Dementia with Lewy bodies

Neuropsychological Assessment for Early Detection and Diagnosis of Dementia: Current Knowledge and New Insights

Dementia remains an underdiagnosed syndrome, and there is a need to improve the early detection of cognitive decline. This narrative review examines the role of neuropsychological assessment in the characterization of cognitive changes associated with dementia syndrome at different states. The first section describes the early indicators of cognitive decline and the major barriers to their identification. Further, the optimal cognitive screening conditions and the most widely accepted tests are described. The second section analyzes the main differences in cognitive performance between Alzheimer's disease and other subtypes of dementia. Finally, the current challenges of neuropsychological assessment in aging/dementia and future approaches are discussed. Essentially, we find that current research is beginning to uncover early cognitive changes that precede dementia, while continuing to improve and refine the differential diagnosis of neurodegenerative disorders that cause dementia. However, neuropsychology faces several barriers, including the cultural diversity of the populations, a limited implementation in public health systems, and the adaptation to technological advances. Nowadays, neuropsychological assessment plays a fundamental role in characterizing cognitive decline in the different stages of dementia, but more efforts are needed to develop harmonized procedures that facilitate its use in different clinical contexts and research protocols.

Decoding Neurodegeneration: A Comprehensive Review of Molecular Mechanisms, Genetic Influences, and Therapeutic Innovations

Neurodegenerative disorders often acquire due to genetic predispositions and genomic alterations after exposure to multiple risk factors. The most commonly found pathologies are variations of dementia, such as frontotemporal dementia and Lewy body dementia, as well as rare subtypes of cerebral and cerebellar atrophy-based syndromes. In an emerging era of biomedical advances, molecular-cellular studies offer an essential avenue for a thorough recognition of the underlying mechanisms and their possible implications in the patient's symptomatology. This comprehensive review is focused on deciphering molecular mechanisms and the implications regarding those pathologies' clinical advancement and provides an analytical overview of genetic mutations in the case of neurodegenerative disorders. With the help of well-developed modern genetic investigations, these clinically complex disturbances are highly understood nowadays, being an important step in establishing molecularly targeted therapies and implementing those approaches in the physician's practice.

Expression Levels of an Alpha-Synuclein Transcript in Blood May Distinguish between Early Dementia with Lewy Bodies and Parkinson's Disease

Lewy body diseases (LBD) including dementia with Lewy bodies (DLB) and Parkinson disease (PD) are characterized by alpha-synuclein pathology. DLB is difficult to diagnose and peripheral biomarkers are urgently needed. Therefore, we analyzed the expression of five alpha-synuclein gene (SNCA) transcripts, SNCAtv1, SNCAtv2, SNCAtv3, SNCA126, and SNCA112, in 45 LBD and control temporal cortex samples and in the blood of 72 DLB, 59 PD, and 54 control subjects. The results revealed overexpression of SNCAtv1 and SNCA112 in DLB, and SNCAtv2 in PD temporal cortices. In DLB blood, diminution of all SNCA transcripts was observed. SNCAtv1 and SNCAtv2 were diminished in PD with disease onset before 70 years. SNCAtv3, driven by its own promoter, showed opposite expression in early DLB and PD, suggesting that its amount may be an early, DLB specific biomarker. Correlation between blood transcript levels and disease duration was positive in DLB and negative in PD, possibly reflecting differences in brain alpha-synuclein aggregation rates associated with differences in disease courses. In conclusion, SNCA transcripts showed a disease-specific increase in the brain and were diminished in blood of LBD patients. SNCAtv3 expression was decreased in early DLB and increased in early PD and could be a biomarker for early DLB diagnosis.

Treatment Options for Dementia with Lewy Bodies: A Network Meta-Analysis of Randomised Control Trials

INTRODUCTION

Dementia with Lewy bodies (DLB) is the third most common type of dementia after Alzheimer's disease (AD) and vascular dementia. Treatment is targeted at specific disease manifestations/symptoms. While donepezil is approved for the treatment of DLB in Japan, to date no other treatment has been approved for this indication anywhere in the world. Notwithstanding, many of the medications that are approved for AD are widely used in the treatment of DLB with varying degrees of success. Consequently, clinical evidence is limited, and there is a need to understand the comparative efficacy and safety of currently used therapies for DLB. The aim of this study was to conduct a network meta-analysis (NMA) to evaluate the outcomes of the available treatment options based on currently used trial endpoints.

