Clinical features of Lewy body dementia: insights into diagnosis and pathophysiology

REM sleep and neurodegeneration

Several brainstem, subcortical and cortical areas are involved in the generation of rapid eye movement (REM) sleep. The alteration of these structures as a result of a neurodegenerative process may therefore lead to REM sleep anomalies. REM sleep behaviour disorder is associated with nightmares, dream-enacting behaviours and increased electromyographic activity in REM sleep. Its isolated form is a harbinger of synucleinopathies such as Parkinson's disease or dementia with Lewy bodies, and neuroprotective interventions are advocated. This link might also be present in patients taking antidepressants, with post-traumatic stress disorder, or with a history of repeated traumatic head injury. REM sleep likely contributes to normal memory processes. Its alteration has also been proposed to be part of the neuropathological changes occurring in Alzheimer's disease.

Managing cognitive impairment in Parkinson's disease: an update of the literature

INTRODUCTION

Cognitive impairment in Parkinson's disease (PD) substantially affects patient outcomes, function, and quality of life. PD-related cognitive dysfunction is often heterogeneous in clinical presentation and rates of progression. As cognitive changes occur in many people with PD, it is essential to evaluate cognition, provide education, and implement management strategies for cognitive symptoms.

AREAS COVERED

This article describes the symptomatology, epidemiology, risk factors, and pathobiology of cognitive impairment in PD. Additionally, the article provides an overview of evidence-based management and other therapeutic and coping strategies for cognitive impairment and dementia in PD. Comment is offered on challenges and opportunities for trials and emerging therapeutics targeting cognitive symptoms or decline.

EXPERT OPINION

While our understanding of cognitive dysfunction in PD has grown, effective and safe therapeutics are still needed to not only treat cognitive impairment and dementia symptomatically but also slow down or prevent cognitive decline. Further research is needed to elucidate the pathobiology of PD cognitive impairment, develop validated biomarkers reflecting cognitive change, and ultimately, integrate clinical and biological frameworks. Consensus regarding cognitive evaluations, definitions, and criteria of cognitive impairment, evaluating functional abilities in the context of cognitive impairment, and determining optimal outcome measures for clinical trials remain unmet needs.

Patients with dementia with Lewy bodies display a signature alteration of their cognitive connectome

Cognition plays a central role in the diagnosis and characterization of dementia with Lewy bodies (DLB). However, the complex associations among cognitive deficits in different domains in DLB are largely unknown. To characterize these associations, we investigated and compared the cognitive connectome of DLB patients, healthy controls (HC), and Alzheimer's disease patients (AD). We obtained data from the National Alzheimer's Coordinating Center. We built cognitive connectomes for DLB (n = 104), HC (n = 3703), and AD (n = 1985) using correlations among 24 cognitive measures mapping multiple cognitive domains. Connectomes were compared using global and nodal graph measures of centrality, integration, and segregation. For global measures, DLB showed a higher global efficiency (integration) and lower transitivity (segregation) than HC and AD. For nodal measures, DLB showed higher global efficiency in most measures, higher participation (centrality) in free-recall memory, processing speed/attention, and executive measures, and lower local efficiency (segregation) than HC. Compared with AD, DLB showed lower nodal strength and local efficiency, especially in memory consolidation. The cognitive connectome of DLB shows a loss of segregation, leading to a loss of cognitive specialization. This study provides the data to advance the understanding of cognitive impairment and clinical phenotype in DLB, with implications for differential diagnosis.

Quantitative proteomic analysis using a mouse model of Lewy body dementia induced by α-synuclein preformed fibrils injection

The aggregation of α-synuclein in the nervous system leads to a class of neurodegenerative disorders termed α-synucleinopathies. A form of primary degenerative dementia called Lewy body dementia (LBD) often develops when these aggregations develop into intracellular inclusions called Lewy bodies (LB) and Lewy neurites (LN). Although high frequency of LBD are the leading cause of dementia after Alzheimer's disease (AD), limited information has been discovered about its pathological pathway or diagnostic criteria. In this report, we attempt to address such shortcomings via utilizing a proteomic approach to identify the proteome changes following intrastriatal injection of α-synuclein pre-formed fibril (α-syn PFF). Using mass spectrometry, we have identified a total of 179 proteins that were either up- or down-regulated at different time points, with the four proteins-TPP3, RAB10, CAMK2A, and DYNLL1, displaying the most significant changes throughout the timeframe. Through further examining the modulated proteins with network-based enrichment analyses, we have found that (1) the most significantly associated neurodegenerative pathways were Parkinson's (pV = 3.0e-16) and Huntington's (pV = 1.9e-15) disease, and (2) the majority of molecular functions specific to the pathology only appeared at later time points. While these results do not expose a conclusive biomarker for LBD, they suggest a framework that is potentially applicable to diagnose and differentiate LBD pathology from other forms of dementia by focusing on the cortical proteome changes which occur in a later time span.

