Are Parkinson's disease with dementia and dementia with Lewy bodies the same entity?

Amyloid PET Imaging in Lewy body disorders

Lewy body (LB) disorders, including Parkinson disease (PD), Parkinson disease dementia (PDD), and dementia with Lewy bodies (DLB), are the second most common type of neurodegenerative dementia. Although the pathological hallmarks of LB disorders are Lewy bodies and Lewy neurites, cortical amyloid-beta (Aβ) deposition is also often seen. The relationship between Aβ pathology and dementia in LB disorders is unclear. Recently, positron emission tomography Aβ ligands have been developed that enable in vivo imaging of Aβ. In this paper we review amyloid imaging studies in LB disorders. LB disorders are associated with lower mean cortical Aβ ligand binding compared with Alzheimer disease. In DLB and PDD many subjects have normal levels of cortical Aβ, though a subset show increased Aβ ligand binding. Those with DLB show greater ligand binding than PDD; binding does not appear to be increased in PD without dementia. Cortical Aβ deposition may be a factor in the development of cognitive impairment in some cases of dementia in LB disorders. Amyloid imaging is of limited use in the diagnosis of LB disorders but Aβ deposition may predict the future development of dementia in PD. Reports of correlation between Aβ deposition and symptom profile, severity, and progression have been inconsistent. Some results suggest a synergistic interaction between Aβ and α-synuclein. Interpretation of the current evidence is hampered by differing methodologies across studies and small sample sizes. Large, prospective longitudinal studies are needed to clarify the association of Aβ with symptom development, progression, severity, and treatment response in LB disorders.

Persistence and Prognostic Implications of Orthostatic Hypotension in Older Individuals with Mild-to-Moderate Dementia

AIM

To study the course and prognostic implications of orthostatic hypotension (OH) in older individuals with mild-to-moderate dementia.

METHODS

Referrals to outpatient clinics specialising in old age psychiatry and geriatric medicine in the counties of Rogaland and Hordaland in western Norway with a first-time diagnosis of mild dementia were consecutively asked for inclusion. A total of 211 participants underwent a comprehensive baseline assessment with annual follow-ups. Patients with OH at both baseline and the 1-year follow-up were classified as having persistent OH. Outcome measures were the Mini-Mental State Examination (MMSE), the Clinical Dementia Rating sum of boxes (CDR-SB), and time to death.

RESULTS

From baseline to the 4-year follow-up, 30-45% of the participants had OH at each follow-up. In multivariable analysis, persistent OH was not significantly associated with either the longitudinal course of MMSE or CDR-SB scores or survival.

CONCLUSIONS

OH was moderately prevalent over 4 years in older individuals with mild dementia, and persistent OH did not predict either cognitive or functional decline or survival.

Treatment effect of memantine on survival in dementia with Lewy bodies and Parkinson's disease with dementia: a prospective study

OBJECTIVE

To investigate the effect on survival of treatment with memantine in patients with dementia with Lewy bodies (DLB) and Parkinson's disease with dementia (PDD).

METHODS

75 patients with DLB and PDD were included in a prospective double-blinded randomised placebo-controlled trial (RCT) of memantine, of whom long-term follow-up was available for 42. Treatment response was recorded 24 weeks from baseline and measured by Clinical Global Impression of Change (CGIC). The participants were grouped as responders (CGIC 1-3) or non-responders (CGIC 4-7). The 24-week RCT was followed by open-label treatment and survival was recorded at 36 months.

RESULTS

After 36-month follow-up, patients in the memantine group had a longer length of survival compared with patients in the placebo group (log rank x²=4.02, p=0.045). Within the active treatment group, survival analysis 36 months from baseline showed that the memantine responders, based on CGIC, had higher rates of survival compared with the non-responders (log rank x²=6.595, p=0.010). Similar results were not seen in the placebo group.

CONCLUSIONS

Early treatment with memantine and a positive clinical response to memantine predicted longer survival in patients with DLB and PDD. This suggests a possible disease-modifying effect and also has implications for health economic analysis. However, owing to the small study sample, our results should merely be considered as generating a hypothesis which needs to be evaluated in larger studies.

TRIAL REGISTRATION NUMBER

ISRCTN89624516.

Determining the association of the 5HTTLPR polymorphism with delusions and hallucinations in Lewy body dementias

OBJECTIVES

To determine whether the 5HTTLPR serotonin transporter polymorphism is associated with delusions and hallucinations in people with dementia with Lewy bodies (DLB) and Parkinson disease dementia (PDD).

DESIGN

Prospective cohort study.

PARTICIPANTS

A total of 187 individuals, recruited from centres in Norway, Sweden, and the United Kingdom were included in this study; 97 with clinically or neuropathologically diagnosed DLB/PDD and 90 cognitively normal individuals as a comparison group.

MEASUREMENTS

All participants with dementia underwent serial evaluation of neuropsychiatric symptoms to assess the presence of persistent delusions and hallucinations using the Columbia University Scale for Psychopathology in Alzheimer disease, the Neuropsychiatric Inventory, or the Present Behavioural Examination. Severity of cognitive impairment was measured using the Mini Mental State Examination (MMSE). Individuals were genotyped for the 5HTTLPR polymorphism.

RESULTS

Logistic regression demonstrated that homozygosity for the L/L genotype and lower MMSE were associated with an increased risk for delusions (odds ratio: 11.5 and 1.16, respectively). Neither was significantly associated with hallucinations.

CONCLUSIONS

This study is the first to demonstrate the 5HTTLPR polymorphism is associated with delusions in Lewy body dementias, with important implications regarding the mechanisms underlying this symptom across the AD/DLB/PDD spectrum. Further studies are warranted to investigate this relationship further and examine treatment opportunities.

The spectrum of cognitive impairment in Lewy body diseases

Cognitive impairment represents an important and often defining component of the clinical syndromes of Lewy body disorders: Parkinson's disease and dementia with Lewy bodies. The spectrum of cognitive deficits in these Lewy body diseases encompasses a broad range of clinical features, severity of impairment, and timing of presentation. It is now recognized that cognitive dysfunction occurs not only in more advanced Parkinson's disease but also in early, untreated patients and even in those patients with pre-motor syndromes, such as rapid eye movement behavior disorder and hyposmia. In recent years, the concept of mild cognitive impairment as a transitional or pre-dementia state in Parkinson's disease has emerged. This has led to much research regarding the diagnosis, prognosis, and underlying neurobiology of mild cognitive impairment in Parkinson's disease, but has also raised questions regarding the usefulness of this concept and its application in clinical and research settings. In addition, the conundrum of whether Parkinson's disease dementia and dementia with Lewy bodies represent the same or different entities remains unresolved. Although these disorders overlap in many aspects of their presentations and pathophysiology, they differ in other elements, such as timing of cognitive, behavioral, and motor symptoms; medication responses; and neuropathological contributions. This article examines the spectrum and evolution of cognitive impairment in Lewy body disorders and debates these controversial issues in the field using point-counterpoint approaches.