METHODS

Using data from a previously published systematic review, we conducted an NMA to investigate the efficacy and safety of treatments in patients with DLB. Networks were based on change from baseline of efficacy endpoints (Mini-Mental State Examination; Neuropsychiatric Inventory; Unified Parkinson's Disease Rating Scale) and rate of safety events (overall adverse events [AEs]; discontinuations; discontinuations due to AEs; psychiatric events).

RESULTS

Focused around a common treatment option of placebo, the NMA comprised studies on donepezil, rivastigmine, memantine and quetiapine. Donepezil 3 mg, 5 mg and 10 mg doses were compared against each other and placebo. Overall, donepezil consistently performed better than the alternative treatments when compared to placebo for all efficacy and safety endpoints. However, the small sample size and/or heterogeneity of the studies led to uncertainty, resulting in no statistically significant differences favouring any treatment above another or placebo.

CONCLUSION

Despite the lack of statistical significance, when assessing the efficacy and safety outcomes for each drug in the evidence network, donepezil appeared to have a more favourable overall benefit/risk profile for patients with DLB. Further comparative trials are required to improve understanding of the true difference between existing and potential future treatment options.

Cholinergic Modulation of Glial Function During Aging and Chronic Neuroinflammation

Aging is a complex biological process that increases the risk of age-related cognitive degenerative diseases such as dementia, including Alzheimer’s disease (AD), Lewy Body Dementia (LBD), and mild cognitive impairment (MCI). Even non-pathological aging of the brain can involve chronic oxidative and inflammatory stress, which disrupts the communication and balance between the brain and the immune system. There has been an increasingly strong connection found between chronic neuroinflammation and impaired memory, especially in AD. While microglia and astrocytes, the resident immune cells of the central nervous system (CNS), exerting beneficial effects during the acute inflammatory phase, during chronic neuroinflammation they can become more detrimental. Central cholinergic circuits are involved in maintaining normal cognitive function and regulating signaling within the entire cerebral cortex. While neuronal-glial cholinergic signaling is anti-inflammatory and anti-oxidative, central cholinergic neuronal degeneration is implicated in impaired learning, memory sleep regulation, and attention. Although there is evidence of cholinergic involvement in memory, fewer studies have linked the cholinergic anti-inflammatory and anti-oxidant pathways to memory processes during development, normal aging, and disease states. This review will summarize the current knowledge of cholinergic effects on microglia and astroglia, and their role in both anti-inflammatory and anti-oxidant mechanisms, concerning normal aging and chronic neuroinflammation. We provided details on how stimulation of α7 nicotinic acetylcholine (α7nACh) receptors can be neuroprotective by increasing amyloid-β phagocytosis, decreasing inflammation and reducing oxidative stress by promoting the nuclear factor erythroid 2-related factor 2 (Nrf2) pathways and decreasing the release of pro-inflammatory cytokines. There is also evidence for astroglial α7nACh receptor stimulation mediating anti-inflammatory and antioxidant effects by inhibiting the nuclear factor-κB (NF-κB) pathway and activating the Nrf2 pathway respectively. We conclude that targeting cholinergic glial interactions between neurons and glial cells via α7nACh receptors could regulate neuroinflammation and oxidative stress, relevant to the treatment of several neurodegenerative diseases.

