Alzheimer's disease cerebrospinal fluid biomarkers predict cognitive decline in lewy body dementia

Plasma pTau181 Reveals a Pathological Signature that Predicts Cognitive Outcomes in Lewy Body Disease

OBJECTIVE

To determine whether plasma phosphorylated-Tau181 (pTau181) could be used as a diagnostic biomarker of concurrent Alzheimer's disease neuropathologic change (ADNC) or amyloidosis alone, as well as a prognostic, monitoring, and susceptibility/risk biomarker for clinical outcomes in Lewy body disease (LBD).

METHODS

We studied 565 participants: 94 LBD with normal cognition, 83 LBD with abnormal cognition, 114 with Alzheimer's disease, and 274 cognitively normal. Plasma pTau181 levels were measured with the Lumipulse G platform. Diagnostic accuracy for concurrent ADNC and amyloidosis was assessed with Receiver Operating Characteristic curves in a subset of participants with CSF pTau181/Aβ42, and CSF Aβ42/Aβ40 or amyloid-β PET, respectively. Linear mixed effects models were used to examine the associations between baseline and longitudinal plasma pTau181 levels and clinical outcomes.

RESULTS

Plasma pTau181 predicted concurrent ADNC and amyloidosis in LBD with abnormal cognition with 87% and 72% accuracy, respectively. In LBD patients with abnormal cognition, higher baseline plasma pTau181 was associated with worse baseline MoCA and CDR-SB, as well as accelerated decline in CDR-SB. Additionally, in this group, rapid increases in plasma pTau181 over 3 years predicted a faster decline in CDR-SB and memory. In LBD patients with normal cognition, there was no association between baseline or longitudinal plasma pTau181 levels and clinical outcomes; however, elevated pTau181 at baseline increased the risk of conversion to cognitive impairment.

INTERPRETATION

Our findings suggest that plasma pTau181 is a promising biomarker for concurrent ADNC and amyloidosis in LBD. Furthermore, plasma pTau181 holds potential as a prognostic, monitoring, and susceptibility/risk biomarker, predicting disease progression in LBD. ANN NEUROL 2024;96:526-538.

Exploring advancements in early detection of Alzheimer's disease with molecular assays and animal models

Alzheimer's Disease (AD) is a challenging neurodegenerative condition, with overwhelming implications for affected individuals and healthcare systems worldwide. Animal models have played a crucial role in studying AD pathogenesis and testing therapeutic interventions. Remarkably, studies on the genetic factors affecting AD risk, such as APOE and TREM2, have provided valuable insights into disease mechanisms. Early diagnosis has emerged as a crucial factor in effective AD management, as demonstrated by clinical studies emphasizing the benefits of initiating treatment at early stages. Novel diagnostic technologies, including RNA sequencing of microglia, offer promising avenues for early detection and monitoring of AD progression. Therapeutic strategies remain to evolve, with a focus on targeting amyloid beta (Aβ) and tau pathology. Advances in animal models, such as APP-KI mice, and the advancement of anti-Aβ drugs signify progress towards more effective treatments. Therapeutically, the focus has shifted towards intricate approaches targeting multiple pathological pathways simultaneously. Strategies aimed at reducing Aβ plaque accumulation, inhibiting tau hyperphosphorylation, and modulating neuroinflammation are actively being explored, both in preclinical models and clinical trials. While challenges continue in developing validated animal models and translating preclinical findings to clinical success, the continuing efforts in understanding AD at molecular, cellular, and clinical levels offer hope for improved management and eventual prevention of this devastating disease.

In vivo detection of Alzheimer's and Lewy body disease concurrence: Clinical implications and future perspectives

INTRODUCTION

The recent introduction of seed amplification assays (SAAs) detecting misfolded α-synuclein, a pathology-specific marker for Lewy body disease (LBD), has allowed the in vivo identification and phenotypic characterization of patients with co-occurring Alzheimer's disease (AD) and LBD since the early clinical or even preclinical stage.

METHODS

We reviewed studies with an in vivo biomarker-based diagnosis of AD-LBD copathology.

RESULTS

Studies in large cohorts of cognitively impaired individuals have shown that cerebrospinal fluid (CSF) biomarkers detect the coexistence of AD and LB pathology in approximately 20%-25% of them, independently of the primary clinical diagnosis. Compared to those with pure AD, AD-LBD patients showed worse global cognition, especially in attentive/executive and visuospatial functions, and worse motor functions. In cognitively unimpaired individuals, concurrent AD-LBD pathologies predicted longitudinal cognitive progression with faster worsening of global cognition, memory, and attentive/executive functions.

DISCUSSION

Future research studies aiming for a better precision medicine approach should develop SAAs further to reach a quantitative evaluation or staging of each underlying pathology using a single biofluid sample.

HIGHLIGHTS

α-Synuclein seed amplification assays (SAAs) provide a specific marker for Lewy body disease (LBD). SAAs allow for the in vivo identification of co-occurring LBD in patients with Alzheimer's disease (AD). AD-LBD coexist in 20-25% of cognitively impaired elderly individuals, and ∼8% of those asymptomatic. Compared to pure AD, AD-LBD causes a faster worsening of cognitive functions. AD-LBD is associated with worse attentive/executive, memory, visuospatial and motor functions.

Differentiating Prodromal Dementia with Lewy Bodies from Prodromal Alzheimer's Disease: A Pragmatic Review for Clinicians

This pragmatic review synthesises the current understanding of prodromal dementia with Lewy bodies (pDLB) and prodromal Alzheimer's disease (pAD), including clinical presentations, neuropsychological profiles, neuropsychiatric symptoms, biomarkers, and indications for disease management. The core clinical features of dementia with Lewy bodies (DLB)-parkinsonism, complex visual hallucinations, cognitive fluctuations, and REM sleep behaviour disorder are common prodromal symptoms. Supportive clinical features of pDLB include severe neuroleptic sensitivity, as well as autonomic and neuropsychiatric symptoms. The neuropsychological profile in mild cognitive impairment attributable to Lewy body pathology (MCI-LB) tends to include impairment in visuospatial skills and executive functioning, distinguishing it from MCI due to AD, which typically presents with impairment in memory. pDLB may present with cognitive impairment, psychiatric symptoms, and/or recurrent episodes of delirium, indicating that it is not necessarily synonymous with MCI-LB. Imaging, fluid and other biomarkers may play a crucial role in differentiating pDLB from pAD. The current MCI-LB criteria recognise low dopamine transporter uptake using positron emission tomography or single photon emission computed tomography (SPECT), loss of REM atonia on polysomnography, and sympathetic cardiac denervation using meta-iodobenzylguanidine SPECT as indicative biomarkers with slowing of dominant frequency on EEG among others as supportive biomarkers. This review also highlights the emergence of fluid and skin-based biomarkers. There is little research evidence for the treatment of pDLB, but pharmacological and non-pharmacological treatments for DLB may be discussed with patients. Non-pharmacological interventions such as diet, exercise, and cognitive stimulation may provide benefit, while evaluation and management of contributing factors like medications and sleep disturbances are vital. There is a need to expand research across diverse patient populations to address existing disparities in clinical trial participation. In conclusion, an early and accurate diagnosis of pDLB or pAD presents an opportunity for tailored interventions, improved healthcare outcomes, and enhanced quality of life for patients and care partners.

Multiple biomarkers improve diagnostic accuracy across Lewy body and Alzheimer's disease spectra

OBJECTIVE

More than half of neurodegenerative disease patients have multiple pathologies at autopsy; however, most receive one diagnosis during life. We used the α-synuclein seed amplification assay (αSyn-SAA) and CSF biomarkers for amyloidosis and Alzheimer's disease (AD) neuropathological change (ADNC) to determine the frequency of co-pathologies in participants clinically diagnosed with Lewy body (LB) disease or AD.

METHODS

Using receiver operating characteristic analyses on retrospective CSF samples from 150 participants determined αSyn-SAA accuracy, sensitivity, and specificity for identifying clinically defined LB disease and predicting future change in clinical diagnosis. CSF biomarkers helped determine the frequency of concomitant Lewy body pathology, ADNC, and/or amyloidosis in participants with LB disease and AD, across clinical spectra.