UPDATE ON DEMENTIA WITH LEWY BODIES

Dementia with Lewy bodies (DLB) is the second most common form of dementia after Alzheimer disease (AD). DLB is characterized pathologically by Lewy body and Lewy neuritic pathology, often with variable levels of Alzheimer-type pathology. Core clinical features include fluctuating cognition, visual hallucinations, and parkinsonism resulting in greater impairments of quality of life, more caregiver burden, and higher health-related costs compared with AD. These issues, together with a high sensitivity to adverse events with treatment with antipsychotic agents, make the need for an early and accurate diagnosis of DLB essential. Unfortunately, current consensus criteria are highly specific but lack sufficient sensitivity. Use of composite risk scores may improve accuracy of clinical diagnosis. Imaging findings, particularly targeting dopaminergic systems have shown promise as potential markers to differentiate DLB from AD. A combination of non-pharmacologic treatments and pharmacotherapy interventions may maximize cognitive function and overall quality of life in DLB patients.

Neuropathological alterations in Alzheimer disease

The neuropathological hallmarks of Alzheimer disease (AD) include "positive" lesions such as amyloid plaques and cerebral amyloid angiopathy, neurofibrillary tangles, and glial responses, and "negative" lesions such as neuronal and synaptic loss. Despite their inherently cross-sectional nature, postmortem studies have enabled the staging of the progression of both amyloid and tangle pathologies, and, consequently, the development of diagnostic criteria that are now used worldwide. In addition, clinicopathological correlation studies have been crucial to generate hypotheses about the pathophysiology of the disease, by establishing that there is a continuum between "normal" aging and AD dementia, and that the amyloid plaque build-up occurs primarily before the onset of cognitive deficits, while neurofibrillary tangles, neuron loss, and particularly synaptic loss, parallel the progression of cognitive decline. Importantly, these cross-sectional neuropathological data have been largely validated by longitudinal in vivo studies using modern imaging biomarkers such as amyloid PET and volumetric MRI.

Can we clinically diagnose dementia with Lewy bodies yet?

Dementia with Lewy Bodies (DLB) was initially identified and confirmed primarily by pathology, but is soon to be incorporated into the Diagnostic and Statistical Manual criteria as a clinical disease entity. Despite these advances over more than 20 years, current data suggest that the sensitivity of accurate clinical diagnosis of DLB is still very low, although there is mounting evidence that supportive features may increase diagnostic accuracy. Although DLB remains easy to identify pathologically with different cellular pathologies differentiating it from other dementia syndromes, pathological identification using only Lewy body pathology has been shown to be inaccurate due to overlap with patients without dementia symptoms. A number of studies now suggest that a combination of cellular pathologies, which include α-synuclein and β-amyloid deposition as well as dopamine denervation, assist with differentiating this dementia syndrome from others. The clinical and pathological overlap with the tauopathy of Alzheimer's disease still remains to be clarified. To determine more robust and independent clinicopathological correlates from Alzheimer's disease, longitudinal prospective studies, using specific clinical batteries on dementia patients reaching the proposed criteria for DLB, with post-mortem assessment of the multiple pathologies associated with dementia, are required. Identifying genetic causes for DLB is another approach to investigate the pathogenesis of DLB. However this approach has been hindered to date by difficulties with identifying DLB clinically. The use of novel techniques is likely to advance knowledge on the pathogenesis of DLB and assist with redefining clinical and pathologic diagnostic criteria. To achieve the goal of more accurate clinical diagnosis of DLB, breakthroughs are necessary on the pathogenesis of DLB.

Neuropsychiatric symptoms in mild dementia with lewy bodies and Alzheimer's disease

BACKGROUND/AIMS

To compare neuropsychiatric symptoms in patients with Alzheimer's disease (AD) and dementia with Lewy bodies(DLB).

METHODS

Neuropsychiatric symptoms and caregiver distress were assessed using the Neuropsychiatric Inventory (NPI) in mild DLB (n = 57) and AD (n = 126), and compared across the two groups using non-parametric tests.

RESULTS

The DLB patients had a higher NPI totalscore (median 24 vs. 11.5, p < 0.005), more numerous symptoms (median 5 vs. 4, p = 0.001) and more clinically significant symptoms (3 vs. 1, p = 0.001). They also had higher item hallucinations (6 vs. 2, p < 0.005) and apathy (7 vs. 5, p = 0.002) subscores. Caregivers scored higher on the NPI total caregiver distress scale (12.5 vs. 6, p = 0.003).

CONCLUSIONS

In mild dementia, DLB patients have more neuropsychiatric symptoms and more associated caregiver distress compared with AD.

Relationship between orthostatic hypotension and white matter hyperintensity load in older patients with mild dementia

Background/Objectives

White matter hyperintensities (WMH) in magnetic resonance imaging (MRI) scans of the brain, and orthostatic hypotension (OH) are both common in older people. We tested the hypothesis that OH is associated with WMH.

Design

Cross-sectional study.

Setting

Secondary care outpatient clinics in geriatric medicine and old age psychiatry in western Norway.

Participants

160 older patients with mild dementia, diagnosed according to standardised criteria.

Measurements

OH was diagnosed according to the consensus definition, measuring blood pressure (BP) in the supine position and within 3 minutes in the standing position. MRI scans were performed according to a common protocol at three centres, and the volumes of WMH were quantified using an automated method (n = 82), followed by manual editing. WMH were also quantified using the visual Scheltens scale (n = 139). Multiple logistic regression analyses were applied, with highest vs. lowest WMH quartile as response.

Results

There were no significant correlations between WMH volumes and systolic or diastolic orthostatic BP drops, and no significant correlations between Scheltens scores of WMH and systolic or diastolic BP drops. In the multivariate analyses, only APOEε4 status remained a significant predictor for WMH using the automated method (p = 0.037, OR 0.075 (0.007–0.851)), whereas only age remained a significant predictor for WMH scores (p = 0.019, OR 1.119 (1.018–1.230)).

Conclusion

We found no association between OH and WMH load in a sample of older patients with mild dementia.

White matter hyperintensities in mild lewy body dementia

Background

The objective of this study was to explore the load of white matter hyperintensities (WMH) in patients with Lewy body dementia (LBD) and compare to Alzheimer's disease (AD) and normal controls (NC).