Use of Cholinesterase Inhibitors in Non-Alzheimer's Dementias

Non-Alzheimer's dementias constitute 30% of all dementias and present with major cognitive and behavioral disturbances. Cholinesterase inhibitors improve memory by increasing brain acetylcholine levels and are approved symptomatic therapies for Alzheimer's disease (AD). They have also been investigated in other types of dementias with potential cholinergic dysfunction. There is compelling evidence for a profound cholinergic deficit in Lewy Body dementia (LBD) and Parkinson's disease dementia (PDD), even to a greater extent than AD. However, this deficit is difficult to objectivize in vascular dementia (VaD) given the increased comorbidity with AD. Furthermore, there is minimal to no evidence for cholinergic loss in frontotemporal dementia (FTD). Although cholinesterase inhibitors showed significant improvement in cognitive, behavioral, and functional measures in both LBD and PDD clinical trials, only rivastigmine is approved for PDD, due to the heterogeneity of the scales used, the duration of trials, and the limited sample sizes impacting data interpretation. Similarly, the interpretation of findings in VaD trials are limited by the lack of pre-defined inclusion criteria for 'pure VaD' and the wide heterogeneity of patients enrolled with respect to location and extent of cerebrovascular disease. In FTD patients, cholinesterase inhibitors were mostly associated with worsening of cognitive and behavioral symptoms. In non-AD dementias, cholinesterase inhibitors were well tolerated, with increased reports of mild to moderate cholinergic side effects and a non-significant trend for increased cardio and cerebrovascular events with rivastigmine in VaD, justifying their cautious use on a case-by-case basis, especially when there is evidence for cholinergic deficit.

A Review of Neurotransmitters Sensing Methods for Neuro-Engineering Research

Neurotransmitters as electrochemical signaling molecules are essential for proper brain function and their dysfunction is involved in several mental disorders. Therefore, the accurate detection and monitoring of these substances are crucial in brain studies. Neurotransmitters are present in the nervous system at very low concentrations, and they mixed with many other biochemical molecules and minerals, thus making their selective detection and measurement difficult. Although numerous techniques to do so have been proposed in the literature, neurotransmitter monitoring in the brain is still a challenge and the subject of ongoing research. This article reviews the current advances and trends in neurotransmitters detection techniques, including in vivo sampling and imaging techniques, electrochemical and nano-object sensing techniques for in vitro and in vivo detection, as well as spectrometric, analytical and derivatization-based methods mainly used for in vitro research. The document analyzes the strengths and weaknesses of each method, with the aim to offer selection guidelines for neuro-engineering research.

The Neuropsychological Profile and Phenomenology of Late Onset Psychosis: A Cross-sectional Study on the Differential Diagnosis of Very-Late-Onset Schizophrenia-Like Psychosis, Dementia with Lewy Bodies and Alzheimer's Type Dementia with Psychosis

Objective

Late onset psychosis not only occurs as a prodromal symptom to neurodegeneration, but it can also be associated with a non-progressive mild cognitive deficit. Studying the phenomenology of psychotic symptoms and the neuropsychological profile may serve as sensitive and non-invasive tools for differential diagnosis.

Method

We compared 57 individuals with very-late-onset schizophrenia-like psychosis (VLOSLP), 49 participants with Dementia with Lewy Bodies (DLB) and 35 patients with Alzheimer's type Dementia and psychosis (AD+P) concerning the phenomenology of psychotic symptoms and the neuropsychological profile using several measures of cognitive function in a cross-sectional study.

Results

Participants with DLB exhibited more visual hallucinations, especially those involving animals, and less partition/paranoid delusions than both other groups. VLOSLP showed more partition delusions and auditory hallucinations of human voices than both other groups. Hence, patients with DLB and VLOSLP showed greater dissimilarity in the phenomenology of psychosis, whereas individuals with AD+P held an intermediate position. Processing speed and executive function were comparably impaired among the three groups, as was expected considering a common underlying set of neurobiological abnormalities for psychosis. However, AD+P showed more strongly reduced learning and consolidation skills, whereas DLB was associated with prominent visuoconstructive deficits.

Conclusions

Phenomenology of psychosis may prove especially informative when comparing individuals with DLB to those with VLOSLP. Neuropsychological profiles are able to further aid differential diagnosis of the three groups.

Glucocerebrosidase mRNA is Diminished in Brain of Lewy Body Diseases and Changes with Disease Progression in Blood