RESULTS

Following a decade-long follow-up, the clinically or autopsy-defined diagnosis changed for nine participants. αSyn-SAA demonstrated improved accuracy (91.3%), sensitivity (89.3%), and specificity (93.3%) for identifying LB disease compared to all non-LB disease, highlighting the limitations of clinical diagnosis alone. When examining biomarkers of co-pathology, amyloidosis was present in 18%, 48%, and 71% (χ2(2) = 13.56, p = 0.001) and AD biomarkers were present in 0%, 8.7%, and 42.9% (χ2(2) = 18.44, p < 0.001) of LB disease participants with different stages of cognitive impairment respectively. Co-occurring biomarkers for αSyn-SAA and amyloidosis were present in 12% and 14% of AD compared to 43% and 57% LB disease participants with different stages of cognitive impairment (χ2(3) = 13.87, p = 0.003).

INTERPRETATION

Our study shows that using a combination of αSyn-SAA and AD biomarkers can identify people with αSyn, ADNC, and co-pathology better and earlier than traditional clinical diagnostic criteria alone.

Cerebrospinal fluid glial fibrillary acidic protein, in contrast to amyloid beta protein, is associated with disease symptoms in Huntington's disease

INTRODUCTION

Huntington's disease (HD) is a hereditary neurodegenerative disease, currently lacking disease-modifying treatments. Biomarkers are needed for objective assessment of disease progression. Evidence supports both complex protein aggregation and astrocyte activation in HD. This study assesses the 42 amino acid long amyloid beta (Aβ42) and glial fibrillary acidic protein (GFAP) as potential biomarkers in the cerebrospinal fluid (CSF) of HD mutation carriers.

METHODS

CSF from participants was obtained from three sites in Sweden. Clinical symptoms were graded with the composite Unified Huntington's disease rating scale (cUHDRS). Protein concentrations were measured using ELISA. Pearson correlations were calculated to assess disease progression association. Results were adjusted for age and collection site.

RESULTS

The study enrolled 28 manifest HD patients (ManHD), 13 premanifest HD gene-expansion carriers (PreHD) and 20 controls. Aβ42 levels did not differ between groups and there was no correlation with measures of disease progression. GFAP concentration was higher in ManHD (424 ng/l, SD 253) compared with both PreHD (266 ng/l, SD 92.4) and controls (208 ng/l, SD 83.7). GFAP correlated with both cUHDRS (r = -0.77, p < 0.001), and 5-year risk of disease onset (r = 0.70, p = 0.008).

CONCLUSION

We provide evidence that indicates CSF Aβ42 has limited potential as a biomarker for HD. GFAP is a potential biomarker of progression in HD. Validation in larger cohorts measuring GFAP in blood and CSF would be of interest.

Cerebrospinal-fluid biomarkers for predicting phenoconversion in patients with isolated rapid-eye movement sleep behavior disorder

STUDY OBJECTIVES

Patients with isolated rapid-eye-movement sleep behavior disorder (iRBD) have an increased risk of developing neurodegenerative diseases. This study assessed cerebrospinal-fluid (CSF) biomarkers of neurodegeneration and blood-brain barrier (BBB) alteration in patients with iRBD compared to controls and ascertain whether these biomarkers may predict phenoconversion to alpha-synucleinopathies (Parkinson's Disease (PD), Dementia with Lewy bodies (DLB), Multiple System Atrophy (MSA)).

METHODS

Patients and controls underwent between 2012 and 2016 a neurological assessment, a lumbar puncture for CSF biomarker analysis (β-amyloid42 - Aβ42; total-tau, and phosphorylated tau), and BBB alteration (CSF/serum albumin ratio). All patients with iRBD were followed until 2021 and then classified into patients who converted to alpha-synucleinopathies (iRBD converters, cRBD) or not (iRBD non-converters, ncRBD).

RESULTS

Thirty-four patients with iRBD (mean age 67.12 ± 8.14) and 33 controls (mean age 64.97 ± 8.91) were included. At follow-up (7.63 ± 3.40 years), eight patients were ncRBD and 33 patients were cRBD: eleven converted to PD, 10 to DLB, and two to MSA. Patients with iRBD showed lower CSF Aβ42 levels and higher CSF/serum albumin ratio than controls. Cox regression analysis showed that the phenoconversion rate increases with higher motor impairment (hazard ratio [HR] = 1.23, p = 0.032). CSF Aβ42 levels predicted phenoconversion to DLB (HR = 0.67, p = 0.038) and BBB alteration predicted phenoconversion to PD (HR = 1.20, p = 0.038).

DISCUSSION

This study showed that low CSF Aβ42 levels and high BBB alteration may predict the phenoconversion to DLB and PD in patients with iRBD, respectively. These findings highlight the possibility to discriminate phenoconversion in iRBD patients through CSF biomarkers; however, further studies are needed.

ATN cerebrospinal fluid biomarkers in dementia with Lewy bodies: Initial results from the United States Dementia with Lewy Bodies Consortium

INTRODUCTION

The National Institute on Aging - Alzheimer's Association (NIA-AA) ATN research framework proposes to use biomarkers for amyloid (A), tau (T), and neurodegeneration (N) to stage individuals with AD pathological features and track changes longitudinally. The overall aim was to utilize this framework to characterize pre-mortem ATN status longitudinally in a clinically diagnosed cohort of dementia with Lewy bodies (DLB) and to correlate it with the post mortem diagnosis.

METHODS

The cohort was subtyped by cerebrospinal fluid (CSF) ATN category. A subcohort had longitudinal data, and a subgroup was neuropathologically evaluated.

RESULTS

We observed a significant difference in Aβ42/40 after 12 months in the A+T- group. Post mortem neuropathologic analyses indicated that most of the p-Tau 181 positive (T+) cases also had a high Braak stage.

DISCUSSION

This suggests that DLB patients who are A+ but T- may need to be monitored to determine whether they remain A+ or ever progress to T positivity.

HIGHLIGHTS

Some A+T- DLB subjects transition from A+ to negative after 12-months. Clinically diagnosed DLB with LBP-AD (A+T+) maintain their positivity. Clinically diagnosed DLB with LBP-AD (A+T+) maintain their positivity. Monitoring of the A+T- sub-type of DLB may be necessary.

Neuropathological correlates of neuropsychiatric symptoms in dementia

INTRODUCTION

Neuropsychiatric symptoms (NPS) are common in Lewy body disease (LBD), but their etiology is poorly understood.

METHODS

In a population-based post mortem study neuropathological data was collected for Lewy body (LB) neuropathology, neurofibrillary tangles (NFT), amyloid beta burden, TDP-43, lacunar infarcts, cerebral amyloid angiopathy (CAA), and hyaline atherosclerosis. Post mortem interviews collected systematic information regarding NPS and cognitive status. A total of 1038 cases were included: no pathology (NP; n = 761), Alzheimer's disease (AD; n = 189), LBD (n = 60), and AD+LBD (n = 28).

RESULTS

Hallucinations were associated with higher LB Braak stages, while higher NFT Braak staging was associated with depression, agitation, and greater number of symptoms in the Neuropsychiatric Inventory. Cases with dual AD+LBD pathology had the highest risk of hallucinations, agitation, apathy, and total symptoms but a multiplicative interaction between these pathologies was not significant.

DISCUSSION

LB and AD pathology contribute differentially to NPS likely with an additive process contributing to the increased burden of NPS.

Cognitive Impairment in Neurodegenerative Movement Disorders

Patients with neurodegenerative movement disorders can develop cognitive impairment during the disease. Cognitive symptoms have been associated with decreased quality of life, higher caregiver burden, and earlier institutionalization, and are therefore critical for physicians to understand and address. The evaluation of cognitive performance of patients with neurodegenerative movement disorders is important for providing adequate diagnosis, management, prognosis, and support patients and their caregivers. In this review, we discuss the features of the cognitive impairment profile of commonly encountered movement disorders: Parkinson's disease, dementia with Lewy bodies, multiple system atrophy, progressive supranuclear palsy, corticobasal syndrome, and Huntington's disease. In addition, we provide neurologists with practical guidance and evaluation tools for the assessment and management of these challenging patients.

