Cerebral amyloid angiopathy in Lewy body disease

Prevalence, distribution, and severity of cerebral amyloid angiopathy differ between Lewy body diseases and Alzheimer's disease

Dementia with Lewy bodies (DLB), Parkinson's disease dementia (PDD), and Parkinson's disease (PD) collectively known as Lewy body diseases (LBDs) are neuropathologically characterised by α-synuclein deposits (Lewy bodies and Lewy neurites). However, LBDs also exhibit pathology associated with Alzheimer's disease (AD) (i.e. hyperphosphorylated tau and amyloid β (Aβ). Aβ can be deposited in the walls of blood vessels in the brains of individuals with AD, termed cerebral amyloid angiopathy (CAA). The aim of this study was to investigate the type and distribution of CAA in DLB, PDD, and PD and determine if this differs from AD. CAA type, severity, and topographical distribution was assessed in 94 AD, 30 DLB, 17 PDD, and 11 PD cases, and APOE genotype evaluated in a subset of cases where available. 96.3% AD cases, 70% DLB cases and 82.4% PDD cases exhibited CAA (type 1 or type 2). However only 45.5% PD cases had CAA. Type 1 CAA accounted for 37.2% of AD cases, 10% of DLB cases, and 5.9% of PDD cases, and was not observed in PD cases. There was a hierarchical topographical distribution in regions affected by CAA where AD and DLB displayed the same distribution pattern that differed from PDD and PD. APOE ε4 was associated with severity of CAA in AD cases. Topographical patterns and severity of CAA in DLB more closely resembled AD rather than PDD, and as type 1 CAA is associated with clinical dementia in AD, further investigations are warranted into whether the increased presence of type 1 CAA in DLB compared to PDD are related to the onset of cognitive symptoms and is a distinguishing factor between LBDs. Possible alignment of the the topographical distribution of CAA and microbleeds in DLB warrants further investigation. CAA in DLB more closely resembles AD rather than PDD or PD, and should be taken into consideration when stratifying patients for clinical trials or designing disease modifying therapies.

Prevalence of Concomitant Pathologies in Parkinson's Disease: Implications for Prognosis, Diagnosis, and Insights into Common Pathogenic Mechanisms

Pathologies characteristic of Alzheimer's disease (i.e., hyperphosphorylated tau and amyloid-β (Aβ) plaques), cardiovascular disease, and limbic predominant TDP-43 encephalopathy (LATE) often co-exist in patients with Parkinson's disease (PD), in addition to Lewy body pathology (α-synuclein). Numerous studies point to a putative synergistic relationship between hyperphosphorylation tau, Aβ, cardiovascular lesions, and TDP-43 with α-synuclein, which may alter the stereotypical pattern of pathological progression and accelerate cognitive decline. Here we discuss the prevalence and relationships between common concomitant pathologies observed in PD. In addition, we highlight shared genetic risk factors and developing biomarkers that may provide better diagnostic accuracy for patients with PD that have co-existing pathologies. The tremendous heterogeneity observed across the PD spectrum is most likely caused by the complex interplay between pathogenic, genetic, and environmental factors, and increasing our understanding of how these relate to idiopathic PD will drive research into finding accurate diagnostic tools and disease modifying therapies.

The Association of the Glymphatic Function with Parkinson's Disease Symptoms: Neuroimaging Evidence from Longitudinal and Cross-Sectional Studies

OBJECTIVE

Emerging pathological evidence suggests that there is an association between glymphatic dysfunction and the progression of Parkinson's disease (PD). However, the clinical evidence of this association remains lacking.

METHODS

In this study, the index for diffusion tensor image analysis along the perivascular space (ALPS index) was calculated to evaluate glymphatic function.

RESULTS

Overall, 289 patients with PD were enrolled in the cross-sectional study. The ALPS index was found to be negatively correlated with age, disease severity, and dyskinesia. In the longitudinal study, the information on a total of 95 PD patients with 5-year follow-up examinations was collected from the Parkinson's Progression Marker Initiative, 33 of which were classified into the low ALPS index group, and all others were classified into the mid-high ALPS index group based on the first tertile of the baseline ALPS index. The results of longitudinal regression indicated that there was a significant main group effect on autonomic dysfunction, as well as on activities of daily living. In addition, the low ALPS index group had faster deterioration in MDS-UPDRS part III and part II, Symbol Digit Modalities Test and Hopkins Verbal Learning Test. Path analysis showed that ALPS index acted as a significant mediator between tTau/ Aβ1-42 and cognitive change in the Symbol Digit Modalities Test score at year 4 and year 5.