Exploring the Regulatory Landscape of Dementia: Insights from Non-Coding RNAs

Dementia, a multifaceted neurological syndrome characterized by cognitive decline, poses significant challenges to daily functioning. The main causes of dementia, including Alzheimer's disease (AD), frontotemporal dementia (FTD), Lewy body dementia (LBD), and vascular dementia (VD), have different symptoms and etiologies. Genetic regulators, specifically non-coding RNAs (ncRNAs) such as microRNAs (miRNAs), long non-coding RNAs (lncRNAs), and circular RNAs (circRNAs), are known to play important roles in dementia pathogenesis. MiRNAs, small non-coding RNAs, regulate gene expression by binding to the 3' untranslated regions of target messenger RNAs (mRNAs), while lncRNAs and circRNAs act as molecular sponges for miRNAs, thereby regulating gene expression. The emerging concept of competing endogenous RNA (ceRNA) interactions, involving lncRNAs and circRNAs as competitors for miRNA binding, has gained attention as potential biomarkers and therapeutic targets in dementia-related disorders. This review explores the regulatory roles of ncRNAs, particularly miRNAs, and the intricate dynamics of ceRNA interactions, providing insights into dementia pathogenesis and potential therapeutic avenues.

A new perspective on positive symptoms: expression of damage or self-defence mechanism of the brain?

Usually, positive neurological symptoms are considered as the consequence of a mere, afinalistic and abnormal increase in function of specific brain areas. However, according to the Theory of Active Inference, which argues that action and perception constitute a loop that updates expectations according to a Bayesian model, the brain is rather an explorer that formulates hypotheses and tests them to assess the correspondence between internal models and reality. Moreover, the cerebral cortex is characterised by a continuous "conflict" between different brain areas, which constantly attempt to expand in order to acquire more of the limited available computational resources, by means of their dopamine-induced neuroplasticity. Thus, it has recently been suggested that dreams, during rapid eye movement sleep (REMS), protect visual brain areas (deprived of their stimuli during rest) from being conquered by other normally stimulated ones. It is therefore conceivable that positive symptoms also have a functional importance for the brain. We evaluate supporting literature data of a 'defensive' role of positive symptoms and the relevance of dopamine-induced neuroplasticity in the context of neurodegenerative and psychiatric diseases. Furthermore, the possible functional significance of idiopathic REMS-related behavioural disorder as well as phantom limb syndrome is examined. We suggest that positive neurological symptoms are not merely a passive expression of a damage, but active efforts, related to dopamine-induced plasticity, to maintain a correct relationship between the external world and its brain representation, thus preventing healthy cortical areas from ousting injured ones.

Physiological and pathological consequences of exosomes at the blood-brain-barrier interface

Blood-brain barrier (BBB) interface with multicellular structure controls strictly the entry of varied circulating macromolecules from the blood-facing surface into the brain parenchyma. Under several pathological conditions within the central nervous system, the integrity of the BBB interface is disrupted due to the abnormal crosstalk between the cellular constituents and the recruitment of inflammatory cells. Exosomes (Exos) are nano-sized extracellular vesicles with diverse therapeutic outcomes. These particles transfer a plethora of signaling molecules with the potential to modulate target cell behavior in a paracrine manner. Here, in the current review article, the therapeutic properties of Exos and their potential in the alleviation of compromised BBB structure were discussed. Video Abstract.

Orthostatic hypotension in dementia with Lewy bodies: a meta-analysis of prospective studies

PURPOSE

Orthostatic hypotension (OH), one of the supportive clinical features in the diagnosis of dementia with Lewy bodies (DLB), is a significant problem in advanced age because of its severe negative consequences. The aim of this meta-analysis was to investigate the prevalence and risk of OH in patients with DLB.