Biomarkers of diagnosis, prognosis, pathogenesis, response to therapy: Convergence or divergence? Lessons from Alzheimer's disease and synucleinopathies

Alzheimer's disease (AD) is the most common disorder associated with cognitive impairment. Recent observations emphasize the pathogenic role of multiple factors inside and outside the central nervous system, supporting the notion that AD is a syndrome of many etiologies rather than a "heterogeneous" but ultimately unifying disease entity. Moreover, the defining pathology of amyloid and tau coexists with many others, such as α-synuclein, TDP-43, and others, as a rule, not an exception. Thus, an effort to shift our AD paradigm as an amyloidopathy must be reconsidered. Along with amyloid accumulation in its insoluble state, β-amyloid is becoming depleted in its soluble, normal states, as a result of biological, toxic, and infectious triggers, requiring a shift from convergence to divergence in our approach to neurodegeneration. These aspects are reflected-in vivo-by biomarkers, which have become increasingly strategic in dementia. Similarly, synucleinopathies are primarily characterized by abnormal deposition of misfolded α-synuclein in neurons and glial cells and, in the process, depleting the levels of the normal, soluble α-synuclein that the brain needs for many physiological functions. The soluble to insoluble conversion also affects other normal brain proteins, such as TDP-43 and tau, accumulating in their insoluble states in both AD and dementia with Lewy bodies (DLB). The two diseases have been distinguished by the differential burden and distribution of insoluble proteins, with neocortical phosphorylated tau deposition more typical of AD and neocortical α-synuclein deposition peculiar to DLB. We propose a reappraisal of the diagnostic approach to cognitive impairment from convergence (based on clinicopathologic criteria) to divergence (based on what differs across individuals affected) as a necessary step for the launch of precision medicine.

Sex differences in dementia with Lewy bodies: Focused review of available evidence and future directions

In this review, we summarize the current knowledge on sex differences in dementia with Lewy bodies (DLB) relating to epidemiology, clinical features, neuropathology, biomarkers, disease progression, and caregiving. While many studies show a higher DLB prevalence in men, this finding is inconsistent and varies by study approach. Visual hallucinations may be more common and occur earlier in women with DLB, whereas REM sleep behavior disorder may be more common and occur earlier in men. Several studies report a higher frequency of parkinsonism in men with DLB, while the frequency of fluctuations appears similar between sexes. Women tend to be older, have greater cognitive impairment at their initial visit, and are delayed in meeting DLB criteria compared to men. Women are also more likely to have Lewy body disease with co-existing AD-related pathology than so-called "pure" Lewy body disease, while men may present with either. Research is mixed regarding the impact of sex on DLB progression. Biomarker and treatment research assessing for sex differences is lacking. Women provide the majority of caregiving in DLB but how this affects the caregiving experience is uncertain. Gaining a better understanding of sex differences will be instrumental in aiding future development of sex-specific strategies in DLB for early diagnosis, care, and drug development.

The effect of antidepressant therapy on a patient with progressive supranuclear palsy accompanied by depression, anxiety and fluctuating dementia

Progressive supranuclear palsy (PSP) is a complex clinicopathologic disease which can only be definitively confirmed at autopsy. It belongs to a family of conditions exhibiting Parkinson's syndrome, including Lewy body dementia (LBD) or dementia with Lewy body (DLB), and Parkinson's disease dementia (PDD). In regards to clinical manifestations, these two dementias have many overlapping characteristics. The declines of cognition in older patients of dementia are generally accompanied by depression, anxiety, hallucinations, delusions, eating and sleep disorders. This can lead to the difficulty in distinguishing the types of dementia and accurately diagnosing the disease. Herein, we present a complex case of PSP with depression, anxiety, and fluctuating dementia in which DLB was initially suspected. Before antidepressant therapy, the patient showed extrapyramidal symptoms as well as major depression, which lead to greatly impaired movement. Moreover, this patient was an older person with depression disorders, implicating further complexities of late life depression. After two weeks of therapy with antidepressants, the patient had reduced depressive symptoms, and even the somatic symptoms were improved. This case demonstrated that antidepressant therapy can be effective in improving emotion and cognition among patients with late life depression.

Dementia with Lewy bodies: Impact of co-pathologies and implications for clinical trial design

Dementia with Lewy bodies (DLB) is clinically defined by the presence of visual hallucinations, fluctuations, rapid eye movement (REM) sleep behavioral disorder, and parkinsonism. Neuropathologically, it is characterized by the presence of Lewy pathology. However, neuropathological studies have demonstrated the high prevalence of coexistent Alzheimer's disease, TAR DNA-binding protein 43 (TDP-43), and cerebrovascular pathologic cases. Due to their high prevalence and clinical impact on DLB individuals, clinical trials should account for these co-pathologies in their design and selection and the interpretation of biomarkers values and outcomes. Here we discuss the frequency of the different co-pathologies in DLB and their cross-sectional and longitudinal clinical impact. We then evaluate the utility and possible applications of disease-specific and disease-nonspecific biomarkers and how co-pathologies can impact these biomarkers. We propose a framework for integrating multi-modal biomarker fingerprints and step-wise selection and assessment of DLB individuals for clinical trials, monitoring target engagement, and interpreting outcomes in the setting of co-pathologies.

Disease progression in dementia with Lewy bodies: A longitudinal study on clinical symptoms, quality of life and functional impairment

BACKGROUND AND OBJECTIVES

Dementia with Lewy Bodies (DLB) is a heterogeneous disease, with variable signs and symptoms across multiple domains. We aimed to identify associations with rate of change in cognition, everyday functioning (IADL) and quality of life (QoL).

METHODS

We included 121 DLB patients (69 ± 6 yrs, 14%F, MMSE: 25 ± 3) in our prospective cohort (follow-up 2 ± 1 yrs). We described progression of symptoms and cognitive decline over time. Mixed models were used to investigate whether changes in symptoms were associated to changes in IADL (FAQ), QoL (QoL-AD) and caregiver burden (ZBI). Last, we investigated whether baseline symptoms and biomarkers predicted decline in cognition (MMSE), IADL (FAQ) and QoL (QoL-AD).

RESULTS

Parkinsonism and RBD were most frequently present early in the disease course, while hallucinations were more likely to develop in a later stage. MMSE (annual change β ± SE = -2.06 ± 0.23), QoL-AD (-1.03 ± 0.20), and FAQ (3.04 ± 0.30) declined over time. Increasing severity of clinical symptoms was associated to increases in FAQ, QoL-AD and caregiver burden. Baseline clinical symptoms were not predictive for decline in these outcomes. By contrast, AD co-pathology (CSF pTau/Aβ42 ratio) was associated to steeper decline in MMSE (-1.23 ± 0.54). Medial temporal atrophy (-0.81 ± 0.26) and global cortical atrophy (-0.73 ± 0.36) predisposed for decline in QoL-AD.

CONCLUSIONS

Our findings imply that underlying disease processes, rather than clinical symptomatology aid in predicting decline. These findings are relevant for treatment strategies and the development of DLB specific outcome measures.

Joint Modeling Study Identifies Blood-Based Transcripts Link to Cognitive Decline in Parkinson's Disease

BACKGROUND

Cognitive decline in Parkinson's disease (PD) is prevalent, insidious, and burdensome during the progression of the disease.

OBJECTIVES

We aimed to find transcriptome-wide biomarkers in blood to predict cognitive decline and identify patients at high risk with cognitive impairment in PD.

METHODS

We carried out joint modeling analysis to characterize transcriptome-wide longitudinal gene expression and its association with the progression of mild cognitive impairment (MCI) in PD patients. The average time-dependent area under the curves (AUCs) were used for evaluating the accuracy of the significant joint models. A cognitive survival score (CogSs) derived from joint model was leveraged to predict the occurrence of MCI. All predicting models were built in a discovery cohort with 272 patients and replicated in an independent cohort with 177 patients.

RESULTS

We identified five longitudinal varied expression of transcripts that were significantly associated with MCI progression in patients with PD. The most significant transcript IGLC1 joint model accurately predicted the progression of MCI in PD patients in the discovery and replication cohorts (average time-dependent AUCs >0.82). The CogSs derived from the optimal IGLC1 joint model had a high accuracy at early study stage in both cohorts (AUC ≥0.91).

