructions, and encounter minimal barriers to completing the tasks independently. These data provide evidence that designing and collecting smartphone application data in an unsupervised, remote, and naturalistic setting in a large, community-based population is feasible.

Ecological validity of cognitive fluctuations in dementia with Lewy bodies

OBJECTIVES

Cognitive fluctuations are a core clinical feature of dementia with Lewy bodies (DLB), but their contribution to the everyday functioning difficulties evident DLB are not well understood. The current study evaluated whether intraindividual variability across a battery of neurocognitive tests (intraindividual variability-dispersion) and daily cognitive fluctuations as measured by informant report are associated with worse daily functioning in DLB.

METHODS

The study sample included 97 participants with consensus-defined DLB from the National Alzheimer's Coordinating Center (NACC). Intraindividual variability-dispersion was measured using the coefficient of variation, which divides the standard deviation of an individual's performance scores across 12 normed neurocognitive indices from the NACC neuropsychological battery by that individual's performance mean. Informants reported on daily cognitive fluctuations using the Mayo Fluctuations Scale (MFS) and on daily functioning using the functional activities questionnaire (FAQ).

RESULTS

Logistic regression identified a large univariate association of intraindividual variability-dispersion and presence of daily cognitive fluctuations on the MFS (Odds Ratio = 73.27, 95% Confidence Interval = 1.38, 3,895.05). Multiple linear regression demonstrated that higher intraindividual variability-dispersion and presence of daily cognitive fluctuations as assessed by the MFS were significantly and independently related to worse daily functioning (FAQ scores).

CONCLUSIONS

Among those with DLB, informant-rated daily cognitive fluctuations and cognitive fluctuations measured in the clinic (as indexed by intraindividual variability-dispersion across a battery of tests) were independently associated with poorer everyday functioning. These data demonstrate ecological validity in measures of cognitive fluctuations in DLB.

The central role of the Thalamus in psychosis, lessons from neurodegenerative diseases and psychedelics

The PD-DLB psychosis complex found in Parkinson's disease (PD) and Dementia with Lewy Bodies (DLB) includes hallucinations, Somatic Symptom/Functional Disorders, and delusions. These disorders exhibit similar presentation patterns and progression. Mechanisms at the root of these symptoms also share similarities with processes promoting altered states of consciousness found in Rapid Eye Movement sleep, psychiatric disorders, or the intake of psychedelic compounds. We propose that these mechanisms find a crucial driver and trigger in the dysregulated activity of high-order thalamic nuclei set in motion by ThalamoCortical Dysrhythmia (TCD). TCD generates the loss of finely tuned cortico-cortical modulations promoted by the thalamus and unleashes the aberrant activity of the Default Mode Network (DMN). TCD moves in parallel with altered thalamic filtering of external and internal information. The process produces an input overload to the cortex, thereby exacerbating DMN decoupling from task-positive networks. These phenomena alter the brain metastability, creating dreamlike, dissociative, or altered states of consciousness. In support of this hypothesis, mind-altering psychedelic drugs also modulate thalamic-cortical pathways. Understanding the pathophysiological background of these conditions provides a conceptual bridge between neurology and psychiatry, thereby helping to generate a promising and converging area of investigation and therapeutic efforts.

Diagnosis of vascular parkinsonism: A new tool for gait hypokinesia occurring in older persons

INTRODUCTION

Reliable diagnosis of vascular parkinsonism (VaP) in the presence of a gait hypokinesia is an issue that is encountered in geriatrics. The EVAMAR-AGEX study was focusing on the phenomenon of recurrent falls in older persons (OP) with this parkinsonian gait. The present study is focusing on the diagnosis of VaP-related parkinsonian gait by developing a diagnostic guidance model adapted to OP.

METHODS

Data from baseline and the 2-year follow-up visit were used to carry out univariate analysis and calculation of odds ratios, allowing to identify relevant variables to include in the diagnostic guidance model. To evaluate the model, confusion matrices were created, evaluating true positive, false negative, false positive and true negative incidences, sensitivity and specificity, and negative and positive predictive values.

RESULTS

79 patients included 58% male; average age 81.24 years. VaP diagnosis according to Zijlmans criteria occurred in 28%; neurodegenerative parkinsonian syndromes in 72%. A 4-criteria model was established to facilitate diagnostic: lack of prior hallucinations, lack of movement disorders tremor excluded, no cognitive fluctuations, and ≥75 years of age at diagnosis. In combination of 4/4 criteria, all of them were required to disclose a specificity of 91% in the diagnosis of VaP. In combination of 3/4, in case of negative test, a negative predictive value for VaP diagnosis of 0.97 was obtained.

CONCLUSION

The challenge of our tool is both to be able to rule out what is probably not a VaP and to argue what makes a VaP diagnosis probable in OP.

"It's You": Caregiver and Clinician Perspectives on Lucidity in People Living With Dementia

BACKGROUND AND OBJECTIVES

Episodes of lucidity (ELs), or a transient return of abilities believed to be lost in people living with dementia, are a growing area of interest. These events hold important implications for care, caregiving, and our understanding of underlying etiologies. Research on ELs is largely limited to retrospective reports. The perspectives of professional and family caregivers on ELs and research approaches can inform efforts to define and study lucidity. The present study examined family caregiver and hospice clinician experiences with and perspectives on ELs in people living with dementia and observational approaches to studying these events.

RESEARCH DESIGN AND METHODS

This exploratory, descriptive qualitative study employed semistructured interviews (N = 20 caregivers, N = 6 clinicians). Data were analyzed using Rapid Identification of Themes and subsequent duplicate review of interview data to enhance trustworthiness.

RESULTS

Most participants readily recalled events they perceived as ELs, describing a transient return of abilities they felt was significant and/or meaningful. Defining features, interpretations, and the perceived impact of ELs varied, although ELs were commonly conceptualized as a manifestation of self. Caregivers described extensive efforts to detect patterns and supportive social conditions for ELs. Participants supported use of audiovisual observation to study ELs and provided recommendations for privacy, workflow, and caregiver engagement.

DISCUSSION AND IMPLICATIONS

Interpretations of ELs are heterogeneous, and recognition of these events may necessitate close familiarity with the person living with dementia. Participants endorse observational approaches and integration of caregivers in this research.

Different peripheral expression patterns of the nicotinic acetylcholine receptor in dementia with Lewy bodies and Alzheimer's disease

BACKGROUND

The diffuse distribution of nicotinic cholinergic receptors (nAChRs) in both brain and peripheral immune cells points out their involvement in several pathological conditions. Indeed, the deregulated function of the nAChR was previously correlated with cognitive decline and neuropsychiatric symptoms in Alzheimer's disease (AD) and Dementia with Lewy bodies (DLB). The evaluation in peripheral immune cells of nAChR subtypes, which could reflect their expression in brain regions, is a prominent investigation area.

OBJECTIVES

This study aims to evaluate the expression levels of both the nAChR subunits and the main known inflammatory cytokines in peripheral blood mononuclear cells (PBMCs) of patients with DLB and AD to better characterize their involvement in these two diseases.

RESULTS

Higher gene expression levels of TNFα, IL6 and IL1β were observed in DLB and AD patients in comparison with healthy controls (HC). In our cohort, a reduction of nAChRα4, nAChRβ2 and nAChRβ4 was detected in both DLB and AD with respect to HC. Considering nAChR gene expressions in DLB and AD, significant differences were observed for nAChRα3, nAChRα4, nAChRβ2 and nAChRβ4 between the two groups. Moreover, the acetylcholine esterase (AChE) gene expression was significantly higher in DLB than in AD. Correlation analysis points out the relation between different nAChR subtype expressions in DLB (nAChRβ2 vs nAChRα3; nAChRα4 vs nAChRα3) and AD (nAChRα4 vs nAChRα3; nAChRα4 vs nAChRβ4; nAChRα7 vs nAChRα3; nAChRα7 vs nAChRα4).

CONCLUSIONS

Different gene expressions of both pro-inflammatory cytokines and nAChR subtypes may represent a peripheral link between inflammation and neurodegeneration. Inflammatory cytokines and different nAChRs should be valid and accurate peripheral markers for the clinical diagnosis of DLB and AD. However, although nAChRs show a great biological role in the regulation of inflammation, no significant correlation was detected between nAChR subtypes and the examined cytokines in our cohort of patients.