METHODS

The indexes and databases cited to identify relevant studies were PubMed, ScienceDirect, Cochrane, and Web of Science. The keywords for the search were "Lewy body dementia" and "autonomic dysfunction" or "dysautonomia" or "postural hypotension" or "orthostatic hypotension." English-language articles published from January 1990 to April 2022 were searched. The Newcastle-Ottawa scale was applied to evaluate the quality of the studies. Odds ratios (OR) and risk ratios (RR) were extracted with 95% confidence intervals (CI) and combined using the random effects model after logarithmic transformation. The prevalence in the patients with DLB was also combined using the random effects model.

RESULTS

Eighteen studies (10 case controls and 8 case series) were included to evaluate the prevalence of OH in patients with DLB. Higher rates of OH were found to be associated with DLB (OR 7.71, 95% CI 4.42, 13.44; p < 0.001), and 50.8% of 662 patients had OH.

CONCLUSION

DLB increased the risk of OH by 3.62- to 7.71-fold compared to healthy controls. Therefore, it will be useful to evaluate postural blood pressure changes in the follow-up and treatment of patients with DLB.

GBA1 Gene Mutations in α-Synucleinopathies-Molecular Mechanisms Underlying Pathology and Their Clinical Significance

α-Synucleinopathies comprise a group of neurodegenerative diseases characterized by altered accumulation of a protein called α-synuclein inside neurons and glial cells. This aggregation leads to the formation of intraneuronal inclusions, Lewy bodies, that constitute the hallmark of α-synuclein pathology. The most prevalent α-synucleinopathies are Parkinson's disease (PD), dementia with Lewy bodies (DLB), and multiple system atrophy (MSA). To date, only symptomatic treatment is available for these disorders, hence new approaches to their therapy are needed. It has been observed that GBA1 mutations are one of the most impactful risk factors for developing α-synucleinopathies such as PD and DLB. Mutations in the GBA1 gene, which encodes a lysosomal hydrolase β-glucocerebrosidase (GCase), cause a reduction in GCase activity and impaired α-synuclein metabolism. The most abundant GBA1 gene mutations are N370S or N409S, L444P/L483P and E326K/E365K. The mechanisms by which GCase impacts α-synuclein aggregation are poorly understood and need to be further investigated. Here, we discuss some of the potential interactions between α-synuclein and GCase and show how GBA1 mutations may impact the course of the most prevalent α-synucleinopathies.

Psychosis as a Treatment Target in Dementia: A Roadmap for Designing Interventions

Psychotic phenomena are among the most severe and disruptive symptoms of dementias and appear in 30% to 50% of patients. They are associated with a worse evolution and great suffering to patients and caregivers. Their current treatments obtain limited results and are not free of adverse effects, which are sometimes serious. It is therefore crucial to develop new treatments that can improve this situation. We review available data that could enlighten the future design of clinical trials with psychosis in dementia as main target. Along with an explanation of its prevalence in the common diseases that cause dementia, we present proposals aimed at improving the definition of symptoms and what should be included and excluded in clinical trials. A review of the available information regarding the neurobiological basis of symptoms, in terms of pathology, neuroimaging, and genomics, is provided as a guide towards new therapeutic targets. The correct evaluation of symptoms is transcendental in any therapeutic trial and these aspects are extensively addressed. Finally, a critical overview of existing pharmacological and non-pharmacological treatments is made, revealing the unmet needs, in terms of efficacy and safety. Our work emphasizes the need for better definition and measurement of psychotic symptoms in dementias in order to highlight their differences with symptoms that appear in non-dementing diseases such as schizophrenia. Advances in neurobiology should illuminate the development of new, more effective and safer molecules for which this review can serve as a roadmap in the design of future clinical trials.

Phase 1 Single Ascending and Multiple Ascending Dose Studies of Phosphodiesterase-9 Inhibitor E2027: Confirmation of Target Engagement and Selection of Phase 2 Dose in Dementia With Lewy Bodies Trial

BACKGROUND

E2027 is a novel, highly selective and potent inhibitor of phosphodiesterase9 (PDE9) being evaluated as a treatment for dementia with Lewy bodies.

METHODS

Phase 1, randomized, double-blind, single ascending dose (SAD, n=96) and multiple ascending dose (MAD, n=68) studies evaluated E2027 doses (5 to 1200 mg) in healthy subjects. The impact of age, race (Japanese/non-Japanese), and food on pharmacokinetics (PK)/pharmacodynamics were evaluated. Serial cerebrospinal fluid (CSF) samples were collected to assess the target engagement.