CONCLUSIONS

Our transcriptome-wide joint modeling analysis uncovered five blood-based transcripts related to cognitive decline in PD. The joint models will serve as a useful resource for clinicians and researchers to screen PD patients with high risk of development of cognitive impairment and pave the path for Parkinson's personalized medicine. © 2022 International Parkinson and Movement Disorder Society.

Comparison of brain microstructure alterations on diffusion kurtosis imaging among Alzheimer’s disease, mild cognitive impairment, and cognitively normal individuals

Objective

Our study aimed to explore the differences in brain microstructure in patients with Alzheimer’s disease (AD) and with mild cognitive impairment (MCI) and in individuals with normal cognition using diffusion kurtosis imaging (DKI) to identify a potential non-invasive biomarker of AD.

Materials and methods

A total of 61 subjects were included in our study, including 20 subjects diagnosed with AD, 21 patients diagnosed with amnestic MCI, and 20 cognitively normal individuals. We acquired magnetic resonance imaging (MRI) scans, and DKI images were processed. Twelve regions of interest were drawn, and various parameters were measured and analyzed using SPSS version 11.0 software.

Results

Comparative analysis showed that differences in brain regions in terms of mean diffusion (MD) and mean kurtosis (MK) between groups were the most marked. Precuneus MD, temporal MK, precuneus MK, and hippocampal MK were significantly correlated with neuropsychological test scores. Hippocampal MK showed the strongest correlation with the medial temporal lobe atrophy score (r = −0.510), and precuneus MD had the strongest correlation with the Koedam score (r = 0.463). The receiver operating curve analysis revealed that hippocampal MK exhibited better diagnostic efficacy than precuneus MD for comparisons between any group pair.

Conclusion

DKI is capable of detecting differences in brain microstructure between patients with AD, patients with MCI, and cognitively normal individuals. Moreover, it compensates for the deficiencies of conventional MRI in detecting pathological changes in microstructure before the appearance of macroscopic atrophy. Hippocampus MK was the most sensitive single parameter map for differentiating patients with AD, patients with MCI, and cognitively normal individuals.

The relationship between plasma biomarkers and amyloid PET in dementia with Lewy bodies

INTRODUCTION

Amyloid-β (Aβ) deposition is common in dementia with Lewy bodies (DLB) and has been associated with more rapid disease progression. An effective biomarker that identified the presence of significant brain Aβ in people with DLB may be useful to identify and stratify participants for research studies and to inform prognosis in clinical practice. Plasma biomarkers are emerging as candidates to fulfil this role.

METHODS

Thirty-two participants with DLB had brain amyloid (18F-florbetapir) PET, of whom 27 also had an MRI to enable the calculation of 18F-florbetapir SUVR. Plasma Aβ42/40, phosphorylated tau (p-tau181), glial fibrillary acidic protein (GFAP) and neurofilament light (NfL) were measured using single molecule array (Simoa). The plasma biomarkers were investigated for correlation with 18F-florbetapir SUVR, discriminant ability to identify Aβ-positive cases based on a predefined SUVR threshold of 1.10 and correlation with subsequent cognitive decline over one year.

RESULTS

All four plasma markers significantly correlated with 18F-florbetapir SUVR (|β| = 0.40-0.49; p < .05). NfL had the greatest area under the receiver operating characteristic curve to identify Aβ-positive cases (AUROC 0.84 (95% CI 0.66, 1); β = 0.46, p = .001), whereas Aβ42/40 had the smallest (AUROC 0.73 (95% CI 0.52, 0.95); β = -0.47, p = .01). Accuracy was highest when combining all four biomarkers (AUROC 0.92 (95% CI 0.80, 1)). Lower plasma Aβ42/40 was significantly associated with more rapid decline in cognition (β = 0.53, p < .01).

CONCLUSIONS

Plasma biomarkers have the potential to identify Aβ deposition in DLB. Further work in other cohorts is required to determine and validate optimal cut-offs for these biomarkers.

Classical Cerebrospinal Fluid Biomarkers in Dementia with Lewy Bodies

The use and interpretation of diagnostic cerebrospinal fluid (CSF) biomarkers for neurodegenerative disorders, such as Dementia with Lewy bodies (DLB), represent a clinical challenge. According to the literature, the composition of CSF in DLB patients varies. Some patients present with reduced levels of amyloid, others with full Alzheimer Disease CSF profile (both reduced amyloid and increased phospho-tau) and some with a normal profile. Some patients may present with abnormal levels of a-synuclein. Continuous efforts will be required to establish useful CSF biomarkers for the early diagnosis of DLB. Given the heterogeneity of methods and results between studies, further validation is fundamental before conclusions can be drawn.

A Comparison of Cerebrospinal Fluid Beta-Amyloid and Tau in Idiopathic Normal Pressure Hydrocephalus and Neurodegenerative Dementias

Purpose

Idiopathic normal pressure hydrocephalus (iNPH) is the leading reversible cause of cognitive impairment and gait disturbance that has similar clinical manifestations and accompanies to major neurodegenerative disorders in older adults. We aimed to investigate whether cerebrospinal fluid (CSF) biomarker for Alzheimer’s disease (AD) may be useful in the differential diagnosis of iNPH.

Patients and Methods

Amyloid-beta (Aß) 42 and 40, total tau (t-tau), phosphorylated tau (p-tau) were measured via ELISA in 192 consecutive CSF samples of patients with iNPH (n=80), AD (n=48), frontotemporal dementia (FTD) (n=34), Lewy body diseases (LBDs) (n=30) consisting of Parkinson’s disease dementia and dementia with Lewy bodies.

Results

The mean age of the study population was 75.6±7.7 years, and 54.2% were female. CSF Aβ₄₂ levels were significantly higher, and p-tau and t-tau levels were lower in iNPH patients than in those with AD and LBDs patients. Additionally, iNPH patients had significantly higher levels of t-tau than those with FTD. Age and sex-adjusted multi-nominal regression analysis revealed that the odds of having AD relative to iNPH decreased by 37% when the Aβ₄₂ level increased by one standard deviation (SD), and the odds of having LBDs relative to iNPH decreased by 47%. The odds of having LBDs relative to iNPH increased 76% when the p-tau level increased 1SD. It is 2.5 times more likely for a patient to have LBD relative to NPH and 2.1 times more likely to have AD relative to iNPH when the t-tau value increased 1SD.

Conclusion

Our results suggest that levels of CSF Aβ₄₂, p-tau, and t-tau, in particularly decreased t-tau, are of potential value in differentiating iNPH from LBDs and also confirm previous studies reporting t-tau level is lower and Aβ₄₂ level is higher in iNPH than in AD.

A Longitudinal Study of Plasma pTau181 in Mild Cognitive Impairment with Lewy Bodies and Alzheimer's Disease

BACKGROUND

Alzheimer's disease (AD) co-pathology is common in dementia with Lewy bodies and is associated with increased decline. Plasma pTau181 is a blood-based biomarker that can detect AD co-pathology.

OBJECTIVES

We investigated whether pTau181 was associated with cognitive decline in mild cognitive impairment with Lewy bodies (MCI-LB) and MCI with AD (MCI-AD).

METHODS

We assessed plasma pTau181 using a single-molecule array (Simoa) immunoassay at baseline and follow-up in a longitudinal cohort of MCI-LB, MCI-AD, and controls.

RESULTS

One hundred forty-six subjects (56 probable MCI-LB, 22 possible MCI-LB, 44 MCI-AD, and 24 controls) were reviewed for up to 5.7 years. Probable MCI-LB had significantly higher pTau181 (22.2% mean increase) compared with controls and significantly lower (24.4% mean decrease) levels compared with MCI-AD. Receiver operating characteristic analyses of pTau181 in discriminating probable MCI-LB from controls showed an area under the curve (AUC) of 0.68 (83% specificity, 57% sensitivity); for discriminating MCI-AD from healthy controls, AUC was 0.8 (83.3% specificity, 72.7% sensitivity). pTau181 concentration was less useful in discriminating between probable MCI-LB and MCI-AD: AUC of 0.64 (71.4% specificity, 52.3% sensitivity). There was an association between pTau181 and cognitive decline in MCI-AD but not in MCI-LB. In a subset with repeat samples there was a nonsignificant 3% increase per follow-up year in plasma pTau181. The rate of change in pTau181 was not significantly different in different diagnostic subgroups.