Quantitative EEG for early differential diagnosis of dementia with Lewy bodies

Introduction

Differentiating between the two most common forms of dementia, Alzheimer's dementia and dementia with Lewy bodies (DLB) remains difficult and requires the use of invasive, expensive, and resource-intensive techniques. We aimed to investigate the sensitivity and specificity of electroencephalography quantified using the statistical pattern recognition method (qEEG-SPR) for identifying dementia and DLB.

Methods

Thirty-two outpatients and 16 controls underwent clinical assessment (by two blinded neurologists), EEG recording, and a 6-month follow-up clinical assessment. EEG data were processed using a qEEG-SPR protocol to derive a Dementia Index (positive or negative) and DLB index (positive or negative) for each participant which was compared against the diagnosis given at clinical assessment. Confusion matrices were used to calculate sensitivity, specificity, and predictive values for identifying dementia and DLB specifically.

Results

Clinical assessment identified 30 cases of dementia, 2 of which were diagnosed clinically with possible DLB, 14 with probable DLB and DLB was excluded in 14 patients. qEEG-SPR confirmed the dementia diagnosis in 26 out of the 32 patients and led to 6.3% of false positives (FP) and 9.4% of false negatives (FN). qEEG-SPR was used to provide a DLB diagnosis among patients who received a positive or inconclusive result of Dementia index and led to 13.6% of FP and 13.6% of FN. Confusion matrices indicated a sensitivity of 80%, a specificity of 89%, a positive predictive value of 92%, a negative predictive value of 72%, and an accuracy of 83% to diagnose dementia. The DLB index showed a sensitivity of 60%, a specificity of 90%, a positive predictive value of 75%, a negative predictive value of 81%, and an accuracy of 75%. Neuropsychological scores did not differ significantly between DLB and non- DLB patients. Head trauma or story of stroke were identified as possible causes of FP results for DLB diagnosis.

Conclusion

qEEG-SPR is a sensitive and specific tool for diagnosing dementia and differentiating DLB from other forms of dementia in the initial state. This non-invasive, low-cost, and environmentally friendly method is a promising diagnostic tool for dementia diagnosis which could be implemented in local care settings.

Dispersion-based cognitive intra-individual variability in dementia with Lewy bodies

OBJECTIVE

Cognitive fluctuations are characteristic of dementia with Lewy bodies (DLB) but challenging to measure. Dispersion-based intra-individual variability (IIV-d) captures neurocognitive performance fluctuations across a test battery and may be sensitive to cognitive fluctuations but has not been studied in DLB.

METHOD

We report on 5,976 participants that completed the uniform data set 3.0 neuropsychological battery (UDS3NB). IIV-d was calculated via the intra-individual standard deviation across 12 primary UDS3NB indicators. Separate models using mean USD3NB score and the Montreal cognitive assessment (MoCA) total score tested the reproducibility of the incremental value of IIV-d over-and-above global cognition. Binary logistic regressions tested whether IIV-d could classify individuals with and without clinician-rated cognitive fluctuations. Multinomial logistic regressions tested whether IIV-d could differentiate participants with DLB, participants with Alzheimer's disease (AD), and participants with healthy cognition (CH), as well as the incremental diagnostic utility of IIV-d over-and-above clinician-rated cognitive fluctuations.

RESULTS

IIV-d exhibited large univariate associations with clinician-rated and non-clinician-informant reported cognitive fluctuations, which persisted when adjusting for MoCA but not the full battery mean. Of diagnostic relevance, greater IIV-d was consistently associated with DLB and AD relative to CH over-and-above global cognition and clinician-rated cognitive fluctuations. Greater IIV-d was less consistently associated with an increased probability of DLB relative to AD when controlling for global cognition.

CONCLUSIONS

IIV-d accurately differentiates DLB from CH over-and-above global cognition and clinician-rated cognitive fluctuations. IIV-d may supplement a thorough clinical interview of cognitive fluctuations and serve as a standardized performance-based indicator of this transdiagnostic phenomenon. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Cultural Adaptation of Cognitive Stimulation Therapy (CST) for Portuguese People with Dementia

OBJECTIVES

Portugal is one of the most aged countries in the world and dementia is increasing among the Portuguese population. It is estimated to affect around 200,000 people in Portugal. There is a clear need for non-pharmacological interventions to ameliorate the symptoms of dementia and improve the quality of life. Cognitive Stimulation Therapy (CST), a worldwide well-known program developed in the United Kingdom (UK), is recognized as a cost-effective intervention, with benefits both in cognitive function and quality of life of people with mild to moderate dementia. We tested the feasibility and cultural appropriateness and adapted CST to Portuguese people with dementia.

METHODS

The Formative Method for Adapting Psychotherapy (FMAP) model for cultural adaptation was used. A focus group discussion with health professionals and caregivers provided the basis for cultural adaptation, as well as feedback from participants, caregivers, and facilitators after a pilot study.

RESULTS

Some modifications were required, especially related to linguistic issues, in 11 of the 14 CST sessions. The adapted program was found to be acceptable and enjoyable in a small sample of people with dementia in a rehabilitation context.

CONCLUSIONS

CST seems feasible and culturally appropriate in Portugal. A systematically developed and culturally adapted manual is ready to be used in a large-scale implementation and validation of CST in Portugal.

CLINICAL IMPLICATIONS

CST is a valid program for the Portuguese culture, contributes to the availability of a structured and effective clinical intervention for PwD in Portugal and to the possibility of comparing programs across countries.

Elevated Plasma Orexin-A Levels in Prodromal Dementia with Lewy Bodies

BACKGROUND

Studies on plasma orexin-A levels in prodromal dementia with Lewy bodies (DLB) and the relationship with clinical manifestations are rare.

OBJECTIVE

To assess plasma orexin-A levels and evaluate the correlation with clinical features in patients with mild cognitive impairment with Lewy bodies (MCI-LB) and DLB.

METHODS

Plasma orexin-A levels were measured in 41 patients with MCI-LB, 53 with DLB, and 48 healthy controls (HCs). Informant-based history, neurological examinations, neuropsychological assessments, laboratory tests, and neuroimaging were collected and the correlation between orexin-A and various indicators evaluated.

RESULTS

Plasma orexin-A levels in patients with MCI-LB (1.18±0.33 ng/mL, p = 0.014) or DLB (1.20±0.44 ng/mL, p = 0.011) were significantly higher than in HCs (1.02±0.32 ng/mL) and associated with gender and age. DLB patients with fluctuating cognition (FC) (1.01±0.23 versus 1.31±0.50, p = 0.007) or parkinsonism (PARK) (0.98±0.19 versus 1.25±0.47, p = 0.030) had significantly lower plasma orexin-A levels than subjects without FC or PARK. Plasma orexin-A levels were significantly negatively correlated with irritability and UPDRS-III scores and significantly positively correlated with disinhibition scores.

CONCLUSION

This is the first report in which elevated plasma orexin-A levels were observed in patients with MCI-LB or DLB. In addition, lower orexin-A levels were found in patients with DLB and FC or PARK compared with HCs. The plasma orexin-A levels were associated with the presence of core features and motor and neuropsychiatric symptoms in patients with MCI-LB and DLB.

Current Therapies and Drug Development Pipeline in Lewy Body Dementia: An Update

The term Lewy body dementia refers to either of two related diagnoses: dementia with Lewy bodies (DLB) and Parkinson's disease dementia (PDD). Clinical management of Lewy body dementia is challenging. The current treatment options focus on relieving symptoms; no disease-modifying therapies are available. There are currently no US Food and Drug Administration (FDA) approved drugs for the treatment of DLB, and there are only a few for PDD. Cholinesterase inhibitors are shown to be beneficial in improving cognitive symptoms in Lewy body dementia. Rivastigmine was approved by the FDA to treat PDD. Donepezil was approved in Japan as a treatment for DLB. Levodopa may provide modest benefit in treating motor symptoms and zonisamide in adjunct to low-dose levodopa helps with parkinsonism. Treatment of autonomic symptoms are based on symptomatic treatment with off-label agents. Our main objective in this article is to present an overview of the current pharmacological options available to treat the clinical features of DLB and PDD. When evaluating the existing management options for Lewy body dementia, it is difficult to fully separate PDD from DLB. However, we have attempted to identify whether the cited studies include patients with PDD and/or DLB. Moreover, we have provided an overview of the current drug pipeline in Lewy body dementia. All currently active trials are in phase I or II and most are focused on disease modification rather than symptomatic treatment. Phase II trial results for neflamapimod show promising results. Due to heterogeneity of symptoms and underlying pathophysiology, there is a need for new biomarker strategies and improved definitions of outcome measures for Lewy body dementia drug trials.