Parkinson disease (PD) and dementia with Lewy bodies (DLB) are Lewy body diseases characterized by abnormal alpha-synuclein deposits and overlapping pathological features in the brain. Several studies have shown that glucocerebrosidase (GBA) deficiency is involved in the development of LB diseases. Here, we aimed to find out if this deficiency starts at the transcriptional level, also involves alternative splicing, and if GBA expression changes in brain are also detectable in blood of patients with LB diseases. The expression of three GBA transcript variants (GBAtv1, GBAtv2 and GBAtv5) was analyzed in samples from 20 DLB, 25 PD and 17 control brains and in blood of 20 DLB, 26 PD patients and 17 unaffected individuals. Relative mRNA expression was determined by real-time PCR. Expression changes were evaluated by the ΔΔCt method. In brain, specific expression profiles were identified in the temporal cortex of DLB and in the caudate nucleus of PD. In blood, significant GBA mRNA diminution was found in both DLB and PD patients. Early PD and early-onset DLB patients showed lowest GBA levels which were normal in PD patients with advanced disease and DLB patients who developed disease after 70 years of age. In conclusion, disease group specific GBA expression profiles were found in mostly affected areas of LBD. In blood, GBA expression was diminished in LB diseases, especially in patients with early onset DLB and in patients with early PD. Age of disease onset exerts an opposite effect on GBA expression in DLB and PD.

Alternative Splicing of Alpha- and Beta-Synuclein Genes Plays Differential Roles in Synucleinopathies

The synuclein family is composed of three members, two of which, α- and β-synuclein, play a major role in the development of synucleinopathies, including Parkinson’s disease (PD) as most important movement disorder, dementia with Lewy bodies (DLB) as the second most frequent cause of dementia after Alzheimer’s disease and multiple system atrophy. Whereas abnormal oligomerization and fibrillation of α-synuclein are now well recognized as initial steps in the development of synucleinopathies, β-synuclein is thought to be a natural α-synuclein anti-aggregant. α-synuclein is encoded by the SNCA gene, and β-synuclein by SNCB. Both genes are homologous and undergo complex splicing events. On one hand, in-frame splicing of coding exons gives rise to at least three shorter transcripts, and the functional properties of the corresponding protein isoforms are different. Another type of alternative splicing is the alternative inclusion of at least four initial exons in the case of SNCA, and two in the case of SNCB. Finally, different lengths of 3’ untranslated regions have been also reported for both genes. SNCB only expresses in the brain, but some of the numerous SNCA transcripts are also brain-specific. With the present article, we aim to provide a systematic review of disease related changes in the differential expression of the various SNCA and SNCB transcript variants in brain, blood, and non-neuronal tissue of synucleinopathies, but especially PD and DLB as major neurodegenerative disorders.

Efficacy, Safety, and Tolerability of Armodafinil Therapy for Hypersomnia Associated with Dementia with Lewy Bodies: A Pilot Study

BACKGROUND/AIMS

Hypersomnia is common in dementia with Lewy bodies (DLB). We assessed the efficacy, safety, and tolerability of armodafinil for hypersomnia associated with DLB.

METHODS

We performed a 12-week pilot trial of armodafinil therapy (125-250 mg orally daily) in DLB outpatients with hypersomnia. The patients underwent neurologic examinations, a neuropsychological battery, laboratory testing, electrocardiography, and polysomnography. Efficacy was assessed at 2, 4, 8, and 12 weeks. Safety assessment included laboratory examinations, QTc interval, and heart rate. Tolerability was assessed by analysis of adverse events. Data were analyzed using the last-observation-carried-forward method.

RESULTS

Of 20 participants, 17 completed the protocol. The median age was 72 years, most of the participants were men (80%), and most had spouses as caregivers. The Epworth Sleepiness Scale (p < 0.001), Maintenance of Wakefulness Test (p = 0.003), and Clinical Global Impression of Change (p < 0.001) scores improved at week 12. The Neuropsychiatric Inventory total score (p = 0.003), visual hallucinations (p = 0.003), and agitation (p = 0.02) improved at week 4. Caregiver overall quality of life improved at week 12 (p = 0.004). No adverse events occurred.

CONCLUSION

These pilot data suggest improvements in hypersomnia and wakefulness and reasonable safety and tolerability of armodafinil therapy in hypersomnolent patients with DLB. Our findings inform the use of pharmacologic strategies for managing hypersomnolence in these patients.