Methods

Diagnosis of LBD and AD was made according to consensus criteria and cognitive tests were administered. MRI scans for 77 (61 AD and 16 LBD) patients and 37 healthy elderly control subjects were available for analysis. We segmented WMH from FLAIR images using an automatic thresholding technique and calculated the volume of WMH in several regions of the brain, using non-parametric tests to compare groups. Multivariate regression was applied.

Results

There were no significant differences in WMH between AD and LBD. We found a significant correlation between total and frontal WMH and Mini-Mental State Examination (MMSE) and verbal fluency scores in the AD group, but not in the LBD group.

Conclusion

The WMH load in LBD was similar to that of AD. A correlation between WMH load and cognition was found in the AD group, but not in the LBD group, suggesting that vascular disease contributes to cognitive impairment in AD but not LBD.

Small-vessel disease in patients with Parkinson's disease: a clinicopathological study

Few studies have examined the relationship between cerebrovascular disease, vascular risk factors, and Parkinson's disease (PD), although 1 study found small-vessel disease (SVD) to be the main subtype of cerebrovascular disease. In this study we compared the extent and topography of SVD and assessed associated vascular risk factors in autopsy-proven PD cases and community-dwelling controls. Seventy-seven PD and 32 control brains from the Sydney Brain Bank were assessed microscopically by a single examiner blinded to the diagnosis. SVD was assessed by grading perivascular pallor, gliosis, hyaline thickening, and enlargement of perivascular spaces in the white matter underlying the superior frontal and primary motor cortices, basal ganglia, and white matter tracts. A history of vascular risk factors (hypertension, heart disease, diabetes, and cigarette smoking) was obtained. Groups were compared using stepwise multiple regression analysis. There was significantly greater frontal pallor (P = .004) and widening of perivascular spaces in the globus pallidus interna (P = .007) in controls compared with PD. Hyaline thickening and widening of perivascular spaces in the frontal white matter, hyaline thickening in the motor white matter, and widening of perivascular spaces in the caudate nucleus were more common in the control group, but did not reach significance. The prevalence of vascular risk factors and SVD pathology was significantly lower in autopsy-proven PD compared with controls (P = .03) living in the same community. The results of this study support the need for further research in this area.

Autophagy in dementias

Dementias are a varied group of disorders typically associated with memory loss, impaired judgment and/or language and by symptoms affecting other cognitive and social abilities to a degree that interferes with daily functioning. Alzheimer's disease (AD) is the most common cause of a progressive dementia, followed by dementia with Lewy bodies (DLB), frontotemporal dementia (FTD), (VaD) and HIV-associated neurocognitive disorders (HAND). The pathogenesis of this group of disorders has been linked to the abnormal accumulation of proteins in the brains of affected individuals, which in turn has been related to deficits in protein clearance. Autophagy is a key cellular protein clearance pathway with proteolytic cleavage and degradation via the ubiquitin-proteasome pathway representing another important clearance mechanism. Alterations in the levels of autophagy and the proteins associated with the autophagocytic pathway have been reported in various types of dementias. This review will examine recent literature across these disorders and highlight a common theme of altered autophagy across the spectrum of the dementias.

Neuroimaging of dementia with Lewy bodies

Dementia with Lewy bodies (DLB) is a relative newcomer to the field of late-life dementia. Although a diversity of imaging methodologies is now available for the study of dementia, these have been applied most often to Alzheimer's disease (AD). Studies on DLB, although fewer, have yielded fascinating and important insights into the underlying pathophysiology of this condition and allowed clinical differentiation of DLB from other dementias. Imaging research on DLB has had significant ramifications in terms of raising the profile of DLB and helping define it as a distinctive and separate disease entity from AD.

Dementia in Parkinson's Disease Correlates with α-Synuclein Pathology but Not with Cortical Astrogliosis

Dementia is a common feature in Parkinson's disease (PD) and is considered to be the result of limbic and cortical Lewy bodies and/or Alzheimer changes. Astrogliosis may also affect the development of dementia, since it correlates well with declining cognition in Alzheimer patients. Thus, we determined whether cortical astrogliosis occurs in PD, whether it is related to dementia, and whether this is reflected by the presence of glial fibrillary acidic protein (GFAP) and vimentin in cerebrospinal fluid (CSF). We have examined these proteins by immunohistochemistry in the frontal cortex and by Western blot in CSF of cases with PD, PD with dementia (PDD), dementia with Lewy bodies (DLB) and nondemented controls. We were neither able to detect an increase in cortical astrogliosis in PD, PDD, or DLB nor could we observe a correlation between the extent of astrogliosis and the degree of dementia. The levels of GFAP and vimentin in CSF did not correlate to the extent of astrogliosis or dementia. We did confirm the previously identified positive correlation between the presence of cortical Lewy bodies and dementia in PD. In conclusion, we have shown that cortical astrogliosis is not associated with the cognitive decline in Lewy body-related dementia.

White matter hyperintensities and the course of depressive symptoms in elderly people with mild dementia

Objectives

To explore the relationship between white matter hyperintensities (WMH) and the prevalence and course of depressive symptoms in mild Alzheimer's disease (AD) and Lewy body dementia. Design: This is a prospective cohort study conducted in secondary care outpatient clinics in western Norway. Subjects: The study population consisted of 77 elderly people with mild dementia diagnosed according to standardised criteria.

Methods

Structured clinical interviews and physical, neurological, psychiatric, and neuropsychological examinations were performed and routine blood tests were taken. Depression was assessed using the depression subitem of the Neuropsychiatric Inventory and the Montgomery-Åsberg Depression Rating Scale (MADRS). A standardised protocol for magnetic resonance imaging scan was used, and the volumes of WMH were quantified using an automated method, followed by manual editing.

Results

The volumes of total and frontal deep WMH were significantly and positively correlated with baseline severity of depressive symptoms, and depressed patients had significantly higher volumes of total and frontal deep WMH than non-depressed patients. Higher volumes of WMH were also associated with having a high MADRS score and incident and persistent depression at follow-up. After adjustment for potential confounders, frontal deep WMH, in addition to prior depression and non-AD dementia, were still significantly associated with baseline depressive symptoms (p = 0.015, OR 3.703, 95% CI 1.294–10.593). Similar results emerged for total WMH.

Conclusion

In elderly people with mild dementia, volumes of WMH, in particular frontal deep WMH, were positively correlated with baseline severity of depressive symptoms, and seemed to be associated with persistent and incident depression at follow-up. Further studies of the mechanisms that determine the course of depression in mild dementia are needed.