Caring for patients with cognitive dysfunction, fluctuations and dementia caused by Parkinson's disease

Cognitive dysfunction is one of the most prevalent non-motor symptoms in patients with Parkinson's disease (PD). While it tends to worsen in the later stages of disease, it can occur at any time, with 15-20% of patients exhibiting cognitive deficits at diagnosis (Aarsland et al., 2010; Goldman and Sieg, 2020). The characteristic features of cognitive dysfunction include impairment in executive function, visuospatial abilities, and attention, which vary in severity from subtle impairment to overt dementia (Martinez-Horta and Kulisevsky, 2019). To complicate matters, cognitive dysfunction is prone to fluctuate in PD patients, impacting diagnosis and the ability to assess progression and decision-making capacity. The diagnosis of cognitive impairment or dementia has a huge impact on patient independence, quality of life, life expectancy and caregiver burden (Corallo et al., 2017; Lawson et al., 2016; Leroi et al., 2012). It is therefore essential that physicians caring for patients with PD provide education, screening and treatment for this aspect of the disease. In this chapter, we provide a practical guide for the assessment and management of various degrees of cognitive dysfunction in patients with PD by approaching the disease at different stages. We address risk factors for cognitive dysfunction, prevention strategies prior to making the diagnosis, available tools for screening. Lastly, we review aspects of care, management and considerations, including decision-making capacity, that occur after the patient has been diagnosed with cognitive dysfunction or dementia.

Dynamic network impairments underlie cognitive fluctuations in Lewy body dementia

Cognitive fluctuations are a characteristic and distressing disturbance of attention and consciousness seen in patients with Dementia with Lewy bodies and Parkinson's disease dementia. It has been proposed that fluctuations result from disruption of key neuromodulatory systems supporting states of attention and wakefulness which are normally characterised by temporally variable and highly integrated functional network architectures. In this study, patients with DLB (n = 25) and age-matched controls (n = 49) were assessed using dynamic resting state fMRI. A dynamic network signature of reduced temporal variability and integration was identified in DLB patients compared to controls. Reduced temporal variability correlated significantly with fluctuation-related measures using a sustained attention task. A less integrated (more segregated) functional network architecture was seen in DLB patients compared to the control group, with regions of reduced integration observed across dorsal and ventral attention, sensorimotor, visual, cingulo-opercular and cingulo-parietal networks. Reduced network integration correlated positively with subjective and objective measures of fluctuations. Regions of reduced integration and unstable regional assignments significantly matched areas of expression of specific classes of noradrenergic and cholinergic receptors across the cerebral cortex. Correlating topological measures with maps of neurotransmitter/neuromodulator receptor gene expression, we found that regions of reduced integration and unstable modular assignments correlated significantly with the pattern of expression of subclasses of noradrenergic and cholinergic receptors across the cerebral cortex. Altogether, these findings demonstrate that cognitive fluctuations are associated with an imaging signature of dynamic network impairment linked to specific neurotransmitters/neuromodulators within the ascending arousal system, highlighting novel potential diagnostic and therapeutic approaches for this troubling symptom.

Quantifying test-retest reliability of repeated objective attentional measures in Lewy body dementia

Objective cognitive impairment is a feature of Lewy body dementia (LBD), and computerised attentional tasks are commonly used as outcome measures in interventional trials. However, the reliability of these measures, in the absence of interventions, are unknown. This study examined the reliability of these attentional measures at short-term and longer-term follow-up stages. LBD patients (n = 36) completed computerised attentional tasks [simple and choice reaction time, and digit vigilance (SRT, CRT, DV)] at short-term (Day 0–Day 5) and longer-term (4 and 12 weeks) follow-up. Intra-class correlations (ICCs) were calculated to assess test–retest reliability. At short-term, the reciprocal SRT, CRT and DV mean reaction time to correct answers, the reciprocal DV coefficient of variation, and reciprocal power of attention (PoA) all showed excellent levels of reliability (all ICCs > 0.90). The reciprocal PoA showed the highest level of reliability (ICC = 0.978). At longer-term follow-up, only the reciprocal PoA had excellent levels of reliability (ICC = 0.927). Reciprocal SRT, CRT and DV reaction time to correct answers, and the CRT coefficient of variation values, showed good levels of test–retest reliability (ICCs ≥ 0.85). Contrary to expectations, most attentional measures demonstrated high levels of test–retest reliability at both short-term and longer-term follow-up time points. The reciprocal PoA composite measure demonstrated excellent levels of test–retest reliability, both in the short-term and long-term. This indicates that objective attentional tasks are suitable outcome measures in LBD studies and that the composite PoA measure may offer the highest levels of reliability.

α-Synuclein-mediated neurodegeneration in Dementia with Lewy bodies: the pathobiology of a paradox

Dementia with Lewy bodies (DLB) is epitomized by the pathognomonic manifestation of α-synuclein-laden Lewy bodies within selectively vulnerable neurons in the brain. By virtue of prion-like inheritance, the α-synuclein protein inexorably undergoes extensive conformational metamorphoses and culminate in the form of fibrillar polymorphs, instigating calamitous damage to the brain's neuropsychological networks. This epiphenomenon is nebulous, however, by lingering uncertainty over the quasi "pathogenic" behavior of α-synuclein conformers in DLB pathobiology. Despite numerous attempts, a monolithic "α-synuclein" paradigm that is able to untangle the enigma enshrouding the clinicopathological spectrum of DLB has failed to emanate. In this article, we review conceptual frameworks of α-synuclein dependent cell-autonomous and non-autonomous mechanisms that are likely to facilitate the transneuronal spread of degeneration through the neuraxis. In particular, we describe how the progressive demise of susceptible neurons may evolve from cellular derangements perpetrated by α-synuclein misfolding and aggregation. Where pertinent, we show how these bona fide mechanisms may mutually accentuate α-synuclein-mediated neurodegeneration in the DLB brain.

Muscarinic Receptors Expression in the Peripheral Blood Cells Differentiate Dementia with Lewy Bodies from Alzheimer's Disease

BACKGROUND

Central nervous system disruption of cholinergic (ACh) signaling, which plays a major role in cognitive processes, is well documented in dementia with Lewy bodies (DLB) and Alzheimer's disease (AD). The expression of muscarinic ACh receptors type 1 and 4 (CHRM1 and CHRM4) has been reported to be altered in the brain of DLB patients.

OBJECTIVE

We aim to assess the peripheral gene expression of CHRM1 and 4 in DLB as a possible marker as compared to AD and healthy control (HC) subjects.

METHODS

Peripheral blood mononuclear cells were collected from 21 DLB, 13 AD, and 8 HC matched subjects. RT-PCR was performed to estimate gene expression of CHRM1 and CHRM4.

RESULTS

Peripheral CHRM1 expression was higher and CHRM4 was lower in DLB and AD compared to HC, whereas both CHRM1 and CHRM4 levels were higher in AD compared to DLB patients. Receiver operating characteristics curves, with logistic regression analysis, showed that combining peripheral CHRM1 and CHRM4 levels, DLB and AD subjects were classified with an accuracy of 76.0%.

CONCLUSION

Alterations of peripheral CHRM1 and CHRM4 was found in both AD and DLB patients as compared to HC. CHRM1 and CHRM4 gene expression resulted to be lower in DLB patients compared to AD. In the future, peripheral CHRM expression could be studied as a possible marker of neurodegenerative conditions associated with cholinergic deficit and a possible marker of response to acetylcholinesterase inhibitors.

Challenges in Predicting Cognitive Decline in Dementia with Lewy Bodies

Despite being the second most common form of neurodegenerative dementia, dementia with Lewy bodies (DLB) is under-recognized and carries a worse prognosis than other subtypes of the condition. Cognitive impairment is a cardinal feature of all types of dementia and DLB presents with a distinct profile with deficits in attention, executive function, and visuoperceptual abilities. This difference from Alzheimer's disease and the common presence of neuropsychiatric symptoms may lead to challenges in predicting cognitive decline in this patient population. Firstly, the diagnosis of DLB is often delayed in clinical practice leading to variability from which time point in the disease course cognitive decline is measured. Secondly, the most frequently used measurement tools for cognitive difficulties focus on memory and naming rather than the domains affected by DLB. While there is now largely a consensus which tools are useful in diagnosing DLB, their validity in assessing deteriorating cognition is less clear. Thirdly, the presence of fluctuating cognition, the propensity to develop delirium episodes, as well as difficulties in distinguishing the two entities in clinical practice make it difficult to predict the disease course. Sleep disturbances are likely to influence cognitive decline but require further study in patients within established DLB. Fourthly, as in most cases of dementia, neuropathological comorbidities are frequently present in DLB. While the influence of Alzheimer's pathology on cognitive decline in DLB is comparatively well understood, the impact of other pathologies remains unclear. The recent definition of research criteria for mild cognitive impairment in DLB could facilitate earlier diagnosis and more structured follow-up. Assessment tools measuring cognitive domains predominantly affected in DLB need to be more consistently used in longitudinal studies and clinical practice, as well as concurrent measures of fluctuations in cognition. Greater availability of biomarkers and digital healthcare solutions can play an important role in enabling more accurate monitoring and prediction of cognitive decline in DLB.