INTERPRETATION

The ALPS index, an neuroimaging marker of glymphatic function, is correlated with PD disease severity, motor symptoms, and autonomic function, and is predictive of faster deterioration in motor symptoms and cognitive function. Additionally, glymphatic function may mediate the pathological role of toxic protein in cognitive decline. ANN NEUROL 2023;94:672-683.

The vascular risk factors and vascular neuropathology in subjects with autopsy-confirmed dementia with Lewy bodies

BACKGROUND

The frequency of vascular risk factors (VRFs) and the relationship between vascular pathology and cognitive function in neurodegenerative disease remains incompletely understood.

OBJECTIVE

The purpose of this study was to describe the frequency of VRFs and vascular pathology and explore the relationship between vascular pathology and cognitive function in dementia with Lewy bodies (DLB).

METHODS

This study included 363 autopsy-confirmed DLB and 753 Alzheimer's disease (AD) patients from the National Alzheimer's Coordinating Center (NACC) database. We used chi-squared test and analysis of variance to compare the VRFs and related factors in DLB and AD. Multinomial logistic regression and Spearman's correlation test were used to examine the relationship between vascular pathology and cognitive function.

RESULTS

No significant differences of VRFs were identified between DLB and AD. Alzheimer's disease patients had higher rates of microinfarcts (23.5% vs. 16.3%, p = 0.005) and moderate to severe amyloid angiopathy (45.9% vs. 36.1%, p = 0.002). In DLB patients, only cerebral amyloid angiopathy (CAA) pathology was negatively correlated with memory domain (r = -0.263, p < 0.001) and language (r = -0.112,p = 0.034). The rates of APOE ε4 allele carriers (60.0% vs. 44.9%, p = 0.004) and CAA pathology (45.9% vs.23.4%, p < 0.001) were much higher in the group with an intermediate likelihood of DLB than in the group with a high likelihood. There was a negative correlation between CAA pathology and memory (logical memory) in the group with an intermediate likelihood of DLB.

CONCLUSION

No difference of VRFs was identified between autopsy-confirmed DLB and AD. Cerebral amyloid angiopathy was shown to be an important pathology in DLB, which specifically correlated with memory and language. The groups with high and intermediate likelihood of DLB differed in terms of CAA pathology, and CAA pathology may play an important role in the development of DLB.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

The influence of cerebrovascular disease in dementia with Lewy bodies and Parkinson's disease dementia

INTRODUCTION

Lewy body dementia (LBD), including dementia with Lewy bodies (DLB) and Parkinson's disease dementia (PDD), is a common form of neurodegenerative dementia. The frequency and influence of comorbid cerebrovascular disease is not understood but has potentially important clinical management implications.

METHODS

A systematic literature search was conducted (Medline and Embase) for studies including participants with DLB and/or PDD assessing cerebrovascular lesions (imaging and pathological studies). They included white matter changes, cerebral amyloid angiopathy (CAA), cerebral microbleeds (CMB), macroscopic infarcts, micro-infarcts and intracerebral haemorrhage.

RESULTS

Of 4411 articles, 63 studies were included. Cerebrovascular lesions commonly studied included white matter changes (41 studies) and CMB (18 studies). There was an increased severity of white matter changes on magnetic resonance imaging (visualized as white matter hyperintensities, WMH), but not neuropathology, in LBD compared to PD without dementia and age-matched controls. CMB prevalence in DLB was highly variable but broadly similar to Alzheimer's disease (AD) (0-48%), with a lobar predominance. No relationship was found between large cortical or small subcortical infarcts or intracerebral haemorrhage and presence of LBD.