Sentence processing in Lewy body spectrum disorder: the role of working memory

Prior work has related sentence processing to executive deficits in non-demented patients with Parkinson's disease (PD). We extended this investigation to patients with dementia with Lewy bodies (DLB) and PD dementia (PDD) by examining grammatical and working memory components of sentence processing in the full range of patients with Lewy body spectrum disorder (LBSD). Thirty-three patients with LBSD were given a two-alternative, forced-choice sentence-picture matching task. Sentence type, working memory, and grammatical structure were systematically manipulated in the sentences. We found that patients with PDD and DLB were significantly impaired relative to non-demented PD patients and healthy controls. The deficit in PDD/DLB was most pronounced for sentences lengthened by the strategic placement of an additional prepositional phrase and for sentences with an additional proposition due to a center-embedded clause. However, there was no effect for subject-relative versus object-relative grammatical structure. An MRI voxel-based morphometry analysis in a subset of patients showed significant gray matter thinning in the frontal lobe bilaterally, and this extended to temporal, parietal and occipital regions. A regression analysis related sentence processing difficulty in LBSD to frontal neocortex, including inferior prefrontal, premotor, and dorsolateral prefrontal regions, as well as right superior temporal cortex. These findings are consistent with the hypothesis that patients with PDD and DLB have difficulty processing sentences with increased working memory demands and that this deficit is related in part to their frontal disease.

Staging neurodegenerative disorders: structural, regional, biomarker, and functional progressions

The notion of staging in the neurodegenerative disorders is modulated by the constant and progressive loss of several aspects of brain structural integrity, circuitry, and neuronal processes. These destructive processes eventually remove individuals' abilities to perform at sufficient and necessary functional capacity at several levels of disease severity. The classification of (a) patients on the basis of diagnosis, risk prognosis, and intervention outcome, forms the basis of clinical staging, and (b) laboratory animals on the basis of animal model of brain disorder, extent of insult, and dysfunctional expression, provides the components for the clinical staging and preclinical staging, respectively, expressing associated epidemiological, biological, and genetic characteristics. The major focus of clinical staging in the present account stems from the fundamental notions of Braak staging as they describe the course and eventual prognosis for Alzheimer's disease, Lewy Body dementia, and Parkinson's disease. Mild cognitive impairment, which expresses the decline in episodic and semantic memory performance below the age-adjusted normal range without marked loss of global cognition or activities of daily living, and the applications of longitudinal magnetic resonance imaging, major instruments for the monitoring of either disease progression in dementia, present important challenges for staging concepts. Although Braak notions present the essential basis for further developments, current staging conceptualizations seem inadequate to comply with the massive influx of information dealing with neurodegenerative processes in brain, advanced both under clinical realities, and discoveries in the laboratory setting. The contributions of various biomarkers of disease progression, e.g., amyloid precursor protein, and neurotransmitter system imbalances, e.g., dopamine receptor supersensitivity and interactive propensities, await their incorporation into the existing staging models thereby underlining the ongoing, dynamic feature of the staging of brain disorders.

Neuropathology underlying clinical variability in patients with synucleinopathies

Abnormal aggregates of the synaptic protein, α-synuclein, are the dominant pathology in syndromes known as the synucleinopathies. The cellular aggregation of the protein occurs in three distinct types of inclusions in three main clinical syndromes. α-Synuclein deposits in neuronal Lewy bodies and Lewy neurites in idiopathic Parkinson's disease (PD) and dementia with Lewy bodies (DLB), as well as incidentally in a number of other conditions. In contrast, α-synuclein deposits largely in oligodendroglial cytoplasmic inclusions in multiple system atrophy (MSA). Lastly, α-synuclein also deposits in large axonal spheroids in a number of rarer neuroaxonal dystrophies. Disorders are usually defined by their most dominant pathology, but for the synucleinopathies, clinical heterogeneity within the main syndromes is well documented. MSA was originally viewed as three different clinical phenotypes due to different anatomical localization of the lesions. In PD, recent meta-analyses have identified four main clinical phenotypes, and clinicopathological correlations suggest that more severe and more rapid progression of pathology with chronological age, as well as the involvement of additional neuropathologies, differentiates these phenotypes. In DLB, recent large studies show that clinical diagnosis is too insensitive to identify the syndrome itself, although clinicopathological studies suggest variable clinical features occur in the different pathological forms of this syndrome (pure DLB, DLB with Alzheimer's disease (AD), and AD with amygdala predominant Lewy pathology). The recognition of considerable heterogeneity within the synucleinopathy syndromes is important for the identification of factors involved in changing their pathological phenotype.

Dementia with Lewy Bodies versus Alzheimer's Disease and Parkinson's Disease Dementia: A Comparison of Cognitive Profiles

BACKGROUND AND PURPOSE

It is particularly difficult to differentiate dementia with Lewy bodies (DLB) from the related dementias of Alzheimer's disease (AD) and Parkinson's disease dementia (PDD). Few studies have been designed to comparatively analyze detailed neuropsychological assessments of DLB patients and patients with AD and PDD.

METHODS

THREE GROUPS OF PATIENTS PARTICIPATED IN THIS STUDY: 10 with DLB, 76 with AD, and 17 with PDD, who had been diagnosed as probable DLB, AD, and PDD, respectively, according to the clinical criteria of the consortium on DLB, National Institute of Neurological and Communicative Diseases and Stroke/Alzheimer's Disease and Related Disorder Association, and the clinical diagnostic criteria for PDD. All patients were evaluated by careful neurological examination with detailed neuropsychological testing.

RESULTS

Significant differences among the three groups were found for attention, memory, and executive function, which included tasks of backward digit span, three-word recall, verbal delayed recall, and the Stroop test. Post hoc analysis revealed that the deficiencies of attention on the digit span task were greater in the DLB group than in the AD and PDD groups. The scores for episodic verbal memory tasks were significantly lower in the DLB and AD groups than in the PDD group. The performance in frontal executive function, as indicated by the Stroop test, was significantly worse in the DLB and PDD groups than in the AD group.

CONCLUSIONS

The results of the present study show that the pattern of cognitive dysfunction, in terms of attention, episodic memory, and executive functions, differ between patients with DLB and patients with AD and PDD.

Neuropathological correlates of volumetric MRI in autopsy-confirmed Lewy body dementia

The objective of this study was to determine the neuropathological correlates of regional medial temporal lobe volume measures on magnetic resonance imaging (MRI) in subjects with Lewy body dementia (LBD). Twenty-three autopsy-confirmed LBD cases with an MRI scan close to death (mean 1.5 years) were studied. MRI-based volumetric measures were calculated for total intracranial volume, hippocampus, entorhinal cortex, and amygdala. Quantitative neuropathological analysis of plaques, tangles, and Lewy bodies were carried out in the same regions. Spearman's rho was used to examine correlations between MRI volumes and neuropathology measures and linear regression to assess the relationship between neuropathology and MRI volumes. A significant inverse correlation was observed between normalized amygdala volume and percent area of Lewy bodies in the amygdala (r = -0.461, p = 0.035). There were no other significant correlations between regional MRI volume and measures of neuropathology. Lewy body, but not Alzheimer's disease (AD) pathology was associated with reduced amygdala volume in pathologically-verified LBD cases but neither Lewy body nor Alzheimer's disease pathology was associated with volume loss in the hippocampus or entorhinal cortex, suggesting other neuropathological factors account for atrophy in these structures in LBD.