Intrinsic Alertness Is Impaired in Patients with Nigrostriatal Degeneration: A Prospective Study with Reference to [123I]FP-CIT SPECT and [18F]FDG PET

BACKGROUND

Variations in alertness and attention are common in Lewy body diseases (LBD) and among the core features of dementia with Lewy bodies (DLB). Dopamine transporter SPECT is an accurate biomarker of nigrostriatal degeneration (NSD) in LBD.

OBJECTIVE

The present study investigated performance on a computerized alertness test as a potential measure of attention in patients with NSD compared to patients without NSD.

METHODS

Thirty-six patients with cognitive impairment plus at least one core feature of DLB referred for [123I]FP-CIT SPECT imaging were prospectively recruited. Performance in a computerized test of intrinsic alertness was compared between patients with and those without NSD as assessed by [123I]FP-CIT SPECT.

RESULTS

Reaction times to auditory stimuli (adjusted for age, sex, and education) were significantly longer in patients with NSD compared to those with a normal [123I]FP-CIT SPECT scan (p < 0.05). Statistical analyses revealed no significant differences comparing reaction times to visual stimuli or dispersion of reaction times between groups. Exploratory analysis in a subgroup of patients with available [18F]FDG PET revealed that longer reaction times were associated with decreased glucose metabolism in the prefrontal cortex (statistical parametric mapping, adjusted for age and sex; p < 0.005, cluster extent > 50 voxels).

CONCLUSION

Computerized assessment of auditory reaction times is able to detect alertness deficits in patients with NSD and might help to measure alertness deficits in patients with LBD and NSD. Future studies in larger samples are needed to evaluate the diagnostic utility of computerized alertness assessment for the differential diagnosis of LBD.

Impaired sensory evidence accumulation and network function in Lewy body dementia

Deficits in attention underpin many of the cognitive and neuropsychiatric features of Lewy body dementia. These attention-related symptoms remain difficult to treat and there are many gaps in our understanding of their neurobiology. An improved understanding of attention-related impairments can be achieved via mathematical modelling approaches, which identify cognitive parameters to provide an intermediate level between observed behavioural data and its underlying neural correlate. Here, we apply this approach to identify the role of impaired sensory evidence accumulation in the attention deficits that characterize Lewy body dementia. In 31 people with Lewy body dementia (including 13 Parkinson's disease dementia and 18 dementia with Lewy bodies cases), 16 people with Alzheimer's disease, and 23 healthy controls, we administered an attention task whilst they underwent functional 3 T MRI. Using hierarchical Bayesian estimation of a drift-diffusion model, we decomposed task performance into drift rate and decision boundary parameters. We tested the hypothesis that the drift rate-a measure of the quality of sensory evidence accumulation-is specifically impaired in Lewy body dementia, compared to Alzheimer's disease. We further explored whether trial-by-trial variations in the drift rate related to activity within the default and dorsal attention networks, to determine whether altered activity in these networks was associated with slowed drift rates in Lewy body dementia. Our results revealed slower drift rates in the Lewy body dementia compared to the Alzheimer's disease group, whereas the patient groups were equivalent for their decision boundaries. The patient groups were reduced relative to controls for both parameters. This highlights sensory evidence accumulation deficits as a key feature that distinguishes attention impairments in Lewy body dementia, consistent with impaired ability to efficiently process information from the environment to guide behaviour. We also found that the drift rate was strongly related to activity in the dorsal attention network across all three groups, whereas the Lewy body dementia group showed a divergent relationship relative to the Alzheimer's disease and control groups for the default network, consistent with altered default network modulation being associated with impaired evidence accumulation. Together, our findings reveal impaired sensory evidence accumulation as a specific marker of attention problems in Lewy body dementia, which may relate to large-scale network abnormalities. By identifying impairments in a specific sub-process of attention, these findings will inform future exploratory and intervention studies that aim to understand and treat attention-related symptoms that are a key feature of Lewy body dementia.

EEG measures for clinical research in major vascular cognitive impairment: recommendations by an expert panel

Vascular contribution to cognitive impairment (VCI) and dementia is related to etiologies that may affect the neurophysiological mechanisms regulating brain arousal and generating electroencephalographic (EEG) activity. A multidisciplinary expert panel reviewed the clinical literature and reached consensus about the EEG measures consistently found as abnormal in VCI patients with dementia. As compared to cognitively unimpaired individuals, those VCI patients showed (1) smaller amplitude of resting state alpha (8-12 Hz) rhythms dominant in posterior regions; (2) widespread increases in amplitude of delta (< 4 Hz) and theta (4-8 Hz) rhythms; and (3) delayed N200/P300 peak latencies in averaged event-related potentials, especially during the detection of auditory rare target stimuli requiring participants' responses in "oddball" paradigms. The expert panel formulated the following recommendations: (1) the above EEG measures are not specific for VCI and should not be used for its diagnosis; (2) they may be considered as "neural synchronization" biomarkers to enlighten the relationships between features of the VCI-related cerebrovascular lesions and abnormalities in neurophysiological brain mechanisms; and (3) they may be tested in future clinical trials as prognostic biomarkers and endpoints of interventions aimed at normalizing background brain excitability and vigilance in wakefulness.

An international, randomized, placebo-controlled, phase 2b clinical trial of intepirdine for dementia with Lewy bodies (HEADWAY-DLB)

INTRODUCTION

A phase 2b clinical trial, HEADWAY-DLB, was performed to assess treatment with intepirdine, a serotonin receptor antagonist, in patients with dementia with Lewy bodies (DLB).

METHODS

HEADWAY-DLB was a multinational, double-blind, randomized, placebo-controlled study. Two hundred sixty-nine DLB patients were randomized to receive placebo, 70 mg/day intepirdine, or 35 mg/day intepirdine over 24 weeks. The primary endpoint was change from baseline to week 24 on the Unified Parkinson's Disease Rating Scale-Part III (UPDRS-III).

RESULTS

Both intepirdine groups did not demonstrate significant benefits over placebo at 24 weeks on the UPDRS-III (35 mg/day: P = .1580, 70 mg/day: P = .6069). All other endpoints were not significant. Intepirdine was well tolerated, with a slightly higher incidence of gastrointestinal adverse events observed in the intepirdine groups versus placebo.

DISCUSSION

Intepirdine treatment did not lead to improvements over placebo in patients with DLB. As one of the largest DLB studies to date, HEADWAY-DLB demonstrates that international trials for DLB are feasible within a reasonable timeframe.

Added Value of QEEG for the Differential Diagnosis of Common Forms of Dementia

INTRODUCTION

Quantitative electroencephalography (QEEG) has been documented as a helpful tool in the differential diagnosis of Alzheimer's disease (AD) with common forms of dementia. The main objective of the study was to assess the role of QEEG in AD differential diagnosis with other forms of dementia: Lewy body dementia (LBD), Parkinson's disease dementia (PDD), frontotemporal dementia (FTD), and vascular dementia (VaD).

METHODS

We searched PubMed, Embase, and PsycNET, for articles in English published in peer-reviewed journals from January 1, 1980 to April 23, 2019 using adapted search strategies containing keywords quantitative EEG and Alzheimer. The risk of bias was assessed by applying the QUADAS tool. The systematic review was conducted in line with the PRISMA methodology.

RESULTS

We identified 10 articles showcasing QEEG features used in diagnosing dementia, EEG slowing phenomena in AD and PDD, coherence changes in AD and VaD, the role of LORETA in dementia, and the controversial QEEG pattern in FTD. Results vary significantly in terms of sociodemographic features of the studied population, neuropsychological assessment, signal acquisition and processing, and methods of analysis.