RESULTS

E2027 PK profiles were biphasic (elimination half-life: ~30 hours. Approximately 3-fold accumulation was observed following multiple once-daily dosing. E2027 single doses of 50 to 400 mg resulted in mean maximum increases in CSF cyclic guanosine monophosphate ranging from 293% to 461% within 5.37 to 12.9 hours after dose administration to assess target engagement. Dose-response modelling of steady-state predose CSF cyclic guanosine monophosphate concentrations showed ≥200% increase from baseline is maintained with doses of ≥50 mg QD. The most common adverse events with E2027 were post-LP syndrome and back pain. PK profiles were similar between Japanese and non-Japanese. Higher exposure observed in fed versus fasted state was not considered clinically significant. PK exposure was higher in elderly subjects.

CONCLUSIONS

S.E2027 was well-tolerated following single and multiple administration. E2027 achieved maximal and sustained target engagement at 50 mg QD, the dose selected for the phase 2 clinical trial.

E2027 Cardiac Safety Evaluation With Concentration-Response Modeling of ECG Data to Inform Dose Selection in Studies in Patients With Dementia With Lewy Bodies

BACKGROUND

E2027 is a novel, highly selective and potent inhibitor of phosphodiesterase 9 in development for dementia with Lewy bodies. Cardiac safety assessments for emerging agents are essential to avoid drug-induced QT interval prolongation, which may predispose individuals to potentially fatal ventricular arrhythmias. To evaluate the cardiac safety of E2027 and to inform dose selection for the phase 2 study of E2027 in dementia with Lewy bodies, we evaluated concentration-response modeling of pooled electrocardiogram data.

PATIENTS AND METHODS

A post hoc concentration-QTc analysis evaluated potential QT effects using data from 2 randomized, double-blind studies in healthy subjects: a single ascending dose (SAD) study and a multiple ascending dose (MAD) study. Daily E2027 doses ranged from 5 to 1200 mg.

RESULTS

A linear mixed-effects model was used to establish the relationship between plasma concentrations of E2027 and change from the baseline of QTcF (ΔQTcF). A significant but shallow relationship was observed in the estimated slope of the concentration-ΔQTcF: 0.002 ms/ng/mL (90% confidence interval: 0.0007-0.0031) with a small, nonsignificant treatment effect-specific intercept of -0.6 ms. Based on this pooled concentration-QTc analysis, an effect on the QTcF interval >10 ms can be excluded up to E2027 plasma concentrations of ∼3579 ng/mL, corresponding to a dose at least 4-fold larger than the 50 mg phase 2 dose.

CONCLUSION

This pooled post hoc analysis evaluating cardiac safety of E2027 demonstrated that clinically concerning QTcF prolongation and related cardiac complications are highly unlikely with proposed E2027 doses planned for phase 2.

Robin's Wish and the Complex Causal Web of Death by Suicide

The documentary film Robin's Wish aims to reclaim the media scrutiny around Robin Williams' death, fixating on causation being solely attributed to a postmortem diagnosis of which Williams was unaware-Lewy Body Dementia. The film and other sources as well defined and animated the view that Williams' death by suicide was fully a result of this medical condition, dismissing any possible role for mental disorders. The need to distance from mental disorders can have a palpable undercurrent of stigmatization of them; the documentary missed the opportunity to make its point and simultaneously build allyship with others who have lost someone to suicide who were clearly battling a mental disorder. In this context, we emphasize the importance of looking at causation mediationally (e.g., a neurological condition triggering a major depressive episode culminating, in turn, in death by suicide). Only through encompassing all elements and complexities of the human spirit and condition can we appropriately pay tribute to those we have lost to suicide and simultaneously de-stigmatize mental disorders.

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.

Progression of Clinical Features in Lewy Body Dementia Can Be Detected Over 6 Months

OBJECTIVE

This study aimed to quantify the trajectory and magnitude of change of the key clinical features and corresponding symptom domains of dementia with Lewy bodies (DLB) and Parkinson disease dementia (PDD), including global cognition, parkinsonism, recurrent visual hallucinations, cognitive fluctuations, and sleep disturbance.