The cognitive profile and CSF biomarkers in dementia with Lewy bodies and Parkinson's disease dementia

OBJECTIVE

Dementia with Lewy bodies (DLB) and Parkinson's disease dementia (PDD) may be viewed as different points on a continuum reflecting the regional burden and distribution of pathology. An important clinical consideration is overlapping Alzheimer's disease (AD) pathology, since it has been reported that associated AD pathology in DLB shortens survival and leads to a more rapid cognitive decline. We aimed to investigate cerebrospinal fluid (CSF) biomarkers and the associated cognitive profile in DLB and PDD.

METHODS

Clinically diagnosed DLB (n=47) and PDD (n=17) patients from a clinical follow-up programme were investigated. All performed mini mental state examination (MMSE) and went through lumbar puncture at baseline. CSF concentrations of total τ (T-τ), τ phosphorylated at threonine 181 (P-τ(181) ) and the 42 amino acid isoform of amyloid β, Aβ42 were determined.

RESULTS

We found significant differences in T-τ and Aβ42, with a higher level of T-τ and a lower level of Aβ42 in DLB compared to PDD. The combination of T-τ with Aβ42 showed better discrimination between DLB and PDD than either of the measures alone. In DLB, a CSF profile more like the one seen in AD was significantly correlated with worse performance on the orientation and memory of the MMSE.

CONCLUSION

The correlation suggests a possible link between a higher degree of AD pathology and a profile of more temporal disabilities on cognitive tests in DLB. This might aid in identifying a subgroup of patients with a greater burden of AD pathology in a clinical setting and could have important implications for prognosis.

Nonmotor symptoms in Parkinson’s disease: the dark side of the moon

Nonmotor symptoms may appear during the course of Parkinson’s disease, complicating the advanced phase in particular, but are also common in the premotor phase of Parkinson’s disease. The appearance of nonmotor manifestations represents a milestone, determining a worse prognosis and lower quality of life; however, they are often misdiagnosed and untreated. The spectrum of nonmotor symptoms encompasses mood disorders, psychosis, dementia, sleep disorders, impulse-control disorders and autonomic dysfunctions. This article describes these nonmotor symptoms and their management.

Effects of cholinesterase inhibitors in Parkinson's disease dementia: a review of clinical data

AIMS

Cognitive impairment and dementia are common features of Parkinson's disease (PD). Patients with Parkinson's disease dementia (PDD) often have significant cholinergic defects, which may be treated with cholinesterase inhibitors (ChEIs). The objective of this review was to consider available efficacy, tolerability, and safety data from studies of ChEIs in PDD.

DISCUSSIONS

A literature search resulted in the identification of 20 relevant publications. Of these, the treatment of PD patients with rivastigmine, donepezil, or galantamine was the focus of six, eleven, and two studies respectively, while one study reported use of both tacrine and donepezil. The majority of studies were small (<40 patients), with the exception of two large randomized controlled trials (RCTs) that are the main focus of this review. In the smaller studies, treatment benefits were reported on a range of outcome measures, though results were extremely variable. While the full results of a large RCT of donepezil in patients with PDD are not yet available, significant treatment differences were reported on the CIBIC-plus at the highest treatment dose. A trend toward improvement was also observed in treated patients on the ADAS-cog. The second large RCT found significant improvements in rivastigmine-treated patients compared with placebo on both the ADAS-cog (P < 0.001) and the ADCS-CGIC (P < 0.007), as well as on all secondary efficacy outcomes. Consequently, rivastigmine is now widely approved for the symptomatic treatment of mild to moderate PDD.

CONCLUSIONS

Taken together, these studies suggest that ChEIs are efficacious in the treatment of PDD.

Biomarkers: Parkinson disease with dementia and dementia with Lewy bodies

Dementia is a common feature in Parkinson disease (PD), the time of onset determining how patients are classified. Those patients where dementia develops prior to parkinsonism or during the first year of disease are designated as having dementia with Lewy bodies (DLB). In those where dementia develops over a year after the onset of motor signs, the condition is known as Parkinson's disease with dementia (PDD). While this seems at first sight to be a definitive way to distinguish these conditions, reality is rather different. The overlap between them is considerable, and there is much uncertainty associated with patients who have both motor symptoms and early cognitive impairment. The diagnosis is still based on medical history and clinical evaluation. It is not even certain that they can be accurately distinguished at autopsy. For this reason, the data concerning these entities have been reviewed, to examine various markers employed or measured in clinical, neuropathological, neuroimaging, and biochemical investigations. The concept of PDD and DLB being separate conditions is comparatively new, and the most promising tools with which to separate them at present are cerebrospinal fluid (CSF) markers and positron emission tomography (PET) scanning that indicate increased amyloid-beta burden in DLB compared to PDD. However as yet there are no markers that unequivocally distinguish between PDD and DLB.

Neurotransmitter changes in dementia with Lewy bodies and Parkinson disease dementia in vivo

OBJECTIVE

Although Parkinson disease with dementia (PDD) and dementia with Lewy bodies (DLB) show a wide clinical and neuropathologic overlap, they are differentiated according to the order and latency of cognitive and motor symptom appearance. Whether both are distinct disease entities is an ongoing controversy. Therefore, we directly compared patients with DLB and PDD with multitracer PET.

METHODS

PET with (18)fluorodopa (FDOPA), N-(11)C-methyl-4-piperidyl acetate (MP4A), and (18)fluorodeoxyglucose (FDG) was performed in 8 patients with PDD, 6 patients with DLB, and 9 patients with PD without dementia vs age-matched controls. Data were analyzed with voxel-based statistical parametric mapping and region of interest-based statistics.

RESULTS

We found a reduced FDOPA uptake in the striatum and in limbic and associative prefrontal areas in all patient groups. Patients with PDD and patients with DLB showed a severe MP4A and FDG binding reduction in the neocortex with increasing signal diminution from frontal to occipital regions. Significant differences between PDD and DLB were not found in any of the radioligands used. Patients with PD without dementia had a mild cholinergic deficit and no FDG reductions vs controls.