CONCLUSION

The underlying mechanisms of WMH in LBD require further exploration, as their increased severity in LBD was not supported by neuropathological examination of white matter. CMB in LBD had a similar prevalence as AD. There is a need for larger studies assessing the influence of cerebrovascular lesions on clinical symptoms, disease progression and outcomes.

The Relationship between the Static and Dynamic Balance of the Body, the Influence of Eyesight and Muscle Tension in the Cervical Spine in CAA Patients-A Pilot Study

Cerebral amyloid angiopathy (CAA) is one form of disease of the small vessels of the brain and can cause frequent cerebral hemorrhages as well as other types of stroke. The aim of the study was to analyze the static and dynamic balance of the body and changes in the tension of selected muscles of the cervical spine in patients with CAA after stroke, depending on visual control or its absence, compared to healthy volunteers. Eight stroke patients and eight healthy subjects were examined. The functional Unterberger test and the Biodex SD platform were used to test the dynamic equilibrium, on which the static equilibrium was also assessed. Muscle tension was tested with the Luna EMG device. In static tests, the LC muscle (longus colli) was significantly more active with and without visual control (p = 0.016; p = 0.002), and in dynamic tests, significantly higher results for MOS (p = 0.046) were noted. The comparison of the groups led to the conclusion that the more functional deficits, the more difficult it is to keep balance, also with eye control.

Cognitive Impairment in Parkinson's Disease: Epidemiology, Clinical Profile, Protective and Risk Factors

Cognitive impairment is a common non-motor symptom in Parkinson's Disease (PD) and an important source of patient disability and caregiver burden. The timing, profile and rate of cognitive decline varies widely among individuals with PD and can range from normal cognition to mild cognitive impairment (PD-MCI) and dementia (PDD). Beta-amyloid and tau brain accumulation, oxidative stress and neuroinflammation are reported risk factors for cognitive impairment. Traumatic brain injury and pesticide and tobacco exposure have also been described. Genetic risk factors including genes such as COMT, APOE, MAPT and BDNF may also play a role. Less is known about protective factors, although the Mediterranean diet and exercise may fall in this category. Nonetheless, there is conflicting evidence for most of the factors that have been studied. The use of inconsistent criteria and lack of comprehensive assessment in many studies are important methodological issues. Timing of exposure also plays a crucial role, although identification of the correct time window has been historically difficult in PD. Our understanding of the mechanism behind these factors, as well as the interactions between gene and environment as determinants of disease phenotype and the identification of modifiable risk factors will be paramount, as this will allow for potential interventions even in established PD.

Significance of cerebral amyloid angiopathy and other co-morbidities in Lewy body diseases

Lewy body dementia (LBD) and Parkinson's disease-dementia (PDD) are two major neurocognitive disorders with Lewy bodies (LB) of unknown etiology. There is considerable clinical and pathological overlap between these two conditions that are clinically distinguished based on the duration of Parkinsonism prior to development of dementia. Their morphology is characterized by a variable combination of LB and Alzheimer's disease (AD) pathologies. Cerebral amyloid angiopathy (CAA), very common in aged persons and particularly in AD, is increasingly recognized for its association with both pathologies and dementia. To investigate neuropathological differences between LB diseases with and without dementia, 110 PDD and 60 LBD cases were compared with 60 Parkinson's disease (PD) cases without dementia (PDND). The major demographic and neuropathological data were assessed retrospectively. PDD patients were significantly older than PDND ones (83.9 vs 77.8 years; p < 0.05); the age of LB patients was in between both groups (mean 80.2 years), while the duration of disease was LBD < PDD < PDND (mean 6.7 vs 12.5 and 14.3 years). LBD patients had higher neuritic Braak stages (mean 5.1 vs 4.5 and 4.0, respectively), LB scores (mean 5.3 vs 4.2 and 4.0, respectively), and Thal amyloid phases (mean 4.1 vs 3.0 and 2.3, respectively) than the two other groups. CAA was more common in LBD than in the PDD and PDND groups (93 vs 50 and 21.7%, respectively). Its severity was significantly greater in LBD than in PDD and PDND (p < 0.01), involving mainly the occipital lobes. Moreover, striatal Aβ deposition highly differentiated LBD brains from PDD. Braak neurofibrillary tangle (NFT) stages, CAA, and less Thal Aβ phases were positively correlated with LB pathology (p < 0.05), which was significantly higher in LBD than in PDD < PDND. Survival analysis showed worse prognosis in LBD than in PDD (and PDND), which was linked to both increased Braak tau stages and more severe CAA. These and other recent studies imply the association of CAA-and both tau and LB pathologies-with cognitive decline and more rapid disease progression that distinguishes LBD from PDD (and PDND).