CONCLUSIONS

pTau181 was not associated with an increased decline assessed using either baseline or repeat pTau181. pTau181 partially discriminated probable MCI-LB from controls and MCI-AD from controls but was not useful in distinguishing probable MCI-LB from MCI-AD.

Fluid and Tissue Biomarkers of Lewy Body Dementia: Report of an LBDA Symposium

The Lewy Body Dementia Association (LBDA) held a virtual event, the LBDA Biofluid/Tissue Biomarker Symposium, on January 25, 2021, to present advances in biomarkers for Lewy body dementia (LBD), which includes dementia with Lewy bodies (DLBs) and Parkinson's disease dementia (PDD). The meeting featured eight internationally known scientists from Europe and the United States and attracted over 200 scientists and physicians from academic centers, the National Institutes of Health, and the pharmaceutical industry. Methods for confirming and quantifying the presence of Lewy body and Alzheimer's pathology and novel biomarkers were discussed.

Association of the ATN Research Framework With Clinical Profile, Ccognitive Decline, and Mortality in Patients With Dementia With Lewy Bodies

BACKGROUND AND OBJECTIVES

The ATN framework has been developed to categorize biological processes within the Alzheimer's disease (AD) continuum. Since AD pathology often coincides with dementia with Lewy Bodies (DLB), we aimed to investigate the distribution of ATN profiles in DLB and associate ATN-profiles in DLB to prognosis.

METHODS

We included 202 DLB patients from the Amsterdam Dementia Cohort (68±7yrs, 19%F, MMSE: 24±3, DAT-SPECT abnormal: 105/119). Patients were classified into eight profiles according to the ATN framework, using CSF Aβ₄₂ (A), CSF p-tau (T) and medial temporal atrophy scores (N). We compared presence of clinical symptoms in ATN profiles and used linear mixed models to analyze decline on cognitive tests (follow-up 3±2yrs for n=139). Mortality risk was assessed using Cox proportional hazards analysis. Analyses were performed on both the eight profiles, as well as three clustered categories (normal AD biomarkers, non-AD pathologic change, AD continuum).

RESULTS

Fifty (25%) DLB patients had normal AD biomarkers (A-T-N-), 37 (18%) had non-AD pathologic change (A-T+N-: 10%/A-T-N+: 6%/A-T+N+: 3%) and 115 (57%) were classified within the AD continuum (A+T-N-: 20%/A+T+N-: 16%/A+T-N+: 10%/A+T+N+: 9%). A+T+N+ patients were older and least often had RBD symptoms. Parkinsonism was more often present in A+T-, compared to A-T+ (independent of N). Compared to patients with normal AD biomarkers, patients in A+ categories showed steeper decline on memory tests and higher mortality risk. Cognitive decline and mortality did not differ between non-AD pathologic change and normal AD biomarkers.

DISCUSSION

In our DLB cohort, we found clinically relevant associations between ATN categories and disease manifestation. Patients within the AD continuum had steeper cognitive decline and shorter survival. Implementing the ATN framework within DLB patients aids in subtyping patients based on underlying biological processes and could provide targets for future treatment strategies, e.g. AD modifying treatment. Expanding the framework by incorporating markers for alpha-synucleinopathy would improve the use of the framework to characterize dementia patients with mixed pathology, which could enhance proper stratification of patients for therapeutic trials.

Parsing heterogeneity within dementia with Lewy bodies using clustering of biological, clinical, and demographic data

BACKGROUND

Dementia with Lewy bodies (DLB) includes various core clinical features that result in different phenotypes. In addition, Alzheimer's disease (AD) and cerebrovascular pathologies are common in DLB. All this increases the heterogeneity within DLB and hampers clinical diagnosis. We addressed this heterogeneity by investigating subgroups of patients with similar biological, clinical, and demographic features.

METHODS

We studied 107 extensively phenotyped DLB patients from the European DLB consortium. Factorial analysis of mixed data (FAMD) was used to identify dimensions in the data, based on sex, age, years of education, disease duration, Mini-Mental State Examination (MMSE), cerebrospinal fluid (CSF) levels of AD biomarkers, core features of DLB, and regional brain atrophy. Subsequently, hierarchical clustering analysis was used to subgroup individuals based on the FAMD dimensions.

RESULTS

We identified 3 dimensions using FAMD that explained 38% of the variance. Subsequent hierarchical clustering identified 4 clusters. Cluster 1 was characterized by amyloid-β and cerebrovascular pathologies, medial temporal atrophy, and cognitive fluctuations. Cluster 2 had posterior atrophy and showed the lowest frequency of visual hallucinations and cognitive fluctuations and the worst cognitive performance. Cluster 3 had the highest frequency of tau pathology, showed posterior atrophy, and had a low frequency of parkinsonism. Cluster 4 had virtually normal AD biomarkers, the least regional brain atrophy and cerebrovascular pathology, and the highest MMSE scores.

CONCLUSIONS

This study demonstrates that there are subgroups of DLB patients with different biological, clinical, and demographic characteristics. These findings may have implications in the diagnosis and prognosis of DLB, as well as in the treatment response in clinical trials.

Advances in dementia with Lewy bodies

Dementia with Lewy bodies (DLB) is a clinical diagnosis representing a specific presentation of a pathological α-synucleinopathy (Lewy body disease). DLB is one entity under the broader term Lewy body dementia, which also includes Parkinson’s disease dementia. Recent advances in DLB include publication of updated diagnostic criteria and recognition of prodromal DLB states, including mild cognitive impairment, delirium-onset, and psychiatric-onset forms. Research criteria for the mild cognitive impairment form of DLB were published in 2020. Increasing research shows that concomitant Alzheimer’s disease pathology in individuals with DLB is common in addition to the α-synucleinopathy pathology. This has implications for biomarker use and expected progression. Identifying biomarkers for DLB is an area of active research. Cerebrospinal fluid and skin biopsy tests are now commercially available in the United States, but their role in routine clinical care is not yet established. Additional research and biomarkers are needed. Research suggests that median survival after DLB diagnosis is 3–4 years, but there are rapidly and slowly progressive forms. Most individuals with DLB die of complications of the disease. Clinical trials for individuals with DLB have increased over the last 5 years, targeting both symptoms and underlying pathology. Effective therapies remain an unmet need, however. This review focuses on recent advances with an emphasis on literature that informs clinical care.

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.

Dementia with Lewy bodies research consortia: A global perspective from the ISTAART Lewy Body Dementias Professional Interest Area working group

Dementia with Lewy bodies (DLB) research has seen a significant growth in international collaboration over the last three decades. However, researchers face a challenge in identifying large and diverse samples capable of powering longitudinal studies and clinical trials. The DLB research community has begun to focus efforts on supporting the development and harmonization of consortia, while also continuing to forge networks within which data and findings can be shared. This article describes the current state of DLB research collaborations on each continent. We discuss several established DLB cohorts, many of whom have adopted a common framework, and identify emerging collaborative initiatives that hold the potential to expand DLB networks and diversify research cohorts. Our findings identify geographical areas into which the global DLB networks should seek to expand, and we propose strategies, such as the creation of data-sharing platforms and the harmonization of protocols, which may further potentiate international collaboration.

Plasma Neurofilament Light Chain Predicts Cognitive Progression in Prodromal and Clinical Dementia with Lewy Bodies

Plasma neurofilament light chain (NfL) is a marker of neuronal damage in different neurological disorders and might predict disease progression in dementia with Lewy bodies (DLB). The study enrolled 45 controls and 44 DLB patients (including 17 prodromal cases) who underwent an extensive assessment at baseline and at 2 years follow-up. At baseline, plasma NfL levels were higher in both probable DLB and prodromal cases compared to controls. Plasma NfL emerged as the best predictor of cognitive decline compared to age, sex, and baseline severity variables. The study supports the role of plasma NfL as a useful prognostic biomarker from the early stages of DLB.