CONCLUSIONS

Patients with dementia with Lewy bodies and Parkinson disease dementia share the same dopaminergic and cholinergic deficit profile in the brain and seem to represent 2 sides of the same coin in a continuum of Lewy body diseases. Cholinergic deficits seem to be crucial for the development of dementia in addition to motor symptoms. The spatial congruence of cholinergic deficits and energy hypometabolism argues for cortical deafferentation due to the degeneration of projection fibers from the basal forebrain.

Selective molecular alterations in the autophagy pathway in patients with Lewy body disease and in models of alpha-synucleinopathy

BACKGROUND

Lewy body disease is a heterogeneous group of neurodegenerative disorders characterized by alpha-synuclein accumulation that includes dementia with Lewy bodies (DLB) and Parkinson's Disease (PD). Recent evidence suggests that impairment of lysosomal pathways (i.e. autophagy) involved in alpha-synuclein clearance might play an important role. For this reason, we sought to examine the expression levels of members of the autophagy pathway in brains of patients with DLB and Alzheimer's Disease (AD) and in alpha-synuclein transgenic mice.

METHODOLOGY/PRINCIPAL FINDINGS

By immunoblot analysis, compared to controls and AD, in DLB cases levels of mTor were elevated and Atg7 were reduced. Levels of other components of the autophagy pathway such as Atg5, Atg10, Atg12 and Beclin-1 were not different in DLB compared to controls. In DLB brains, mTor was more abundant in neurons displaying alpha-synuclein accumulation. These neurons also showed abnormal expression of lysosomal markers such as LC3, and ultrastructural analysis revealed the presence of abundant and abnormal autophagosomes. Similar alterations were observed in the brains of alpha-synuclein transgenic mice. Intra-cerebral infusion of rapamycin, an inhibitor of mTor, or injection of a lentiviral vector expressing Atg7 resulted in reduced accumulation of alpha-synuclein in transgenic mice and amelioration of associated neurodegenerative alterations.

CONCLUSIONS/SIGNIFICANCE

This study supports the notion that defects in the autophagy pathway and more specifically in mTor and Atg7 are associated with neurodegeneration in DLB cases and alpha-synuclein transgenic models and supports the possibility that modulators of the autophagy pathway might have potential therapeutic effects.

Cholinesterase inhibitors in Alzheimer's disease and Lewy body spectrum disorders: the emerging pharmacogenetic story

This review provides an update on the current state of pharmacogenetic research in the treatment of Alzheimer's disease (AD) and Lewy body disease (LBD) as it pertains to the use of cholinesterase inhibitors (ChEI). AD and LBD are first reviewed from clinical and pathophysiological perspectives. This is followed by a discussion of ChEIs used in the symptomatic treatment of these conditions, focusing on their unique and overlapping pharmacokinetic and pharmacodynamic profiles, which can be used to identify candidate genes for pharmacogenetics studies. The literature published to date is then reviewed and limitations are discussed. This is followed by a discussion of potential endophenotypes which may help to refine future pharmacogenetic studies of response and adverse effects to ChEIs.

Clinical measures of progression in Parkinson's disease

Despite all recent advances in symptomatic therapy Parkinson's disease (PD) continues to be a relentlessly progressive neurodegenerative disorder. Therefore therapies that will slow or hold disease progression are a major medical unmet need in PD. Clinical measures of disease progression that have been used in disease modification trials so far have focused on indices of progression of cardinal motor features like bradykinesia, rigidity, and tremor as captured by the UPDRS and the emerging need for effective dopaminergic symptomatic therapy. Progression of global disability in PD, however, is driven by additional factors beyond progressive nigrostriatal denervation leading to increasing severity of cardinal motor features. Progressive pathology in extranigral sites in the brain or peripheral autonomic nervous system contribute to poorly levodopa responsive motor symptoms like postural instability, freezing and falls or nonmotor symptoms. In addition treatment-induced motor complications also impact on PD disability. Although it is widely accepted that clinical progression of PD is multidimensional and in addition includes effects of aging, there is no consensus how to best implement more clinically meaningful endpoints for disease progression trials that would reflect these complex interactions impacting on the evolution of global disability in PD. There is an urgent need for biomarkers for disease progression that would faithfully reflect advancing neurodegeneration and resulted clinical disability in PD and that could be used in shorter term clinical trials testing putative disease modifying agents.

Parkin and PINK1 parkinsonism may represent nigral mitochondrial cytopathies distinct from Lewy body Parkinson's disease

Recent authors have concluded that Parkinson's disease (PD) is too heterogeneous to still be considered a single discrete disorder. They advise broadening the concept of PD to include genetic parkinsonisms, and discard Lewy pathology as the confirmatory biomarker. However, PD seen in the clinic is more homogeneous than often recognized if viewed from a long-term perspective. With appropriate diagnostic criteria, it is consistently associated with Lewy neuropathology, which should remain the gold standard for PD diagnostic confirmation. PD seen in the clinic has an inexorable course with eventual development of not only levodopa-refractory motor symptoms, but often cognitive dysfunction and prominent dysautonomia. This contrasts with homozygous parkin, PINK1 or DJ1 parkinsonism, characterized by young-onset (usually <40 years), and a comparatively benign course of predominantly levodopa-responsive symptoms without dementia or prominent dysautonomia. Parkin neuropathology is non-Lewy, with neurodegeneration predominantly confined to substantia nigra (and locus ceruleus), consistent with the limited clinical phenotype. Given the restricted and persistently levodopa-responsive phenotype, these familial cases might be considered "nigropathies". Based on emerging laboratory evidence linking parkin and PINK1 (and perhaps DJ1) to mitochondrial dysfunction, these nigropathies may represent nigral mitochondrial cytopathies. The dopaminergic substantia nigra is uniquely vulnerable to mitochondrial challenges, which might at least be partially attributable to large energy demands consequent to thin, unmyelinated axons with enormous terminal fields. Although sporadic PD is also associated with mitochondrial dysfunction, Lewy neurodegeneration represents a more pervasive disorder with perhaps a second, or different primary mechanism.

Verbal learning and memory in patients with dementia with Lewy bodies or Parkinson's disease with dementia

This study compared verbal learning and memory in patients with autopsy-confirmed dementia with Lewy bodies (DLB) and patients with Parkinson's disease with dementia (PDD). A total of 24 DLB patients, 24 PDD patients, and 24 normal comparison participants were administered the California Verbal Learning Test. The three groups were matched on demographic variables, and the two patient groups were matched on the Mattis Dementia Rating Scale. The results indicated that DLB patients recalled less information than PDD patients on all but one recall measure and displayed a more rapid rate of forgetting. In contrast, the PDD patients committed a greater percentage of perseveration errors than the DLB patients. The two groups did not differ in the percentage of recall intrusion errors or any measures of recognition. A discriminant function analysis (DFA) using short-delay cued recall, percentage of perseveration errors, and List B recall differentiated the DLB and PDD groups with 81.3% accuracy. The application of the DFA algorithm to another sample of 42 PDD patients resulted in a 78.6% correct classification rate. The results suggest that, despite equivalent levels of general cognitive impairment, patients with DLB or PDD exhibit a different pattern of verbal learning and memory deficits.