Amyloid related cerebral microbleed and plasma Aβ40 are associated with cognitive decline in Parkinson's disease

Cerebral microbleeds (MBs) have been found in patients with cognitive decline. We aimed to examine whether MBs are associated with motor or cognitive decline in patients with Parkinson’s disease (PD). We enrolled 135 PD patients and 34 healthy controls. All participants underwent brain MRI and plasma biomarker assays, including tau, Aβ42, Aβ40, and α-synuclein. PD with dementia (PDD) was operationally defined as Mini-Mental State Examination (MMSE) score < 26 and advanced motor stage was defined as Hoehn-Yahr stage ≥ 3 during “on” status. The association between MBs and disease severity was examined using multivariate logistic regression models. More lobar MBs were observed in PD patients than controls (20.7% vs. 3.3%, p = 0.031). PDD patients had more lobar MBs (33.3% vs. 15.6%, p = 0.034), more white matter hyperintensity (p = 0.021) and reduced hippocampal volume (p = 0.001) than PD with normal cognition. The presence of lobar MB (odds ratio = 2.83 [95% confidence interval 1.04–7.70], p = 0.042) and severe white matter hyperintensity (3.29 [1.21–8.96], p = 0.020) was independently associated with PDD after adjusting for vascular risk factors and other confounders. Furthermore, plasma Aβ40 levels were associated the MMSE score (p = 0.004) after adjusting for age and sex. Our findings demonstrated that lobar MBs, reduced hippocampal volume, and elevated plasma Aβ40 levels are associated with PDD.

Cerebral amyloid angiopathy distribution in older people: A cautionary note

INTRODUCTION

Radiolabeled ligands for fibrillar amyloid beta (Aβ) peptides are used in positron emission tomography (PET) for dementia diagnosis. Current ligands do not discriminate parenchymal amyloid plaques from cerebral amyloid angiopathy (CAA).

METHODS

We undertook neuropathological examination of 65 older people (81.6 ± 7.96 (mean ± SD) years, 27F/38M): 15 with neuropathological diagnosis of AD, 25 with neuropathological diagnosis of other neurodegenerative dementias (Lewy body dementia and Parkinson disease dementia), and 25 without significant neurodegenerative pathology.

RESULTS

We observed CAA in non-Alzheimer's dementia (non-AD dementia) and control brains, of comparable extent to those with neuropathologically confirmed AD. Aβ-positive vessel density did not differ significantly between non-AD dementia and control groups. Across all subjects there was a highly significant correlation between vessel Aβ40 density and vessel Aβ42 density (Spearman rho = 0.855, P < .001). CAA was absent or sparse in subcortical white matter across all patient groups.

CONCLUSION

Our data indicate that CAA can be abundant in non-AD brains and raise a cautionary note regarding interpretation of amyloid PET imaging.

Novel clinicopathological characteristics differentiate dementia with Lewy bodies from Parkinson's disease dementia

Dementia with Lewy bodies (DLB) and Parkinson's disease dementia (PDD) known as Lewy body dementias have overlapping clinical and neuropathological features. Neuropathology in both includes combination of Lewy body and Alzheimer's disease (AD) pathology. Cerebral amyloid angiopathy (CAA), often seen in AD, is increasingly recognized for its association with dementia.

AIMS

This study investigated clinical and neuropathological differences between DLB and PDD.

METHODS

52 PDD and 16 DLB cases from the Queen Square Brain Bank (QSBB) for Neurological disorders were included. Comprehensive clinical data of motor and cognitive features were obtained from medical records. Neuropathological assessment included examination of CAA, Lewy body and AD pathology.