Association of cerebral microbleeds with cerebrospinal fluid Alzheimer-biomarkers and clinical symptoms in early dementia with Lewy bodies

OBJECTIVES

To determine the prevalence, localization and associations of cerebral microbleeds (CMB) in dementia with Lewy bodies (DLB) with its core clinical symptoms and cerebrospinal fluid (CSF) biomarkers of Alzheimer's disease (AD). We hypothesize DLB patients with CMB have increased amyloid burden compared to those without CMB, which could also translate into clinical differences.

METHODS

Retrospective cross-sectional analysis from the AlphaLewyMA study (https://clinicaltrials.gov/ct2/show/NCT01876459). Patients underwent a standardized protocol of brain MRI including 3D T1, 3D FLAIR and T2* sequences, and CSF analysis of AD biomarkers. CMB and white matter hyperintensities (WMHs) were visually assessed in prodromal and mild demented (DLB, N = 91) and AD (AD, N = 67) patients.

RESULTS

CMB prevalence did not differ among DLB and AD (24.2% vs. 37.3%; p = 0.081). CMB were mainly distributed in lobar topographies in both DLB (74%) and AD (89%). CMB in DLB was not associated with global cognitive performance, executive functioning, speed of information processing, or AD CSF biomarkers. Similarly, there was no difference regarding specific clinical symptoms: fluctuations, psychotic phenomena, sleep behavior disorder and Parkinsonism between DLB patients with and without CMB. AD patients with CMB had increased burden of WMH compared to those without (2.1 ± 0.86 vs. 1.4 ± 0.89; p = 0.005), according to Fazekas scale, whereas no significant difference was observed in DLB patients (1.68 ± 0.95 vs. 1.42 ± 0.91; p = 0.25).

CONCLUSION

CMB were equally prevalent with similar topographic distribution in both DLB and AD patients. CMB was not associated with CSF AD biomarkers or core clinical symptoms in DLB.

Greater Variability in Cognitive Decline in Lewy Body Dementia Compared to Alzheimer's Disease

Studies indicate more rapid cognitive decline in patients with Lewy body dementia (LBD) compared to Alzheimer's disease (AD). However, there has been less focus on any difference in the variability of cognitive decline. We assessed Mini-Mental State Examination (MMSE) test performance at baseline and annually for 5 years in 222 patients with mild dementia in the DemVest study who had either AD (137) or LBD (85). We used linear mixed models (LMMs) with random intercepts (variability in MMSE at baseline) and slopes (variability in MMSE decline), with years in study, age, gender, and diagnosis as independent variables. A non-linear (quadratic) trajectory was selected, interacting with age and diagnosis. To study differences in variance, we compared a regular LMM (i.e., a homoscedastic model), which assumes equal variance across groups, to a heteroscedastic model, assuming unequal intercept and slope variance based on diagnosis. The heteroscedastic model gave a better fit (Likelihood ratio test: χ2 = 30.3, p < 0.001), showing overall more variability in LBD. Further, the differences in intercept and slope variances were tested using a modified Wald test. The MMSE intercept variance (AD: 2.78, LBD: 7.75, difference: 4.97, p = 0.021) and slope variance (AD: 2.62, LBD 7.81, difference: 5.19, p = 0.004) were both higher in LBD. In conclusion, patients with LBD in the DemVest study have a higher variability in MMSE scores at study inclusion, and in MMSE decline compared to AD. Accordingly, clinical trials on LBD may need a larger sample size compared to AD.

Dissecting Sex-Related Cognition between Alzheimer's Disease and Diabetes: From Molecular Mechanisms to Potential Therapeutic Strategies

The brain is a sexually dimorphic organ that implies different functions and structures depending on sex. Current pharmacological approaches against different neurological diseases act distinctly in male and female brains. In all neurodegenerative diseases, including Alzheimer's disease (AD), sex-related outcomes regarding pathogenesis, prevalence, and response to treatments indicate that sex differences are important for precise diagnosis and therapeutic strategy. Pathogenesis of AD includes vascular dementia, and in most cases, this is accompanied by metabolic complications with similar features as those assembled in diabetes. This review discusses how AD-associated dementia and diabetes affect cognition in relation to sex difference, as both diseases share similar pathological mechanisms. We highlight potential protective strategies to mitigate amyloid-beta (Aβ) pathogenesis, emphasizing how these drugs act in the male and female brains.

α-Synuclein Heteromers in Red Blood Cells of Alzheimer's Disease and Lewy Body Dementia Patients

BACKGROUND

Red blood cells (RBCs) contain the majority of α-synuclein (α-syn) in blood, representing an interesting model for studying the peripheral pathological alterations proved in neurodegeneration.

OBJECTIVE

The current study aimed to investigate the diagnostic value of total α-syn, amyloid-β (Aβ1-42), tau, and their heteroaggregates in RBCs of Lewy body dementia (LBD) and Alzheimer's disease (AD) patients compared to healthy controls (HC).

METHODS

By the use of enzyme-linked immunosorbent assays, RBCs concentrations of total α-syn, Aβ1-42, tau, and their heteroaggregates (α-syn/Aβ1-42 and α-syn/tau) were measured in 27 individuals with LBD (Parkinson's disease dementia, n = 17; dementia with Lewy bodies, n = 10), 51 individuals with AD (AD dementia, n = 37; prodromal AD, n = 14), and HC (n = 60).

RESULTS

The total α-syn and tau concentrations as well as α-syn/tau heterodimers were significantly lower in the LBD group and the AD group compared with HC, whereas α-syn/Aβ1-42 concentrations were significantly lower in the AD dementia group only. RBC α-syn/tau heterodimers had a higher diagnostic accuracy for differentiating patients with LBD versus HC (AUROC = 0.80).

CONCLUSION

RBC α-syn heteromers may be useful for differentiating between neurodegenerative dementias (LBD and AD) and HC. In particular, RBC α-syn/tau heterodimers have demonstrated good diagnostic accuracy for differentiating LBD from HC. However, they are not consistently different between LBD and AD. Our findings also suggest that α-syn, Aβ1-42, and tau interact in vivo to promote the aggregation and accumulation of each other.

A/T/(N) Profile in Cerebrospinal Fluid of Parkinson's Disease with/without Cognitive Impairment and Dementia with Lewy Bodies

Neuropathological investigations report that in synucleinopathies with dementia, namely Parkinson's disease (PD) with dementia (PDD) and dementia with Lewy bodies (DLB), the histopathological hallmarks of Alzheimer's Disease (AD), in particular amyloid plaques, are frequently observed. In this study, we investigated the cerebrospinal fluid (CSF) AD biomarkers in different clinical phenotypes of synucleinopathies. CSF Aβ42/Aβ40 ratio, phosphorylated tau and total tau were measured as markers of amyloidosis (A), tauopathy (T) and neurodegeneration (N) respectively, in 98 PD (48 with mild cognitive impairment, PD-MCI; 50 cognitively unimpaired, PD-nMCI), 14 PDD and 15 DLB patients, and 48 neurological controls (CTRL). In our study, CSF AD biomarkers did not significantly differ between CTRL, PD-MCI and PD-nMCI patients. In PD-nMCI and PD-MCI groups, A-/T-/N- profile was the most represented. Prevalence of A+ was similar in PD-nMCI and PD-MCI (10% and 13%, respectively), being higher in PDD (64%) and in DLB (73%). DLB showed the lowest values of Aβ42/Aβ40 ratio. Higher total tau at baseline predicted a worse neuropsychological outcome after one year in PD-MCI. A+/T+, i.e., AD-like CSF profile, was most frequent in the DLB group (40% vs. 29% in PDD).