Incidental Lewy body disease: do some cases represent a preclinical stage of dementia with Lewy bodies?

Lewy pathology occurs in 8-17% of neurologically normal people age >60, termed incidental Lewy body disease (iLBD). It is often assumed to represent preclinical Parkinson disease (PD). However, some iLBD cases have diffuse pathology inconsistent with preclinical PD. We analyzed iLBD cases (α-synuclein immunohistochemistry) using the Braak PD staging scheme and determined if some had a neuropathological pattern suggestive of preclinical dementia with Lewy bodies (DLB). Of the 235 brains examined, 34 had iLBD (14.5%) and all but one could be assigned a Braak PD stage. The distribution of α-synuclein pathology in the 33 cases fell into three patterns: (1) diffuse cortical and subcortical α-synuclein pathology; (2) no cortical α-synuclein pathology, but a caudal-to-rostral ascending pattern, primarily involving brainstem; and (3) intermediate between these two categories. Also, 6/33 cases failed to follow the pattern of contiguous spread proposed by Braak. These findings suggest dichotomy in the distribution of iLBD: some cases fit the Braak ascending scheme, conceptually consistent with preclinical PD, whereas others displayed prominent cortical involvement that might represent preclinical DLB.

Cerebrospinal fluid biomarkers in Parkinson's disease with dementia and dementia with Lewy bodies

BACKGROUND

Clinical criteria for differentiating Parkinson's disease (PD) with dementia (PDD) from dementia with Lewy bodies (DLB) are unsatisfactory. Their existence as distinct clinicopathologic entities is still debated, although the burden of Alzheimer's disease (AD) pathology seems higher in DLB. Thus, analysis of cerebrospinal fluid (CSF) biomarkers (beta-amyloid(1-42) [Abeta42], total tau, and hyperphosphorylated tau [p-tau]) in living subjects might provide significant pathophysiological information on these diseases.

METHODS

Cerebrospinal fluid biomarkers were measured in DLB (n = 19), PDD (n = 18), and AD (n = 23) subjects matched for age, sex, and dementia severity, as well as in PD (n = 20) and normal control subjects (n = 20).

RESULTS

DLB showed the lowest mean CSF Abeta42 levels, with a negative association to dementia duration (rho = -.42, p = .07). In DLB patients, mean CSF total tau levels were significantly lower than in AD patients (508 +/- 387 vs. 960 +/- 619, respectively) but twofold to threefold higher than in PDD (286 +/- 184), PD (160 +/- 64), or normal control subjects (177 +/- 76), with a positive association to dementia severity (Mini-Mental State Examination: rho = -.54, p = .02; Milan Overall Dementia Assessment: rho = -.66, p = .002). PDD patients had mean CSF Abeta42 and total tau levels similar to those seen in PD patients. Hyperphosphorylated tau was significantly increased in the AD group only.

CONCLUSIONS

Cerebrospinal fluid Abeta42 and total tau have a different behavior in DLB and PDD, being related to duration and severity of dementia in DLB alone. Hyperphosphorylated tau is not significantly altered in these conditions.

Imaging amyloid deposition in Lewy body diseases

BACKGROUND

Extrapyramidal motor symptoms precede dementia in Parkinson disease (PDD) by many years, whereas dementia occurs early in dementia with Lewy bodies (DLB). Despite this clinical distinction, the neuropsychological and neuropathologic features of these conditions overlap. In addition to widespread distribution of Lewy bodies, both diseases have variable burdens of neuritic plaques and neurofibrillary tangles characteristic of Alzheimer disease (AD).

OBJECTIVES

To determine whether amyloid deposition, as assessed by PET imaging with the beta-amyloid-binding compound Pittsburgh Compound B (PiB), can distinguish DLB from PDD, and to assess whether regional patterns of amyloid deposition correlate with specific motor or cognitive features.

METHODS

Eight DLB, 7 PDD, 11 Parkinson disease (PD), 15 AD, and 37 normal control (NC) subjects underwent PiB-PET imaging and neuropsychological assessment. Amyloid burden was quantified using the PiB distribution volume ratio.

RESULTS

Cortical amyloid burden was higher in the DLB group than in the PDD group, comparable to the AD group. Amyloid deposition in the PDD group was low, comparable to the PD and NC groups. Relative to global cortical retention, occipital PiB retention was lower in the AD group than in the other groups. For the DLB, PDD, and PD groups, amyloid deposition in the parietal (lateral and precuneus)/posterior cingulate region was related to visuospatial impairment. Striatal PiB retention in the DLB and PDD groups was associated with less impaired motor function.

CONCLUSIONS

Global cortical amyloid burden is high in dementia with Lewy bodies (DLB) but low in Parkinson disease dementia. These data suggest that beta-amyloid may contribute selectively to the cognitive impairment of DLB and may contribute to the timing of dementia relative to the motor signs of parkinsonism.

Mechanisms of hybrid oligomer formation in the pathogenesis of combined Alzheimer's and Parkinson's diseases

Background

Misfolding and pathological aggregation of neuronal proteins has been proposed to play a critical role in the pathogenesis of neurodegenerative disorders. Alzheimer's disease (AD) and Parkinson's disease (PD) are frequent neurodegenerative diseases of the aging population. While progressive accumulation of amyloid β protein (Aβ) oligomers has been identified as one of the central toxic events in AD, accumulation of α-synuclein (α-syn) resulting in the formation of oligomers and protofibrils has been linked to PD and Lewy body Disease (LBD). We have recently shown that Aβ promotes α-syn aggregation and toxic conversion in vivo, suggesting that abnormal interactions between misfolded proteins might contribute to disease pathogenesis. However the molecular characteristics and consequences of these interactions are not completely clear.

Methodology/Principal Findings

In order to understand the molecular mechanisms involved in potential Aβ/α-syn interactions, immunoblot, molecular modeling, and in vitro studies with α-syn and Aβ were performed. We showed in vivo in the brains of patients with AD/PD and in transgenic mice, Aβ and α-synuclein co-immunoprecipitate and form complexes. Molecular modeling and simulations showed that Aβ binds α-syn monomers, homodimers, and trimers, forming hybrid ring-like pentamers. Interactions occurred between the N-terminus of Aβ and the N-terminus and C-terminus of α-syn. Interacting α-syn and Aβ dimers that dock on the membrane incorporated additional α-syn molecules, leading to the formation of more stable pentamers and hexamers that adopt a ring-like structure. Consistent with the simulations, under in vitro cell-free conditions, Aβ interacted with α-syn, forming hybrid pore-like oligomers. Moreover, cells expressing α-syn and treated with Aβ displayed increased current amplitudes and calcium influx consistent with the formation of cation channels.