Nature and extent of person recognition impairments associated with Capgras syndrome in Lewy body dementia

Patients with Capgras syndrome (CS) adopt the delusional belief that persons well-known to them have been replaced by an imposter. Several current theoretical models of CS attribute such misidentification problems to deficits in covert recognition processes related to the generation of appropriate affective autonomic signals. These models assume intact overt recognition processes for the imposter and, more broadly, for other individuals. As such, it has been suggested that CS could reflect the "mirror-image" of prosopagnosia. The purpose of the current study was to determine whether overt person recognition abilities are indeed always spared in CS. Furthermore, we examined whether CS might be associated with any impairments in overt affective judgments of facial expressions. We pursued these goals by studying a patient with Dementia with Lewy bodies (DLB) who showed clear signs of CS, and by comparing him to another patient with DLB who did not experience CS, as well as to a group of healthy control participants. Clinical magnetic resonance imaging scans revealed medial prefrontal cortex (mPFC) atrophy that appeared to be uniquely associated with the presence CS. We assessed overt person recognition with three fame recognition tasks, using faces, voices, and names as cues. We also included measures of confidence and probed pertinent semantic knowledge. In addition, participants rated the intensity of fearful facial expressions. We found that CS was associated with overt person recognition deficits when probed with faces and voices, but not with names. Critically, these deficits were not present in the DLB patient without CS. In addition, CS was associated with impairments in overt judgments of affect intensity. Taken together, our findings cast doubt on the traditional view that CS is the mirror-image of prosopagnosia and that it spares overt recognition abilities. These findings can still be accommodated by models of CS that emphasize deficits in autonomic responding, to the extent that the potential role of interoceptive awareness in overt judgments is taken into account.

Preclinical polymodal hallucinations for 13 years before dementia with Lewy bodies

Objective. We describe a case of dementia with Lewy bodies (DLB) that presented long-lasting preclinical complex polymodal hallucinations. Background. Few studies have deeply investigated the characteristics of hallucinations in DLB, especially in the preclinical phase. Moreover, the clinical phenotype of mild cognitive impairment-(MCI-) DLB is poorly understood. Methods. The patient was followed for 4 years and a selective phenomenological and cognitive study was performed at the predementia stage. Results. The phenomenological study showed the presence of hypnagogic and hypnopompic hallucinations that allowed us to make a differential diagnosis between DLB and Charles Bonnet syndrome (CBS). The neuropsychological evaluation showed a multiple domain without amnesia MCI subtype with prefrontal dysexecutive, visuoperceptual, and visuospatial impairments and simultanagnosia, which has not previously been reported in MCI-DLB. Conclusions. This study extends the prognostic value of hallucinations for DLB to the preclinical phases. It supports and refines the MCI-DLB concept and identifies simultanagnosia as a possible early cognitive marker. Finally, it confirms an association between hallucinations and visuoperceptual impairments at an intermediate stage of the disease course and strongly supports the hypothesis that hallucinations in the earliest stages of DLB may reflect a narcolepsy-like REM-sleep disorder.

The usefulness of monitoring sleep talking for the diagnosis of Dementia with Lewy bodies

BACKGROUND

Dementia with Lewy bodies (DLB) is the second most common type of neurodegenerative dementia. It is frequently difficult to differentiate DLB from Alzheimer's disease (AD) and other types of dementia. This study examined the usefulness of monitoring sleep talking for the diagnosis of DLB.

METHODS

A total of 317 patients with dementia were selected from a consecutive series at the Dementia Clinic of Kumamoto University Hospital. Diagnostic categories consisted of probable DLB (n = 55), probable AD (n = 191), frontotemporal lobar degeneration (FTLD) (n = 16), vascular dementia (VaD) (n = 18), and other/unspecified dementia (n = 37). We evaluated sleep talking in all dementia patients and normal elderly subjects (n = 32) using an originally designed sleep talking questionnaire.

RESULTS

Sleep talking occurred most frequently in the DLB group (61.8%), followed by the VaD group (33.3%), other/unspecified dementia group (27.0%), AD group (18.8%), FTLD group (12.5%), and normal elderly subjects group (6.3%). The prevalence of sleep talking in the DLB group was significantly higher than in other groups, except in the VaD group. The sleep talking yielded high specificity (81.2%) and some sensitivity (61.8%) for the differential diagnosis of DLB from AD. Furthermore, loud sleep talking may improve the specificity (96.9%). For the differentiation of DLB from all other dementia types, the specificity of sleep talking and loud sleep talking was also high (79.4% and 95.8% respectively).