Genealogy of the neurodegenerative diseases based on a meta-analysis of age-stratified incidence data

While the central common feature of the neurodegenerative diseases (NDs) is the accumulation of misfolded proteins, they share other pathogenic mechanisms. However, we miss an explanation for the onset of the NDs. The mechanisms through which genetic mutations, present from conception are expressed only after several decades of life are unknown. We aim to find clues on the complexity of the disease onset trigger of the different NDs expressed in the number of steps of factors related to a disease. We collected brain autopsies on diseased patients with NDs, and found a dynamic increase of the ND multimorbidity with the advance of age. Together with the observation that the NDs accumulate multiple misfolded proteins, and the same misfolded proteins are involved in more than one ND, motivated us to propose a model for a genealogical tree of the NDs. To collect the dynamic data needed to build the tree, we used a Big-data approach that searched automatically epidemiological datasets for age-stratified incidence of NDs. Based on meta-analysis of over 400 datasets, we developed an algorithm that checks whether a ND follows a multistep model, finds the number of steps necessary for the onset of each ND, finds the number of common steps with other NDs and the number of specific steps of each ND, and builds with these findings a parsimony tree of the genealogy of the NDs. The tree discloses three types of NDs: the stem NDs with less than 3 steps; the trunk NDs with 5 to 6 steps; and the crown NDs with more than 7 steps. The tree provides a comprehensive understanding of the relationship across the different NDs, as well as a mathematical framework for dynamic adjustment of the genealogical tree of the NDs with the appearance of new epidemiological studies and the addition of new NDs to the model, thus setting the basis for the search for the identity and order of these steps. Understanding the complexity, or number of steps, of factors related to disease onset trigger is important prior deciding to study single factors for a multiple steps disease.

β-Amyloid and tau biomarkers and clinical phenotype in dementia with Lewy bodies

OBJECTIVE

In a multicenter cohort of probable dementia with Lewy bodies (DLB), we tested the hypothesis that β-amyloid and tau biomarker positivity increases with age, which is modified by APOE genotype and sex, and that there are isolated and synergistic associations with the clinical phenotype.

METHODS

We included 417 patients with DLB (age 45-93 years, 31% women). Positivity on β-amyloid (A+) and tau (T+) biomarkers was determined by CSF β-amyloid_1-42 and phosphorylated tau in the European cohort and by Pittsburgh compound B and AV-1451 PET in the Mayo Clinic cohort. Patients were stratified into 4 groups: A-T-, A+T-, A-T+, and A+T+.

RESULTS

A-T- was the largest group (39%), followed by A+T- (32%), A+T+ (15%), and A-T+ (13%). The percentage of A-T- decreased with age, and A+ and T+ increased with age in both women and men. A+ increased more in APOE ε4 carriers with age than in noncarriers. A+ was the main predictor of lower cognitive performance when considered together with T+. T+ was associated with a lower frequency of parkinsonism and probable REM sleep behavior disorder. There were no significant interactions between A+ and T+ in relation to the clinical phenotype.

CONCLUSIONS

Alzheimer disease pathologic changes are common in DLB and are associated with the clinical phenotype. β-Amyloid is associated with cognitive impairment, and tau pathology is associated with lower frequency of clinical features of DLB. These findings have important implications for diagnosis, prognosis, and disease monitoring, as well as for clinical trials targeting disease-specific proteins in DLB.

CLASSIFICATION OF EVIDENCE

This study provides Class II evidence that in patients with probable DLB, β-amyloid is associated with lower cognitive performance and tau pathology is associated with lower frequency of clinical features of DLB.

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.

The combined effect of amyloid-β and tau biomarkers on brain atrophy in dementia with Lewy bodies

BACKGROUND

Alzheimer's disease (AD)-related pathology is frequently found in patients with dementia with Lewy bodies (DLB). However, it is unknown how amyloid-β and tau-related pathologies influence neurodegeneration in DLB. Understanding the mechanisms underlying brain atrophy in DLB can improve our knowledge about disease progression, differential diagnosis, drug development and testing of anti-amyloid and anti-tau therapies in DLB.

OBJECTIVES

We aimed at investigating the combined effect of CSF amyloid-β42, phosphorylated tau and total tau on regional brain atrophy in DLB in the European DLB (E-DLB) cohort.

METHODS

86 probable DLB patients from the E-DLB cohort with CSF and MRI data were included. Random forest was used to analyze the association of CSF biomarkers (predictors) with visual rating scales for medial temporal lobe atrophy (MTA), posterior atrophy (PA) and global cortical atrophy scale-frontal subscale (GCA-F) (outcomes), including age, sex, education and disease duration as extra predictors.

RESULTS

DLB patients with abnormal MTA scores had abnormal CSF Aβ42, shorter disease duration and older age. DLB patients with abnormal PA scores had abnormal levels of CSF Aβ42 and p-tau, older age, lower education and shorter disease duration. Abnormal GCA-F scores were associated with lower education, male sex, and older age, but not with any AD-related CSF biomarker.

CONCLUSIONS

This study shows preliminary data on the potential combined effect of amyloid-β and tau-related pathologies on the integrity of posterior brain cortices in DLB patients, whereas only amyloid-β seems to be related to MTA. Future availability of α-synuclein biomarkers will help us to understand the effect of α-synuclein and AD-related pathologies on brain integrity in DLB.

PLCG2 protective variant p.P522R modulates tau pathology and disease progression in patients with mild cognitive impairment

A rare coding variant (rs72824905, p.P522R) conferring protection against Alzheimer's disease (AD) was identified in the gene encoding the enzyme phospholipase-C-γ2 (PLCG2) that is highly expressed in microglia. To explore the protective nature of this variant, we employed latent process linear mixed models to examine the association of p.P522R with longitudinal cognitive decline in 3595 MCI patients, and in 10,097 individuals from population-based studies. Furthermore, association with CSF levels of pTau181, total tau, and Aβ1-42 was assessed in 1261 MCI patients. We found that MCI patients who carried the p.P522R variant showed a slower rate of cognitive decline compared to non-carriers and that this effect was mediated by lower pTau181 levels in CSF. The effect size of the association of p.P522R with the cognitive decline and pTau181 was similar to that of APOE-ε4, the strongest genetic risk factor for AD. Interestingly, the protective effect of p.P522R was more pronounced in MCI patients with low Aβ1-42 levels suggesting a role of PLCG2 in the response to amyloid pathology. In line with this hypothesis, we observed no protective effect of the PLCG2 variant on the cognitive decline in population-based studies probably due to the lower prevalence of amyloid positivity in these samples compared to MCI patients. Concerning the potential biological underpinnings, we identified a network of co-expressed proteins connecting PLCG2 to APOE and TREM2 using unsupervised co-regulatory network analysis. The network was highly enriched for the complement cascade and genes differentially expressed in disease-associated microglia. Our data show that p.P522R in PLCG2 reduces AD disease progression by mitigating tau pathology in the presence of amyloid pathology and, as a consequence, maintains cognitive function. Targeting the enzyme PLCG2 might provide a new therapeutic approach for treating AD.

Cerebrospinal fluid markers analysis in the differential diagnosis of dementia with Lewy bodies and Parkinson's disease dementia

Dementia with Lewy bodies (DLB) and Parkinson's disease dementia (PDD) share a couple of clinical similarities that is often a source of diagnostic pitfalls. We evaluated the discriminatory potential of brain-derived CSF markers [tau, p-tau (181P), Aβ_1-42, NSE and S100B] across the spectrum of Lewy body disorders and assessed whether particular markers are associated with cognitive status in investigated patients. The tau CSF level, amyloid β_1-42 and p-tau/tau ratio were helpful in the distinction between DLB and PDD (p = 0.04, p = 0.002 and p = 0.02, respectively) as well as from PD patients (p < 0.001, p = 0.001 and p = 0.002, respectively). Furthermore, the p-tau/tau ratio enabled the differentiation of DLB with mild dementia from PDD patients (p = 0.02). The CSF tau and p-tau levels in DLB and CSF tau and p-tau/tau ratio in PDD patients reflected the severity of dementia. Rapid disease course was associated with the decrease of Aβ_1-42 in DLB but not in PDD. Elevation of S100B in DLB (p < 0.0001) as well as in PDD patients (p = 0.002) in comparison to controls was estimated. Hence, with the appropriate clinical context; the CSF marker profile could be helpful in distinguishing DLB from PDD patients even in early stages of dementia.

Amyloid Imaging and Longitudinal Clinical Progression in Dementia With Lewy Bodies

OBJECTIVE

Significant amyloid deposition is present in approximately half of all cases of dementia with Lewy bodies (DLB). We sought to determine whether amyloid deposition was associated with more rapid clinical decline over 1 year.

METHODS

Twenty-eight participants had a baseline clinical assessment and amyloid PET scan, followed by a further clinical assessment after 1 year. Changes in clinical measures were compared with amyloid deposition assessed by visual rating and cortical standardized uptake value ratio.