DISCUSSION

This article provides a comparative synthesis of existing evidence on the role of QEEG in diagnosing dementia, highlighting some specific features for different types of dementia (eg, the slow-wave activity has been remarked in both AD and PDD, but more pronounced in PDD patients, a diminution in anterior and posterior alpha coherence was noticed in AD, and a lower alpha coherence in the left temporal-parietal-occipital regions was observed in VaD).

CONCLUSION

QEEG may be a useful investigation for settling the diagnosis of common forms of dementia. Further research of quantitative analyses is warranted, particularly on the association between QEEG, neuropsychological, and imaging features. In conjunction, these methods may provide superior diagnostic accuracy in the diagnosis of dementia.

Electroencephalogram in dementia with Lewy bodies: a systematic review

Dementia with Lewy bodies (DLB) belongs to the spectrum of Lewy body dementia (LBD) that also encompasses Parkinson's disease dementia (PDD). It is a common neurodegenerative disorder characterized by memory decline, cognitive fluctuations, visual hallucinations, autonomic nervous system disturbance, REM sleep behavior disorder, and parkinsonism. Definite diagnosis can be established only through neuropathological confirmation of Lewy bodies' presence in brain tissue. Probable or possible diagnosis relies upon clinical features, imaging, polysomnography, and electroencephalogram (EEG) findings. Potential neurophysiological biomarkers for the diagnosis, management, and evaluation of treatment-response in DLB should be affordable and widely available outside academic centers. Increasing evidence supports the use of quantitative EEG (qEEG) as a potential DLB biomarker, with promising results in discriminating DLB from other dementias and in identifying subjects who are on the trajectory to develop DLB. Several studies evaluated the diagnostic value of EEG in DLB. Visual analysis and qEEG techniques have been implemented, showing a superiority of the last in terms of sensitivity and objectivity. In this systematic review, we attempt to provide a general synthesis of the current knowledge on EEG application in DLB. We review the findings from original studies and address the issues remaining to be further clarified.

Measures of resting state EEG rhythms for clinical trials in Alzheimer's disease: Recommendations of an expert panel

The Electrophysiology Professional Interest Area (EPIA) and Global Brain Consortium endorsed recommendations on candidate electroencephalography (EEG) measures for Alzheimer's disease (AD) clinical trials. The Panel reviewed the field literature. As most consistent findings, AD patients with mild cognitive impairment and dementia showed abnormalities in peak frequency, power, and "interrelatedness" at posterior alpha (8-12 Hz) and widespread delta (< 4 Hz) and theta (4-8 Hz) rhythms in relation to disease progression and interventions. The following consensus statements were subscribed: (1) Standardization of instructions to patients, resting state EEG (rsEEG) recording methods, and selection of artifact-free rsEEG periods are needed; (2) power density and "interrelatedness" rsEEG measures (e.g., directed transfer function, phase lag index, linear lagged connectivity, etc.) at delta, theta, and alpha frequency bands may be use for stratification of AD patients and monitoring of disease progression and intervention; and (3) international multisectoral initiatives are mandatory for regulatory purposes.

Evaluating the Sustained Attention Response Task to Quantify Cognitive Fluctuations in Dementia With Lewy Bodies

Cognitive fluctuations (CFs) are a core diagnostic feature of dementia with Lewy bodies (DLB). Detection of CF is still mostly based on subjective reports from the patient or informant; more quantitative measures are likely to improve the accuracy for the diagnosis of DLB. The purpose of the current study is to test whether performance on the Sustained Attention Response Task (SART) could distinguish those patients with DLB with and without CF. Twenty-four patients with DLB were tested on the SART and performance was related to scores on the Clinical Assessment of Fluctuations (CAFs) and One Day Fluctuation Assessment Scale (ODFAS). The number of "misses" made was a significant predictor of their fluctuation severity, attentional performance, disorganized thinking, and language production ratings on the ODFAS. However, measures on the SART did not correlate with measures on the CAF scale. In conclusion, these findings suggest that SART is a feasible measure of sustained attention in this population and has clinical and diagnostic relevance to the measurement of CF, particularly those aspects measured by the ODFAS.

Delirium Superimposed on Dementia in Perioperative Period and Intensive Care

Delirium is a life-threatening condition, the causes of which are still not fully understood. It may develop in patients with pre-existing dementia. Delirium superimposed on dementia (DSD) can go completely unnoticed with routine examination. It may happen in the perioperative period and in the critical care setting, especially in the ageing population. Difficulties in diagnosing and lack of specific pharmacological and non-pharmacological treatment make DSD a seriously growing problem. Patient-oriented, multidirectional preventive measures should be applied to reduce the risk of DSD. For this reason, anesthesiologists and intensive care specialists should be aware of this interesting condition in their everyday clinical practice.

The Role of EEG in the Diagnosis, Prognosis and Clinical Correlations of Dementia with Lewy Bodies-A Systematic Review

Despite improvements in diagnostic criteria for dementia with Lewy bodies (DLB), the ability to discriminate DLB from Alzheimer’s disease (AD) and other dementias remains suboptimal. Electroencephalography (EEG) is currently a supportive biomarker in the diagnosis of DLB. We performed a systematic review to better clarify the diagnostic and prognostic role of EEG in DLB and define the clinical correlates of various EEG features described in DLB. MEDLINE, EMBASE, and PsycINFO were searched using search strategies for relevant articles up to 6 August 2020. We included 43 studies comparing EEG in DLB with other diagnoses, 42 of them included a comparison of DLB with AD, 10 studies compared DLB with Parkinson’s disease dementia, and 6 studies compared DLB with other dementias. The studies were visual EEG assessment (6), quantitative EEG (35) and event-related potential studies (2). The most consistent observation was the slowing of the dominant EEG rhythm (<8 Hz) assessed visually or through quantitative EEG, which was observed in ~90% of patients with DLB and only ~10% of patients with AD. Other findings based on qualitative rating, spectral power analyses, connectivity, microstate and machine learning algorithms were largely heterogenous due to differences in study design, EEG acquisition, preprocessing and analysis. EEG protocols should be standardized to allow replication and validation of promising EEG features as potential biomarkers in DLB.

Direct Medical Costs of Dementia With Lewy Bodies by Disease Complexity

OBJECTIVES

There is currently no accurate profile of the economic burden of dementia with Lewy bodies (DLB), particularly any examination of the direct medical costs of DLB by the number of affected clinical domains. Understanding how trends in the use of healthcare resources evolve as DLB progresses presents opportunities for the development of earlier and more appropriate interventions.

DESIGN

Retrospective study using claims data extracted from the IBM MarketScan Commercial and Medicare Supplemental database.

SETTING AND PARTICIPANTS

In total, 536 patients with DLB from the Commercial database and 5485 patients with DLB from the Medicare Supplemental database.

METHODS

Patients were grouped into disease complexity categories based on core clinical features (ie, fluctuating cognition, motor symptoms, visual hallucinations, and rapid eye movement sleep behavior disorder in addition to dementia) observed during the study period: dementia with no core features observed, dementia plus 1, 2, or ≥3 core features, respectively. Outcome measures included healthcare resource utilization and healthcare costs.

RESULTS

In both databases, total healthcare resource utilization and costs increased with number of core features. Compared with patients with no core features observed, patients in all other complexity categories had significantly higher mean medical visits and costs in both adjusted and unadjusted analyses. Fluctuating cognition was associated with the highest total costs, suggesting that this clinical feature in particular is associated with a considerable economic burden.

CONCLUSIONS AND IMPLICATIONS

Analyzing direct medical costs of DLB by disease complexity using claims data showed that a higher cost impact was associated with increasing number of clinical domains affected and with specific clinical domains, suggesting the need for both targeted and comprehensive interventions to improve the overall economic burden of DLB.

Quantitative EEG as a biomarker in mild cognitive impairment with Lewy bodies

Objectives

To investigate using quantitative EEG the (1) differences between patients with mild cognitive impairment with Lewy bodies (MCI-LB) and MCI with Alzheimer’s disease (MCI-AD) and (2) its utility as a potential biomarker for early differential diagnosis.

Methods

We analyzed eyes-closed, resting-state, high-density EEG data from highly phenotyped participants (39 MCI-LB, 36 MCI-AD, and 31 healthy controls). EEG measures included spectral power in different frequency bands (delta, theta, pre-alpha, alpha, and beta), theta/alpha ratio, dominant frequency, and dominant frequency variability. Receiver operating characteristic (ROC) analyses were performed to assess diagnostic accuracy.