CONCLUSIONS

Assessing sleep talking, especially the volume of sleep talking, may be useful in the clinical discrimination of DLB from not only AD but also from all other types of dementia.

Cognitive impairment, decline and fluctuations in older community-dwelling subjects with Lewy bodies

Lewy bodies are common in the ageing brain and often co-occur with Alzheimer's disease pathology. There is little known regarding the independent role of Lewy body pathology in cognition impairment, decline and fluctuations in community-dwelling older persons. We examined the contribution of Lewy body pathology to dementia, global cognition, cognitive domains, cognitive decline and fluctuations in 872 autopsied subjects (mean age = 87.9 years) from the Rush Religious Order Study (n = 491) and Memory and Aging Project (n = 381) longitudinal community-based clinical-pathological studies. Dementia was based on a clinical evaluation; annual cognitive performance tests were used to create a measure of global cognition and five cognitive domains. Lewy body type was determined by using α-synuclein immunostained sections of substantia nigra, limbic and neocortical regions. Statistical models included multiple regression models for dementia and cognition and mixed effects models for decline. Cognitive fluctuations were estimated by comparing standard deviations of individual residuals from mean trajectories of decline in those with and without Lewy bodies. All models controlled for age, sex, education, Alzheimer's disease pathology and infarcts. One hundred and fifty-seven subjects (18%) exhibited Lewy body pathology (76 neocortical-type, 54 limbic-type and 27 nigra-predominant). One hundred and three (66%) subjects with Lewy body pathology had a pathologic diagnosis of Alzheimer's disease. Neocortical-type, but not nigral-predominant or limbic-type Lewy body pathology was related to an increased odds of dementia (odds ratio = 3.21; 95% confidence interval = 1.78-5.81) and lower cognition (P < 0.001) including episodic memory function (P < 0.001) proximate to death. Neocortical-type Lewy body pathology was also related to a faster decline in global cognition (P < 0.001), decline in all five specific cognitive domains (all P-values < 0.001), and to fluctuations in decline of working and semantic memory (P-values < 0.001). Limbic-type Lewy body pathology was related to lower and faster decline in visuospatial skills (P = 0.042). The relationship of Lewy body pathology to cognition and dementia was not modified by Alzheimer's disease pathology. Neocortical-type Lewy body pathology is associated with increased odds of dementia; lower and more rapid decline in all cognitive domains including episodic memory and fluctuations in decline in semantic and working memory. Limbic-type Lewy body pathology is specifically associated with lower and more rapid decline in visuospatial skills. The effect of Lewy body pathology on cognition appears to be independent of Alzheimer's disease pathology.

New brain-specific beta-synuclein isoforms show expression ratio changes in Lewy body diseases

Lewy body diseases (LBDs) include dementia with Lewy bodies (DLB) and Parkinson disease (PD). Alpha-synuclein (AS) aggregation is a key event in the pathogenesis of LBDs and beta-synuclein (BS) inhibits AS aggregation in vitro and in vivo. Recently, BS has been shown to interact directly with AS regulating its functionality and preventing its oligomerization, and a molecular subgroup of pure DLB lacks BS in cortical regions. In this study, we characterized four new BS transcript variants and analyzed their expression in neuronal and non-neuronal tissue, and their differential expression in frozen samples of three areas from brains of patients with pure Lewy body pathology (LBP), common LBP, Alzheimer pathology, and of controls. Relative mRNA expression was determined by real-time PCR with neuron-specific enolase 2 and synaptophysin as housekeeping genes, and expression changes were evaluated by the ΔΔCt method. Two main findings are in concordance with earlier studies. First, all BS isoforms are drastically diminished in the cortex of patients with pure LBP that had presented clinically as DLB but not PD with dementia. Second, an important shift of the isoform expression ratio was observed in the temporal cortex of all LBD cases, and the minor isoforms, normally absent in the midbrain, were detected in the caudate nucleus of all DLB samples. Our results provide further evidence for the role of minor transcript variants in the development of complex diseases and provide new insights into the pathogenesis of LBDs that may be important for the understanding of molecular mechanisms involved in these complex diseases.