METHODS

One hundred sixteen patients with Lewy body dementia (DLB = 72, PDD = 44) underwent assessment at baseline and 3 and 6 months as part of a prospective multicenter randomized controlled trial. Linear mixed models were constructed for core outcome measures using the Mini-Mental State Examination (MMSE), motor section of the Unified Parkinson's Disease Rating Scale (UPDRS-III), Dementia Cognitive Fluctuations Scale (DCFS), and Neuropsychiatric Inventory (NPI).

RESULTS

Within the time frame of our study (6 months), we were able to identify a significant cognitive decline of 1.3 points on the MMSE (p = 0.002) and significant worsening of motor parkinsonism with an increase in UPDRS-III score of 3.2 points (p = 0.018). Fluctuation severity also increased using the DCFS with a 6-month change in score of 1.3 points (p = 0.001). Uniquely, a signal for increased severity of sleep symptoms of 1.2 points (NPI-sleep) was also detectable (p = 0.04). Significant changes in neuropsychiatric symptoms were not detected. There was no difference in rates of change of scores between DLB and PDD.

DISCUSSION

Clinically significant rates of change in core clinical features can be detected and quantified in Lewy body dementia over a relatively short period (6 months) using common clinical instruments and thus may be useful as clinical endpoints for therapeutic trials of disease-modifying and symptomatic agents.

Dementia with Lewy bodies: emerging drug targets and therapeutics

Introduction: Dementia with Lewy bodies (DLB) is characterized by the toxic accumulation of α-synuclein protein inside neural cells; this results in neurodegeneration which is clinically accompanied by behavioral and psychological changes. DLB shares features with Parkinson's disease (PD) and Parkinson's disease dementia (PDD), but also overlaps neurochemically and pathologically with Alzheimer's disease. Symptomatic treatments for LBD differ in their effectiveness while disease-modifying and curative approaches are much needed.Areas covered: We explore emerging therapeutics for DLB through the lens of repurposing approved drugs and survey their potential for disease modifying actions in DLB. Given the complexity of DLB with multiple pathologies, potential therapeutic targets that could affect Lewy body pathology, or metabolism or neurotransmitters or immunomodulation were surveyed. We queried PubMed and ClinicalTrials.gov searches 2017-2020.Expert opinion: DLB is not simply aredux ofAD or PD; hence, treatments should not be exclusively duplicative ofAD or PD directed treatments. This opens amyriad of possibilities for therapeutic approaches that are disease specific or repurposed.

Introduction of an assessment toolkit associated with increased rate of DLB diagnosis

Background

Dementia with Lewy bodies (DLB) and dementia in Parkinson’s disease (PDD) are recognised to be under-recognised in clinical practice in the UK, with only one third to a half of expected cases diagnosed. We aimed to assess whether clinical diagnostic rates could be increased by the introduction of a structured assessment toolkit for clinicians.

Methods

We established baseline diagnostic rates for DLB and PDD in four memory clinics and three movement disorder/Parkinson’s disease (PD) clinics in two separate geographical regions in the UK. An assessment toolkit specifically developed to assist with the recognition and diagnosis of DLB and PDD was then introduced to the same clinical teams and diagnostic rates for DLB and PDD were reassessed.

For assessing DLB diagnosis, a total of 3820 case notes were reviewed before the introduction of the toolkit, and 2061 case notes reviewed after its introduction. For PDD diagnosis, a total of 1797 case notes were reviewed before the introduction of the toolkit and 3405 case notes after it. Mean values and proportions were analysed using Student’s t test for independent samples and χ² test, respectively.

Results

DLB was diagnosed in 4.6% of dementia cases prior to the introduction of the toolkit, and 6.2% of dementia cases afterwards, an absolute rise of 1.6%, equal to a 35% increase in the number of DLB cases diagnosed when using the toolkit (χ² = 4.2, P = 0.041).

The number of PD patients diagnosed with PDD was not found overall to be significantly different when using the toolkit: 9.6% of PD cases before and 8.2% of cases after its introduction (χ² = 1.8, P = 0.18), though the ages of PD patients assessed after the toolkit’s introduction were lower (73.9 years vs 80.0 years, t = 19.2, p < 0.001).

Conclusion

Introduction of the assessment toolkit was associated with a significant increase in the rate of DLB diagnosis, suggesting that a structured means of assessing symptoms and clinical features associated with DLB can assist clinicians in recognising cases. The assessment toolkit did not alter the overall rate of PDD diagnosis, suggesting that alternate means may be required to improve the rate of diagnosis of dementia in Parkinson’s disease.