Results

There was a shift in power from beta and alpha frequency bands towards slower frequencies in the pre-alpha and theta range in MCI-LB compared to healthy controls. Additionally, the dominant frequency was slower in MCI-LB compared to controls. We found significantly increased pre-alpha power, decreased beta power, and slower dominant frequency in MCI-LB compared to MCI-AD. EEG abnormalities were more apparent in MCI-LB cases with more diagnostic features. There were no significant differences between MCI-AD and controls. In the ROC analysis to distinguish MCI-LB from MCI-AD, beta power and dominant frequency showed the highest area under the curve values of 0.71 and 0.70, respectively. While specificity was high for some measures (up to 0.97 for alpha power and 0.94 for theta/alpha ratio), sensitivity was generally much lower.

Conclusions

Early EEG slowing is a specific feature of MCI-LB compared to MCI-AD. However, there is an overlap between the two MCI groups which makes it difficult to distinguish between them based on EEG alone.

Evaluation of decision-making capacity in patients with dementia: challenges and recommendations from a secondary analysis of qualitative interviews

Background

Evaluation of decision-making capacity to consent to medical treatment has proved to be difficult in patients with dementia. Studies showed that physicians are often insufficiently trained in the evaluation of decision-making capacity. In this study, we present findings from a secondary analysis of a qualitative interviews with physicians. These interviews were initially used to assess usability of an instrument for the evaluation of decision-making capacity. By looking at difficult cases of decision-making capacity evaluation in patients with dementia, we provide recommendations for such evaluations in clinical practice.

Methods

We used thematic coding to analyse physicians’ narratives of problematic decision-making capacity evaluations in patients with dementia to uncover challenging issues of decision-making capacity evaluation.

Results

In this study, decision-making capacity evaluations in patients with dementia were mainly perceived as challenging when they pertained to treatment refusals and treatment unrelated circumstances, such as psychiatric consultation, advance directives, and new living arrangements. Furthermore, the physicians reported training needs regarding situation-independent challenges with decision-making capacity evaluation.

Conclusions

Upon further examining self-reported training needs and challenging cases, we have developed recommendations to improve decision-making capacity evaluations in clinical practice. In these recommendations, we argue that being able to evaluate decision-making capacity is an integral part of the informed consent process.

The Neuropsychological Profile of Attention Deficits of Patients with Obstructive Sleep Apnea: An Update on the Daytime Attentional Impairment

Introduction: Patients with obstructive sleep apnea (OSA) suffer from several neurocognitive disturbances. One of the neuropsychological processes most investigated in OSA patients is attention, but the results have been controversial. Here, we update the attention profile of OSA patients with the final aim to improve attention assessment, with a possible impact on clinical and medical-legal practices, in terms of which attention subdomains and parameters need consideration and which one is a high-risk OSA phenotype for attention dysfunctions. Method: For this purpose, we assessed 32 previously untreated OSA patients (26 men and 6 women) under 65 years of age (mean age 53.2 ± 7.3; mean education level 10.4 ± 3.4 years) suffering from moderate to severe sleep apnea and hypopnea (mean apnea-hypopnea index (AHI) 45.3 ± 22.9, range 16.1–69.6). A control group of 34 healthy participants matched with OSA patients for age, education level, and general cognitive functioning were also enrolled. The OSA patients and healthy participants were tested through an extensive computerized battery (Test of Attentional Performance, TAP) that evaluated intensive (i.e., alertness and vigilance) and selective (i.e., divided and selective) dimensions of attention and returned different outcome parameters (i.e., reaction time, stability of performance, and various types of errors). Data analysis: The data were analyzed by ANCOVA which compared the speed and accuracy performance of the OSA and control participants (cognitive reserve was treated as a covariate). The possible mechanisms underlying attention deficits in OSA patients were examined through correlation analysis among AHI, oxygenation parameters, sleepiness scores, and TAP outcomes and by comparing the following three phenotypes of patients: severe OSA and severe nocturnal desaturators (AHI⁺⁺D⁺), severe OSA nondesaturators (AHI⁺⁺D⁻), and moderate OSA nondesaturators (AHI⁺D⁻). Results: The results suggest that the OSA patients manifest deficits in both intensive and selective attention processes and that reaction time (RT) alone is ineffective for detecting and characterizing their problems, for which error analysis and stability of performance also have to be considered. Patients with severe OSA and severe hypoxemia underperformed on alertness and vigilance attention subtests. Conclusions: The data suggest the importance of evaluating attention deficits among OSA patients through several parameters (including performance instability). Moreover, the data suggest a multifaceted mechanism underlying attention dysfunction in OSA patients.

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 drug development for dementia with Lewy bodies: past and present

Introduction: Dementia with Lewy bodies (DLB) is an under-researched area despite being the second most common type of degenerative dementia after Alzheimer's disease. It is an area of unmet need with no approved symptomatic or disease-modifying therapies. The pharmacological management of DLB is complex and challenging because early trials of drugs for DLB have resulted in no demonstrable efficacy. Randomized controlled trials (RCTs) in the DLB population have only recently been initiated. Understanding results from previous and current clinical trials in DLB can provide insights for future research and development.Areas covered: We provide an overview of the DLB drug development landscape and the current treatment strategies. We reviewed ClinicalTrials.gov to identify all clinical trials for the treatment of DLB.Expert opinion: DLB drug development has significantly improved in recent years with eight agents now in clinical trials. However, more rigorous RCTs are urgently needed. Diagnostic criteria must be optimized to accurately diagnose patients for clinical trials and care. New biomarker strategies are necessary to improve diagnostic capabilities and trial designs, and novel drug targets should be identified to develop DLB specific disease-modifying therapies. Evaluating the current drug development landscape can provide insight into how best to optimize development practices.

Cognitive fluctuations in Lewy body dementia: towards a pathophysiological framework

Fluctuating cognition is a complex and disabling symptom that is seen most frequently in the context of Lewy body dementias encompassing dementia with Lewy bodies and Parkinson’s disease dementia. In fact, since their description over three decades ago, cognitive fluctuations have remained a core diagnostic feature of dementia with Lewy bodies, the second most common dementia in the elderly. In the absence of reliable biomarkers for Lewy body pathology, the inclusion of such patients in therapeutic trials depends on the accurate identification of such core clinical features. Yet despite their diagnostic relevance, cognitive fluctuations remain poorly understood, in part due to the lack of a cohesive clinical and scientific explanation of the phenomenon itself. Motivated by this challenge, the present review examines the history, clinical phenomenology and assessment of cognitive fluctuations in the Lewy body dementias. Based on these data, the key neuropsychological, neurophysiological and neuroimaging correlates of cognitive fluctuations are described and integrated into a novel testable heuristic framework from which new insights may be gained.

Common age-related neuropathologies and yearly variability in cognition

Objective

Cognitive variability is a potentially important source of heterogeneity in longitudinal cognitive profiles. We examined the extent to which common age‐related neuropathologies including Lewy bodies and Alzheimer’s disease (AD) contribute to yearly variability in late life cognition.

Methods

Data came from 1321 community‐dwelling older adults who were followed annually for up to 23 years, died and underwent brain autopsy. Cognition was assessed via a comprehensive testing battery. Uniform neuropathologic evaluations assessed burdens of Lewy bodies, AD, infarcts, TDP, hippocampal sclerosis, amyloid angiopathy, atherosclerosis, and arteriolosclerosis. Using mixed effects models, yearly variability in cognition, characterized as within‐person variability of annual cognitive scores, was regressed on the nine neuropathologic indices.

Results

The average age of decedents was 90 years and 69% were female. At autopsy, about two thirds met the pathologic criteria for AD. Neocortical Lewy bodies were present in 13% of the individuals. Other neuropathologic conditions also were common. All neuropathologic indices except for microinfarcts were associated with cognitive decline. Individuals with neocortical Lewy bodies had almost twice the yearly variability in cognition compared to those without. Individuals with AD had about 70% more variability compared to those without. Yearly variability was present among persons with vascular diseases but to a lesser degree than neocortical Lewy bodies and AD.

Interpretation

Lewy body pathology is associated with pronounced variability in annual cognitive assessments but this finding is not unique to this pathology. Comparable variability is present among persons with AD pathology and to a lesser extent among persons with cerebrovascular pathologies.