Conclusion/Significance

These results support the contention that Aβ directly interacts with α-syn and stabilized the formation of hybrid nanopores that alter neuronal activity and might contribute to the mechanisms of neurodegeneration in AD and PD. The broader implications of such hybrid interactions might be important to the pathogenesis of other disorders of protein misfolding.

Palliative Management of Parkinson Disease: Focus on Nonmotor, Distressing Symptoms

Parkinson disease is a progressive neurodegenerative disease that commonly affects elderly persons. In the absence of neuroprotective or curative therapies, currently available therapies only provide symptomatic benefit. Progression to advanced Parkinson disease is often accompanied by functional dependence with increased risk of admission to a long-term care facility. The prevalence of Parkinson disease in long-term care facilities, within the United States, has been estimated to be between 5.2% and 10%. Patients with advanced Parkinson disease also experience other distressing motor and nonmotor conditions, such as motor complications, dementia, depression, gastrointestinal distress, orthostatic hypotension, pain, and psychosis, which can be a challenge for clinicians to manage. The presence of distressing symptoms along with the fact that Parkinson disease remains incurable necessitate discussion on a palliative care approach to this disorder. This article discusses the symptomatic management of distressing symptoms encountered in the long-term care resident with Parkinson disease, including motor complications and nonmotor features.

A critical reappraisal of current staging of Lewy-related pathology in human brain

Sporadic Parkinson disease (sPD) or brainstem-predominant type of Lewy body (LB) disease, and dementia with Lewy bodies (DLB), the two most frequent alpha-synucleinopathies, are progressive multisystem neurodegenerative disorders with widespread occurrence of alpha-synuclein (AS) deposits in the central, peripheral, and autonomic nervous system. For both LB-related disorders, staging/classification systems based on semiquantitative assessment of the distribution and progression pattern of Lewy-related/AS pathology are used that are considered to be linked to clinical dysfunctions. In PD, a six-stage system (Braak) has been suggested to indicate a predictable sequence of lesions with ascending progression from medullary and olfactory nuclei to the cortex, the first two presymptomatic stages being related to incidental LB disease, stages 3 and 4 with motor symptoms, and the last two (cortical) stages may be frequently associated with cognitive impairment. DLB, according to consensus pathologic guidelines, by semiquantitative scoring of AS pathology (LB density and distribution) in specific brain regions, is distinguished into three phenotypes (brainstem, transitional/limbic, and diffuse neocortical), also considering concomitant Alzheimer-related pathology. Retrospective clinico-pathologic studies, although largely confirming the staging system, particularly for younger onset PD with long duration, have shown that between 6.3 and 43% of the cases did not follow the proposed caudo-rostral progression pattern of AS pathology. There was sparing of medullary nuclei in 7-8.3% of clinically manifested PD cases with AS inclusions in midbrain and cortex corresponding to Braak stages 4 and 5, whereas mild parkinsonian symptoms were already observed in stages 2 and 3. There is considerable clinical and pathologic overlap between PD (with or without dementia) and DLB, corresponding to Braak LB stages 5 and 6, both frequently associated with variable Alzheimer-type pathology. Dementia often does not correlate with progressed stages of LB pathology, but may also be related to concomitant Alzheimer lesions or mixed pathologies. There is no relationship between Braak LB stage and the clinical severity of PD, and the predictive validity of this concept is doubtful, since large unselected, retrospective autopsy series in 30-55% of elderly subjects with widespread AS/Lewy-related pathology (Braak stages 5 and 6) reported no definite neuropsychiatric symptoms, suggesting considerable cerebral compensatory mechanisms. Applying the original criteria to large dementia samples, 49% of positive cases were not classifiable. Therefore, modified criteria for the categorization of Lewy-related pathology were proposed for patients with a history of dementia. The causes and molecular basis of the not infrequent deviations from the current staging schemes of AS pathology in PD and DLB, its relation to the onset of classical parkinsonian symptoms and for the lack of definite clinical deficits despite widespread AS pathology in the nervous system remain to be elucidated.

Animal models of Parkinson's disease progression

Parkinson's disease (PD) is a progressive neurodegenerative disorder whose etiology is not understood. This disease occurs both sporadically and through inheritance of single genes, although the familial types are rare. Over the past decade or so, experimental and clinical data suggest that PD could be a multifactorial, neurodegenerative disease that involves strong interactions between the environment and genetic predisposition. Our understanding of the pathophysiology and motor deficits of the disease relies heavily on fundamental research on animal models and the last few years have seen an explosion of toxin-, inflammation-induced and genetically manipulated models. The insight gained from the use of such models has strongly advanced our understanding of the progression and stages of the disease. The models have also aided the development of novel therapies to improve symptomatic management, and they are critical for the development of neuroprotective strategies. This review critically evaluates these in vivo models and the roles they play in mimicking the progression of PD.

Cortical alpha-synuclein load is associated with amyloid-beta plaque burden in a subset of Parkinson's disease patients

Amyloid-beta (Abeta) peptide pathology in Alzheimer's disease (AD) comprises extracellular plaques and cerebral amyloid angiopathy (CAA). In Parkinson's disease (PD), alpha-synuclein forms intraneuronal Lewy bodies (LBs), and cortical LBs are thought to play a major role in cognitive decline designated as PD with dementia. As there is increasing evidence that Abeta may also promote alpha-synuclein fibrillization, we assessed the relationship between LB pathology and Abeta deposition in 40 cases of PD and 20 age-matched controls. In five cortical areas, we established the severity of Abeta plaque load using an approach similar to that recommended by CERAD in AD. LB densities were determined using a morphometric approach. CAA was graded using previously described scales. The APOE genotype was established in 38 PD and 19 control cases. We have found that the overall Abeta plaque burden and, in particular, the diffuse plaque load shows a statistically significant 'large' correlation with the overall cortical LB burden. The strength of this correlation further increases in PD cases (about 50% of the cases) with moderate to high Abeta plaque load. The APOE epsilon4 allele is over-represented in this subgroup. Our data indicate a strong association between pathologically identifiable Abeta plaque burden and alpha-synuclein load in cerebral cortex and provide indirect evidence that Abeta pathology is likely to be an important factor contributing to cognitive decline in a subgroup of PD patients.