Altered structural connectivity networks in dementia with lewy bodies

The impairment of large-scale brain networks has been observed in dementia with Lewy bodies (DLB) using functional connectivity, but the potential for an analogous effect on structural covariance patterns has not been determined. Twenty-four probable DLB subjects (mean age 74.3 ± 6.7 years, 16.7% female) and 23 similarly aged Controls were included. All participants underwent 3T MRI imaging with high-resolution T1-weighted magnetization-prepared rapid gradient echo (MPRAGE) sequence. Graph theoretical analyses were performed using variation in regional cortical thickness to construct a structural association matrix with pairwise Pearson correlations. Global and nodal graph parameters were computed to assess between-group differences and community structure was studied in order to quantify large-scale brain networks in both groups. In comparison to Controls, DLB subjects had decreased global efficiency, clustering, modularity and small-worldness of structural networks (all p < 0.05). Nodal measures showed that DLB subjects also had decreased clustering in bilateral temporal regions and decreased closeness centrality in extensive areas including right middle frontal, left cingulate and bilateral occipital lobe (all false-discovery rate (FDR)-corrected q < 0.05). Whereas four distinct modules could be clearly identified in Controls, DLB showed extensively disorganized modules, including default-mode network and dorsal attentional network. Our results suggest a marked impairment in large-scale brain structural networks in DLB, mirroring functional connectivity networks disruption.

Current Concepts and Controversies in the Management of REM Sleep Behavior Disorder

Rapid eye movement (REM) sleep behavior disorder (RBD) is characterized by dream enactment and the loss of muscle atonia during REM sleep, known as REM sleep without atonia (RSWA). RBD can result in significant injuries, prompting patients to seek medical attention. However, in others, it may present only as non-violent behaviors noted as an incidental finding during polysomnography (PSG). RBD typically occurs in the context of synuclein-based neurodegenerative disorders but can also be seen accompanying brain lesions and be exacerbated by medications, particularly antidepressants. There is also an increasing appreciation regarding isolated or idiopathic RBD (iRBD). Symptomatic treatment of RBD is a priority to prevent injurious complications, with usual choices being melatonin or clonazepam. The discovery that iRBD represents a prodromal stage of incurable synucleinopathies has galvanized the research community into delineating the pathophysiology of RBD and defining biomarkers of neurodegeneration that will facilitate future disease-modifying trials in iRBD. Despite many advances, there has been no progress in available symptomatic or neuroprotective therapies for RBD, with recent negative trials highlighting several challenges that need to be addressed to prepare for definitive therapeutic trials for patients with this disorder. These challenges relate to i) the diagnostic and screening strategies applied to RBD, ii) the limited evidence base for symptomatic therapies, (iii) the existence of possible subtypes of RBD, (iv) the relevance of triggering medications, (v) the absence of objective markers of severity, (vi) the optimal design of disease-modifying trials, and vii) the implications around disclosing the risk of future neurodegeneration in otherwise healthy individuals. Here, we review the current concepts in the therapeutics of RBD as it relates to the above challenges and identify pertinent research questions to be addressed by future work.

Genetic Analysis of Chinese Patients with Early-Onset Dementia Using Next-Generation Sequencing

Objective

Early-onset dementia (EOD) is a relatively uncommon form of dementia that afflicts people before age 65. Only a few studies analyzing the genetics of EOD have been performed in the Chinese Han population. Diagnosing EOD remains a challenge due to the diverse genetic and clinical heterogeneity of these diseases. The aim of this study was to investigate the genetic spectrum and clinical features of Chinese patients with EOD.

Materials and Methods

A total of 49 EOD patients were recruited. Targeted next-generation (NGS) analyses were performed to screen for all of the known genes associated with dementia. Possible pathogenic variants were confirmed by performing Sanger sequencing. The genetic spectrum and clinical features of the EOD patients were analyzed.

Results

Seven previously reported pathogenic variants (p.I213T and p.W165C in PSEN1; p.D678N in APP; c.1349_1352del in TBK1; p.P301L and p.R406W in MAPT; p.R110C in NOTCH3) and two novel variants of uncertain significance (p.P436L in PSEN2; c.239-11G>A in TARDBP) were identified.

Conclusion

Our study demonstrated the genetic spectrum and clinical features of EOD patients, and it reveals that genetic testing of known causal genes in EOD patients can help to make a precise diagnosis.