[Symptoms of Lewy body dementia and clinical course compared with Alzheimer's disease]

Lewy body dementia (LBD) is a neurodegenerative disease with well-defined symptoms and established clinical criteria, characterized by the presence of cortical and subcortical dementia, accompanied by some characteristic features such as Parkinsonism, visual hallucinations and fluctuations in alertness and attention, as well as hypersensitivity to neuroleptics. Compared with Alzheimer's disease, LBD seems to have a more rapid clinical course and greater mortality. The differences with Alzheimer's disease may be more apparent in the initial stages of the disease but tend to disappear with disease progression. Because of the greater presence of neuropsychiatric symptoms and the higher degree of dependency in LBD, there is greater caregiver overload and probably greater resource use.

Alpha- and beta-synuclein expression in Parkinson disease with and without dementia

Parkinson disease (PD) is the most important movement disorder and about 50% of patients develop dementia over the time. PD belongs to the group of Lewy body disorders. Alpha-synuclein (AS) is the main component of Lewy bodies and its aggregation is a key event in the pathogenesis of PD. Beta-synuclein (BS) inhibits AS aggregation in vitro and in vivo and has been shown to interact directly with AS regulating its functionality and preventing its oligomerization. Recently, we have described a molecular subgroup of DLB characterized by the drastic BS reduction in cortical areas. In this study we have analyzed the expression of two BS transcripts and the main AS transcript SNCA140, in frozen samples of three brain areas, temporal cortex, caudate nucleus and pons, from patients with PD and PDD in comparison with controls. Relative mRNA expression was determined by real-time PCR with SybrGreen, neuron-specific-enolase as housekeeping gene and the deltadeltaCt method. The most important difference in BS and AS mRNA expression between PD and PDD was found in the caudate nucleus, where BS mRNA was overexpressed in PD and AS mRNA diminished in PDD. Our findings provide new insights into the pathogenesis of dementia in PD, indicating that differential BS and AS expression in the caudate nucleus may represent one of the molecular mechanisms involved in these complex diseases.

The decrease of β-synuclein in cortical brain areas defines a molecular subgroup of dementia with Lewy bodies

Lewy body diseases include dementia with Lewy bodies and Parkinson's disease. Whereas dementia with Lewy bodies and Parkinson's disease can be distinguished as separate clinical entities, the pathological picture is very often identical. α-synuclein aggregation is a key event in the pathogenesis of Lewy body diseases and β-synuclein inhibits α-synuclein aggregation in vitro and in vivo. Recently, β-synuclein has been shown to interact directly with α-synuclein, regulating its functionality and preventing its oligomerization. In this study, we analysed the expression of two β-synuclein transcript variants and the main α-synuclein transcript SNCA140, in frozen samples of three areas from brains of patients with (i) pure diffuse Lewy body pathology; (ii) pure Alzheimer's disease pathology; (iii) diffuse Lewy body pathology and concomitant Alzheimer's disease pathology and (iv) controls. Relative messenger RNA expression was determined by real-time polymerase chain reaction, expression changes were evaluated by the ΔΔC(t) method and messenger RNA expression data were confirmed at the protein level. A drastic diminution of β-synuclein expression was observed in cortical areas of all samples that presented neuropathological features corresponding to pure diffuse Lewy body pathology and the clinical phenotype of dementia with Lewy bodies, but not in those with neuropathological features corresponding to diffuse Lewy body pathology and concomitant Alzheimer's disease pathology or the clinical phenotype of Parkinson's disease with dementia. The correlation of expression data with the clinical phenotype and neuropathological diagnosis of the patients suggested the existence of a specific molecular subtype of dementia with Lewy bodies, characterized by a strong decrease of β-synuclein in the frontal and temporal cortices. Furthermore, our findings provide new insights into the pathogenesis of Lewy body diseases that may be important for the understanding of molecular mechanisms involved in these complex diseases.

Recent insights into the molecular genetics of dementia

Our understanding of the molecular genetic basis of two common neurodegenerative dementias, Alzheimer's disease (AD) and frontotemporal lobar degeneration (FTLD), has greatly advanced in recent years. Progranulin mutations were identified as a major cause of FTLD and a potential susceptibility factor for other forms of dementia. In addition, through copy-number analyses of previously identified disease genes and the study of microRNA regulation in dementia, new evidence emerged to support the view that subtle variability in the expression of known disease proteins could increase the risk for sporadic forms of dementia. Finally, in late-onset AD populations, the first genome-wide association studies were performed and novel potential AD susceptibility genes reported. These exciting findings provide novel insights into the disease mechanisms underlying dementia and hold promise for the development of potential treatments.