Hallucinations, somatic-functional disorders of PD-DLB as expressions of thalamic dysfunction

Hallucinations, delusions, and functional neurological manifestations (conversion and somatic symptom disorders) of Parkinson's disease (PD) and dementia with Lewy bodies increase in frequency with disease progression, predict the onset of cognitive decline, and eventually blend with and are concealed by dementia. These symptoms share the absence of reality constraints and can be considered comparable elements of the PD-dementia with Lewy bodies psychosis. We propose that PD-dementia with Lewy bodies psychotic disorders depend on thalamic dysfunction promoting a theta burst mode and subsequent thalamocortical dysrhythmia with focal cortical coherence to theta electroencephalogram rhythms. This theta electroencephalogram activity, also called fast-theta or pre-alpha, has been shown to predict cognitive decline and fluctuations in Parkinson's disease with dementia and dementia with Lewy bodies. These electroencephalogram alterations are now considered a predictive marker for progression to dementia. The resulting thalamocortical dysrhythmia inhibits the frontal attentional network and favors the decoupling of the default mode network. As the default mode network is involved in integration of self-referential information into conscious perception, unconstrained default mode network activity, as revealed by recent imaging studies, leads to random formation of connections that link strong autobiographical correlates to trivial stimuli, thereby producing hallucinations, delusions, and functional neurological disorders. The thalamocortical dysrhythmia default mode network decoupling hypothesis provides the rationale for the design and testing of novel therapeutic pharmacological and nonpharmacological interventions in the context of PD, PD with dementia, and dementia with Lewy bodies. © 2019 International Parkinson and Movement Disorder Society.

Structural correlates of attention dysfunction in Lewy body dementia and Alzheimer's disease: an ex-Gaussian analysis

BACKGROUND

Lewy body dementia (LBD) and Alzheimer's disease (AD) are common forms of degenerative dementia. While they are characterized by different clinical profiles, attentional deficits are a common feature. The objective of this study was to investigate how attentional problems in LBD and AD differentially affect different aspects of reaction time performance and to identify possible structural neural correlates.

METHODS

We studied reaction time data from an attention task comparing 39 LBD patients, 28 AD patients, and 22 age-matched healthy controls. Data were fitted to an ex-Gaussian model to characterize different facets of the reaction time distribution (mean reaction time, reaction time variability, and the subset of extremely slow responses). Correlations between ex-Gaussian parameters and grey and white matter volume were assessed by voxel-based morphometry.

RESULTS

Both dementia groups showed an increase in extremely slow responses. While there was no difference between AD and controls with respect to mean reaction time and variability, both were significantly increased in LBD patients compared to controls and AD. There were widespread correlations between mean reaction time and variability and grey matter loss in AD, but not in LBD.

CONCLUSIONS

This study shows that different aspects of reaction time performance are differentially affected by AD and LBD, with a difference in structural neural correlates underlying the observed behavioural deficits. While impaired attentional performance is linked to brain atrophy in AD, in LBD it might be related to functional or microstructural rather than macrostructural changes.

Pharmacological Management of Dementia with Lewy Bodies

Dementia with Lewy bodies (DLB) is a complex disease that involves a variety of cognitive, behavioral and neurological symptoms, including progressive memory loss, visual hallucinations, parkinsonism, cognitive fluctuations and rapid eye movement sleep behavior disorder (RBD). These symptoms may appear in varying combinations and levels of severity in each patient who is seen in the clinic, making diagnosis and treatment a challenge. DLB is the third most common of all the neurodegenerative diseases behind both Alzheimer’s disease and Parkinson’s disease (PD). The median age of onset for DLB (76.3 years) is younger than that seen in PD dementia (81.4 years). New pathological studies have shown that most DLB patients have variable amounts of Alzheimer’s changes in their brains, explaining the wide variability in this disease’s clinical presentation and clinical course. This review discusses the three cholinesterase inhibitors that have been shown to be effective in managing the cognitive and behavioral symptoms of DLB: rivastigmine, galantamine and donepezil. Memantine is able to improve clinical global impression of change in those with mild to moderate DLB. Levodopa can treat the parkinsonism of some DLB patients, but the dose is often limited due to the fact that it can cause agitation or worsening of visual hallucinations. A recent phase 2 clinical trial showed the benefit of zonisamide when it is added as an adjunct to levodopa for treating DLB parkinsonism. While atypical antipsychotic drugs may not always be helpful as monotherapy in managing the agitation associated with DLB, low doses of valproic acid can be effective when added as an adjunct to drugs like quetiapine. Pimavanserin may prove to be a useful treatment for psychosis in DLB patients, but like other antipsychotic drugs that are used in dementia patients, there is a small increased risk of mortality. RBD, which is a common core clinical feature of DLB, can be managed with either melatonin or clonazepam. Two agents targeting alpha-synuclein (NPT200-11 and ambroxol) currently hold promise as disease-modifying therapies for DLB, but they are yet to be tested in clinical trials. An agent (E2027) that offers hope of neuroprotection by increasing central cyclic guanosine monophosphate (cGMP) levels is currently being examined in clinical trials in DLB patients.

Dysfunctional brain dynamics and their origin in Lewy body dementia

Lewy body dementia includes dementia with Lewy bodies and Parkinson's disease dementia and is characterized by transient clinical symptoms such as fluctuating cognition, which might be driven by dysfunction of the intrinsic dynamic properties of the brain. In this context we investigated whole-brain dynamics on a subsecond timescale in 42 Lewy body dementia compared to 27 Alzheimer's disease patients and 18 healthy controls using an EEG microstate analysis in a cross-sectional design. Microstates are transiently stable brain topographies whose temporal characteristics provide insight into the brain's dynamic repertoire. Our additional aim was to explore what processes in the brain drive microstate dynamics. We therefore studied associations between microstate dynamics and temporal aspects of large-scale cortical-basal ganglia-thalamic interactions using dynamic functional MRI measures given the putative role of these subcortical areas in modulating widespread cortical function and their known vulnerability to Lewy body pathology. Microstate duration was increased in Lewy body dementia for all microstate classes compared to Alzheimer's disease (P < 0.001) and healthy controls (P < 0.001), while microstate dynamics in Alzheimer's disease were largely comparable to healthy control levels, albeit with altered microstate topographies. Correspondingly, the number of distinct microstates per second was reduced in Lewy body dementia compared to healthy controls (P < 0.001) and Alzheimer's disease (P < 0.001). In the dementia with Lewy bodies group, mean microstate duration was related to the severity of cognitive fluctuations (ρ = 0.56, PFDR = 0.038). Additionally, mean microstate duration was negatively correlated with dynamic functional connectivity between the basal ganglia (r = - 0.53, P = 0.003) and thalamic networks (r = - 0.38, P = 0.04) and large-scale cortical networks such as visual and motor networks in Lewy body dementia. The results indicate a slowing of microstate dynamics and disturbances to the precise timing of microstate sequences in Lewy body dementia, which might lead to a breakdown of the intricate dynamic properties of the brain, thereby causing loss of flexibility and adaptability that is crucial for healthy brain functioning. When contrasted with the largely intact microstate dynamics in Alzheimer's disease, the alterations in dynamic properties in Lewy body dementia indicate a brain state that is less responsive to environmental demands and might give rise to the apparent slowing in thinking and intermittent confusion which typify Lewy body dementia. By using Lewy body dementia as a probe pathology we demonstrate a potential link between dynamic functional MRI fluctuations and microstate dynamics, suggesting that dynamic interactions within the cortical-basal ganglia-thalamic loop might play a role in the modulation of EEG dynamics.

Attentional Fluctuations, Cognitive Flexibility, and Bilingualism in Kindergarteners

The idea of a bilingual advantage in aspects of cognitive control-including cognitive flexibility, inhibition, working memory, and attention-is disputed. Using a sample of kindergarten children, the present study investigated associations between bilingualism and cognitive flexibility-a relationship that has shown mixed findings in prior literature. We also extend prior work by exploring relationships between bilingualism and attentional fluctuations, which represent consistency in attentional control and contribute to cognitive performance. To our knowledge, no previous study has explored this association. Theoretically, attentional fluctuations might mediate or moderate the relationship between bilingualism and cognitive flexibility. However, given evidence of null findings from extant literature when confounding variables are adequately controlled and tasks are standardized, we did not expect to find a bilingual advantage in either cognitive flexibility or attentional fluctuations. Our results supported this hypothesis when considering bilingualism both continuously and categorically. The importance of expanding upon mechanistic accounts connecting bilingualism to cognitive improvements is discussed.

The influence of social support and perceived stress on response time inconsistency

OBJECTIVES

Lack of social support and high levels of stress represent potentially modifiable risk factors for cognitive aging. In this study we examined the relationships between these two risk factors and response time inconsistency (RTI), or trial-to-trial variability in choice response time tasks. RTI is an early indicator of declining cognitive health, and examining the influence of modifiable psychosocial risk factors on RTI is important for understanding and promoting cognitive health during adulthood and old age.