RESULTS

Amyloid deposition on visual rating was associated with greater decline in Mini-Mental State Examination and daily function over 1 year. There was no correlation between cortical standardized uptake value ratio and clinical measures.

CONCLUSIONS

This study provides further evidence for a link between amyloid deposition and clinical progression in DLB. Pathologies such as amyloid, and their interaction with α-synuclein, remain possible treatment targets in DLB.

Sex-specific associations with cerebrospinal fluid biomarkers in dementia with Lewy bodies

Background

Dementia with Lewy bodies (DLB) is more prevalent in men than in women. In addition, post-mortem studies found sex differences in underlying pathology. It remains unclear whether these differences are also present antemortem in in vivo biomarkers, and whether sex differences translate to variability in clinical manifestation. The objective of this study was to evaluate sex differences in cerebrospinal fluid (CSF) biomarker concentrations (i.e., alpha-synuclein (α-syn), amyloid β1-42 (Aβ42), total tau (Tau), phosphorylated tau at threonine 181 (pTau)) and clinical characteristics in DLB.

Methods

We included 223 DLB patients from the Amsterdam Dementia Cohort, of which 39 were women (17%, age 70 ± 6, MMSE 21 ± 6) and 184 men (83%, age 68 ± 7, MMSE 23 ± 4). Sex differences in CSF biomarker concentrations (i.e., α-syn, Aβ42, Tau, and pTau) were evaluated using age-corrected general linear models (GLM). In addition, we analyzed sex differences in core clinical features (i.e., visual hallucinations, parkinsonism, cognitive fluctuations, and REM sleep behavior disorder (RBD) and cognitive test scores using age- and education-adjusted GLM.

Results

Women had lower CSF α-syn levels (F 1429 ± 164 vs M 1831 ± 60, p = 0.02) and CSF Aβ42 levels (F 712 ± 39 vs M 821 ± 18, p = 0.01) compared to men. There were no sex differences for (p) Tau concentrations (p > 0.05). Clinically, women were older, had a shorter duration of complaints (F 2 ± 1 vs M 4 ± 3, p < 0.001), more frequent hallucinations (58% vs 38%, p = 0.02), and scored lower on MMSE and a fluency task (MMSE, p = 0.02; animal fluency, p = 0.006). Men and women did not differ on fluctuations, RBD, parkinsonism, or other cognitive tests.

Conclusions

Women had lower Aβ42 and α-syn levels than men, alongside a shorter duration of complaints. Moreover, at the time of diagnosis, women had lower cognitive test scores and more frequent hallucinations. Based on our findings, one could hypothesize that women have a more aggressive disease course in DLB compared to men. Future research should investigate whether women and men with DLB might benefit from sex-specific treatment strategies.

The path to biomarker-based diagnostic criteria for the spectrum of neurodegenerative diseases

Introduction: The postmortem examination still represents the reference standard for detecting the pathological nature of chronic neurodegenerative diseases (NDD). This approach displays intrinsic conceptual limitations since NDD represent a dynamic spectrum of partially overlapping phenotypes, shared pathomechanistic alterations that often give rise to mixed pathologies.Areas covered: We scrutinized the international clinical diagnostic criteria of NDD and the literature to provide a roadmap toward a biomarker-based classification of the NDD spectrum. A few pathophysiological biomarkers have been established for NDD. These are time-consuming, invasive, and not suitable for preclinical detection. Candidate screening biomarkers are gaining momentum. Blood neurofilament light-chain represents a robust first-line tool to detect neurodegeneration tout court and serum progranulin helps detect genetic frontotemporal dementia. Ultrasensitive assays and retinal scans may identify Aβ pathology early, in blood and the eye, respectively. Ultrasound also represents a minimally invasive option to investigate the substantia nigra. Protein misfolding amplification assays may accurately detect α-synuclein in biofluids.Expert opinion: Data-driven strategies using quantitative rather than categorical variables may be more reliable for quantification of contributions from pathophysiological mechanisms and their spatial-temporal evolution. A systems biology approach is suitable to untangle the dynamics triggering loss of proteostasis, driving neurodegeneration and clinical evolution.

Molecular profiling in Parkinsonian syndromes: CSF biomarkers

An accurate and early diagnosis of degenerative parkinsonian syndromes is a major need for their correct and timely therapeutic management. The current diagnostic criteria are mostly based on clinical features and molecular imaging. However, diagnostic doubts often persist especially in the early stages of diseases when signs are slight, ambiguous and overlapping among different syndromes. Molecular imaging may not be altered in the early stages of diseases, also failing to discriminate among different syndromes. Cerebrospinal fluid (CSF) represents an ideal source of biomarkers reflecting different pathways of neuropathological changes taking place in the brain and preceding the clinical onset. The aim of this review is to provide un update on CSF biomarkers in parkinsonian disorders, discussing in detail their association with neuropathological correlates. Their potential contribution in differential diagnosis and prognostic assessment of different parkinsonian syndromes is also discussed. Before entering the clinical use both for diagnostic and prognostic purposes, these CSF biomarkers need to be thoroughly assessed in terms of pre-analytical and analytical variability, as well as to clinical validation in independent cohorts.

In vivo Prevalence of Alzheimer Biomarkers in Dementia with Lewy Bodies

BACKGROUND

Neuropathological studies indicate concomitant Alzheimer's disease (AD) pathology in patients with dementia with Lewy bodies (DLB).

OBJECTIVES

To measure cerebrospinal fluid (CSF) levels of β-amyloid peptide with 42 amino acids (Aβ42), total tau protein (τT), and tau phosphorylated at threonine 181 (τP-181) in 38 patients fulfilling the diagnostic criteria of probable DLB according to the most recent (4th consensus) report.

METHODS

Double-sandwich commercial ELISAs (Innotest; Fujirebio, Gent, Belgium) were used for measurements.

RESULTS

According to the current cutoff values of our laboratory, 4 biomarker profiles were noted: abnormal levels of Aβ42 only (44.7%), full AD profile (39.5%), abnormal levels of τT only (5.3%), and normal levels of all 3 biomarkers (10.5%). AD profile was associated with female sex, older age, lower education, and lower MMSE scores.

CONCLUSIONS

Reduction in Αβ42 in DLB may be more common (>80% of patients) than previously thought, and ∼40% may have the typical CSF AD biomarker profile. AD biochemistry in DLB may be an evolving process showing increasing frequency with disease progression.

Components of the choline oxidation pathway modify the association between the apolipoprotein ε4 gene variant and cognitive decline in patients with dementia

BACKGROUND

Metabolites involved in one-carbon metabolism (OCM) may predict cognitive prognosis in dementia. The link between OCM, apolipoprotein E (APOE), and DNA methylation creates a biologically plausible mechanism of interaction.

AIM

To assess OCM metabolites as predictors of 5-year cognitive prognosis in patients with mild dementia, and in subgroups defined by the APOEε4 allele variant.

METHODS

We followed one-hundred and fifty-two patients with mild dementia (86 with Alzheimer's disease, 66 with Lewy body dementia, including 90 with at least one APOEε4 allele) for 5 years with annual Mini-Mental State Examinations (MMSE). Total homocysteine, methionine, choline, betaine, dimethylglycine, sarcosine, folate, cobalamin and pyridoxal 5'-phoshate were measured in serum at baseline. We used linear mixed models to assess metabolite-MMSE associations, including 3-way interactions between metabolites, time, and APOEε4. False-discovery rate adjusted p-values (Q-values) are reported.

RESULTS

Metabolite concentrations were not different in patients with dementia according to the presence of APOEε4. Overall, serum concentration of total homocysteine was inversely associated with MMSE performance, while betaine was positively associated with MMSE (Q < 0.05), but neither was associated with MMSE decline. Serum concentrations of betaine, dimethylglycine and sarcosine, however, were associated with slower MMSE decline in patients with APOEε4, but with faster MMSE decline in patients without the allele (all 3-way interactions: Q < 0.05).

CONCLUSION

Components of the choline oxidation pathway are associated with a better cognitive prognosis in APOEε4 carriers and a worse cognitive prognosis in non-carriers. Further research investigating targeted metabolic interventions according to APOE allele status is warranted.