The clinical and pathophysiological relevance of REM sleep behavior disorder in neurodegenerative diseases

REM sleep behavior disorder (RBD) is characterized by vigorous movements associated with unpleasant dreams and increased electromyographic activity during REM sleep. Polysomnography with audiovisual recording is needed to confirm the diagnosis of RBD and to exclude other sleep disorders that can mimic its symptoms including obstructive sleep apnea, nocturnal hallucinations and confusional awakenings. RBD may be idiopathic or related to neurodegenerative diseases, particularly multiple system atrophy, Parkinson's disease and dementia with Lewy bodies. RBD may be the first manifestation of these disorders, antedating the onset of parkinsonism, cerebellar syndrome, dysautonomia, and dementia by several years. RBD should thus be considered an integral part of the disease process. When effective, neuroprotective strategies should be considered in subjects with idiopathic RBD. Patients with other neurodegenerative diseases, though, such as spinocerebellar ataxias, may also present with RBD. When clinically required, clonazepam at bedtime is effective in decreasing the intensity of dream-enacting behaviors and unpleasant dreams in both the idiopathic and secondary forms. When part of a neurodegenerative disorder the development of RBD is thought to reflect the location and extent of the underlying lesions involving the REM sleep centers of the brain (e.g., locus subceruleus, amygdala, etc.), leading to a complex multiple neurotransmitter dysfunction that involves GABAergic, glutamatergic and monoaminergic systems. RBD is mediated neither by direct abnormal alpha-synuclein inclusions nor by striatonigral dopaminergic deficiency alone.

Prodromal clinical manifestations of neuropathologically confirmed Lewy body disease

The mild cognitive impairment (MCI) stage of dementia with Lewy bodies (MCI-DLB) has not yet been defined, but is likely to differ in the MCI stage of Alzheimer's disease (MCI-AD). To determine whether clinical features distinguish MCI-DLB and MCI-AD, 9 cases of neuropathologically confirmed MCI-DLB and 12 cases of MCI-AD were compared. No significant differences were found between MCI-DLB and MCI-AD cases in age at death, gender, ApoE status, education, time followed while clinically normal, or duration of MCI. MCI-DLB and MCI-AD cases differed clinically in the expression of Parkinsonism (P=0.012), provoked hallucinations or delirium (P=0.042), or the presence of any of these noncognitive symptoms of DLB (P<0.0001). Letter fluency (P=0.007) was significantly lower and Wechsler Logical Memory I (P=0.019) was significantly higher in MCI-DLB compared to MCI-AD cases. These data demonstrate the feasibility of differentiating underlying pathologic processes responsible for cognitive decline in the preclinical disease state and suggest that further refinement in diagnostic criteria may allow more accurate early detection of prodromal DLB and AD.

Mitochondrial DNA, base excision repair and neurodegeneration

Neurodegeneration is a growing public health concern because of the rapid increase in median and maximum life expectancy in the developed world. Mitochondrial dysfunction seems to play a critical role in neurodegeneration, likely owing to the high energy demand of the central nervous system and its sole reliance on oxidative metabolism for energy production. Loss of mitochondrial function has been clearly demonstrated in several neuropathologies, most notably those associated with age, like Alzheimer's, Parkinson's and Huntington's diseases. Among the common features observed in such conditions is the accumulation of oxidative DNA damage, in particular in the mitochondrial DNA, suggesting that mitochondrial DNA instability may play a causative role in the development of these diseases. In this review we examine the evidence for the accumulation of oxidative DNA damage in mitochondria, and its relationship with loss of mitochondrial function and cell death in neural tissues. Oxidative DNA damage is repaired mainly by the base excision repair pathway. Thus, we review the molecular events and enzymes involved in base excision repair in mitochondria, and explore the possible role of alterations in mitochondrial base excision repair activities in premature aging and age-associated neurodegenerative diseases.