METHODS

Using data from a community sample study (n = 317; M_age = 49, range = 19-83), we examined the effects of social support, including size of network and satisfaction with support, global perceived stress, and their interactions on RTI.

RESULTS

Neither size of network nor satisfaction with support was associated with RTI independent of perceived stress. Stress was positively associated with increased RTI on all tasks, independent of social support. Perceived stress did not interact with either dimension of social support to predict RTI, and perceived stress effects were invariant across age and sex.

CONCLUSION

Perceived stress, but not social support, may be a unique and modifiable risk factor for normal and pathological cognitive aging. Discussion focuses on the importance of perceived stress and its impact on RTI in supporting cognitive health in adulthood and old age.

Abnormalities of functional cortical source connectivity of resting-state electroencephalographic alpha rhythms are similar in patients with mild cognitive impairment due to Alzheimer's and Lewy body diseases

Previous evidence has shown different resting-state eyes-closed electroencephalographic delta (<4 Hz) and alpha (8-10.5 Hz) source connectivity in subjects with dementia due to Alzheimer's (ADD) and Lewy body (DLB) diseases. The present study tested if the same differences may be observed in the prodromal stages of mild cognitive impairment (MCI). Here, clinical and resting-state eyes-closed electroencephalographic data in age-, gender-, and education-matched 30 ADMCI, 23 DLBMCI, and 30 healthy elderly (Nold) subjects were available in our international archive. Mini-Mental State Evaluation (MMSE) score was matched in the ADMCI and DLBMCI groups. The eLORETA freeware estimated delta and alpha source connectivity by the tool called lagged linear connectivity (LLC). Area under receiver operating characteristic curve (AUROCC) indexed the classification accuracy among individuals. Results showed that widespread interhemispheric and intrahemispheric LLC solutions in alpha sources were abnormally lower in both MCI groups compared with the Nold group, but with no differences were found between the 2 MCI groups. AUROCCs of LLC solutions in alpha sources exhibited significant accuracies (0.72-0.75) in the discrimination of Nold versus ADMCI-DLBMCI individuals, but not between the 2 MCI groups. These findings disclose similar abnormalities in ADMCI and DLBMCI patients as revealed by alpha source connectivity. It can be speculated that source connectivity mostly reflects common cholinergic impairment in prodromal state of both AD and DLB, before a substantial dopaminergic derangement in the dementia stage of DLB.

Going beyond the mean: Intraindividual variability of cognitive performance in prodromal and early neurodegenerative disorders

OBJECTIVE

Intraindividual variability (IIV), generally defined as short-term variations in behavior, has been proposed as a sign of subtle early impairment in neurodegenerative disorders, presumably associated with the disintegration of neuronal network connectivity. We aim to provide a review of IIV as a sensitive cognitive marker in prodromal neurodegenerative disorders.

METHOD

A narrative review focusing not only on theoretical and methodological definitions, including an overview on the neural correlates of IIV, but mainly on results from population-based and clinical-based studies on the role of IIV as a reliable predictor of mild cognitive impairment (MCI) and conversion to dementia in neurodegenerative disorders, mostly Alzheimer's and Parkinson's disease.

RESULTS

Most studies focus on MCI and Alzheimer's disease and demonstrate that IIV is a reliable cognitive marker. IIV is partly more sensitive than mean performance in the prediction of cognitive impairment or progressive deterioration and is independent of socio-demographic variables and disease mediators (e.g., genetic susceptibility). Neuroimaging data, mostly from healthy subjects, suggest a relationship between IIV and dysfunction of the default mode network, presumably mediated by white matter disintegration in frontal and parietal areas.

CONCLUSIONS

IIV measures may provide valuable information about diagnosis and progression in prodromal stages of neurodegenerative disorders. Thus, further conceptual and methodological clarifications are needed to justify the inclusion of IIV as a sensible cognitive marker in routine clinical neuropsychological assessment.

Structural Brain Correlates of Attention Dysfunction in Lewy Body Dementias and Alzheimer's Disease

Lewy body dementia (LBD) and Alzheimer's disease (AD) are common forms of dementia that have different clinical profiles but are both commonly associated with attentional deficits. The aim of this study was to investigate efficiency of different attentional systems in LBD and AD and its association with brain structural abnormalities. We studied reaction time (RT) data from 45 LBD, 31 AD patients and 22 healthy controls (HCs) using the Attention Network Test (ANT) to assess the efficiency of three different attentional systems: alerting, orienting and executive conflict. Voxel-based morphometry (VBM) was used to investigate relations between different attention components and cortical volume. Both dementia groups showed slower overall RTs than controls, with additional slowing in LBD relative to AD. There was a significant alerting effect in controls which was absent in the dementia groups, the executive conflict effect was greater in both dementia groups compared to controls, but the orienting effect did not differ between groups. Mean RT in AD was negatively correlated with occipital gray matter (GM) volume and in LBD orienting efficiency was negatively related to occipital white matter (WM) volume. Given that previous studies in less impaired patients suggest a maintenance of the alerting effect, the absent alerting effect in our study suggests a loss of alerting efficiency with dementia progression. While orienting was largely preserved, it might be related to occipital structural abnormalities in LBD. Executive function was markedly impaired in both dementia groups, however, the absence of relations to brain volume suggests that it might be more related to functional rather than macrostructural pathophysiological changes.

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.

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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.

Electroencephalographic derived network differences in Lewy body dementia compared to Alzheimer's disease patients

Dementia with Lewy bodies (DLB) and Alzheimer’s disease (AD) require differential management despite presenting with symptomatic overlap. Currently, there is a need of inexpensive DLB biomarkers which can be fulfilled by electroencephalography (EEG). In this regard, an established electrophysiological difference in DLB is a decrease of dominant frequency (DF)—the frequency with the highest signal power between 4 and 15 Hz. Here, we investigated network connectivity in EEG signals acquired from DLB patients, and whether these networks were able to differentiate DLB from healthy controls (HCs) and associated dementias. We analysed EEG recordings from old adults: HCs, AD, DLB and Parkinson’s disease dementia (PDD) patients. Brain networks were assessed with the minimum spanning tree (MST) within six EEG bands: delta, theta, high-theta, alpha, beta and DF. Patients showed lower alpha band connectivity and lower DF than HCs. DLB and PDD showed a randomised MST compared with HCs and AD in high-theta and alpha but not in DF. The MST randomisation in DLB and PDD reflects decreased brain efficiency as well as impaired neural synchronisation. However, the lack of network topology differences at the DF between all dementia groups and HCs may indicate a compensatory response of the brain to the neuropathology.

The association between cognitive fluctuations and activities of daily living and quality of life among institutionalized patients with dementia

OBJECTIVE

Cognitive fluctuations (CFs) occur commonly in dementia of all types. While it is generally accepted that CFs can affect the clinical rating of dementia severity and neuropsychological performance, little is known about their impact on patients' activities of daily living (ADLs) and quality of life (QOL). Our study aims to explore the impact of CFs on ADLs and QOL among institutionalized patients with dementia.

METHODS

The present study examined the nature and frequency of CFs in 55 institutionalized dementia patients. We used the Dementia Cognitive Fluctuation Scale (DCFS) to assess the presence and severity of CFs. The Alzheimer's Disease Functional Assessment of Change Scale (ADFACS) was used to assess patients' ADLs, and the Quality of Life in Late Stage Dementia scale (QUALID) was used to assess QOL. Linear regression models were used to assess the relationships between CFs, ADLs, and QOL.

RESULTS

The mean age of the patients was 90.41 years (SD = 2.84). Their mean Aggressive Behavior Scale score was 1.13 (SD = 1.59), mean Severe Impairment Battery total score was 86.65 (SD = 13.77), and mean DCFS score was 10.07 (SD = 3.04). The mean ADFACS-ADL score was 10.88 (SD = 6.37), mean ADFACS-IADL score was 16.61 (SD = 9.54), and mean QUALID total score was 18.25 (SD = 5.70). DCFS significantly predicted ADFACS-ADL score (R²  = 0.39, β = 0.30, P = .011) although the relationship between ADFACS-IADL score and DCFS score was not significant (R²  = 0.16, P = .111). DCFS significantly predicted QUALID score (R²  = 0.08, β = 0.29, P = .033).

CONCLUSION

More severe CFs in patients with dementia were significantly associated with impaired ability to engage in ADLs and poorer QOL.