RESULTS

CAA was more common in DLB than in PDD (P = 0.003). The severity of CAA was greater in DLB than in PDD (P = 0.009), with significantly higher CAA scores in the parietal lobe (P = 0.043), and the occipital lobe (P = 0.008), in DLB than in PDD. The highest CAA scores were observed in cases with APOE ε4/4 and ε2/4. Survival analysis showed worse prognosis in DLB, as DLB reached each clinical milestone sooner than PDD. Absence of dyskinesia in DLB is linked to the significantly lower lifetime cumulative dose of levodopa in comparison with PDD.

CONCLUSIONS

This is the first study which identified prominent concurrent CAA pathology as a pathological substrate of DLB. More prominent CAA and rapid disease progression as measured by clinical milestones distinguish DLB from PDD.

Glial Fibrillary Acidic Protein in Serum is Increased in Alzheimer's Disease and Correlates with Cognitive Impairment

Reliable blood biomarkers for Alzheimer's disease (AD) are missing. We measured astroglial GFAP in patients with AD (n = 28), frontotemporal dementia (bvFTD, n = 35), Parkinson's disease (n = 11), Lewy body dementias (n = 19), and controls (n = 34). Serum GFAP was increased in AD (p < 0.001) and DLB/PDD (p < 0.01), and cerebrospinal fluid GFAP was increased in all neurodegenerative diseases (p < 0.001). Serum GFAP correlated with the Mini-Mental State Examination score (r= -0.42, p < 0.001) and might be a follow-up marker in clinical trials. Sensitivity and specificity of serum GFAP for AD versus bvFTD was 89% and 79% and might be the first blood biomarker in the differential diagnosis of AD and bvFTD.

Neuropathology of dementia in patients with Parkinson's disease: a systematic review of autopsy studies

BACKGROUND

Dementia is a common, debilitating feature of late Parkinson's disease (PD). PD dementia (PDD) is associated with α-synuclein propagation, but coexistent Alzheimer's disease (AD) pathology may coexist. Other pathologies (cerebrovascular, transactive response DNA-binding protein 43 (TDP-43)) may also influence cognition. We aimed to describe the neuropathology underlying dementia in PD.

METHODS

Systematic review of autopsy studies published in English involving PD cases with dementia. Comparison groups included PD without dementia, AD, dementia with Lewy bodies (DLB) and healthy controls.

RESULTS

44 reports involving 2002 cases, 57.2% with dementia, met inclusion criteria. While limbic and neocortical α-synuclein pathology had the strongest association with dementia, between a fifth and a third of all PD cases in the largest studies had comorbid AD. In PD cases with dementia, tau pathology was moderate or severe in around a third, and amyloid-β pathology was moderate or severe in over half. Amyloid-β was associated with a more rapid cognitive decline and earlier mortality, and in the striatum, distinguished PDD from DLB. Positive correlations between multiple measures of α-synuclein, tau and amyloid-β were found. Cerebrovascular and TDP-43 pathologies did not generally contribute to dementia in PD. TDP-43 and amyloid angiopathy correlated with coexistent Alzheimer pathology.

CONCLUSIONS

While significant α-synuclein pathology is the main substrate of dementia in PD, coexistent pathologies are common. In particular, tau and amyloid-β pathologies independently contribute to the development and pattern of cognitive decline in PD. Their presence should be assessed in future clinical trials where dementia is a key outcome measure.

TRIAL REGISTRATION NUMBER

CRD42018088691.

Atypical Clinical Manifestations of Cerebral Amyloid Angiopathy

PURPOSE

Cerebral amyloid angiopathy is a vasculopathy caused by β-amyloid deposition in cerebral arterioles and capillaries. It is closely linked to Alzheimer's disease and predisposes elderly patients to intracerebral hemorrhage, transient focal neurological episodes, and cognitive impairment. Because of a predilection for symptomatic hemorrhage, particularly in the frontal lobes, cerebral amyloid angiopathy may also cause a dysexecutive syndrome.

RECENT FINDINGS

In this case series, we describe presentations of classic clinical dementia syndromes which are not are widely thought to be associated with cerebral amyloid angiopathy, namely logopenic variant primary progressive aphasia (n = 3), normal pressure hydrocephalus (n = 3), and Lewy body dementia (n = 2). In every case, after a clinical diagnosis was established, neuroimaging, brain biopsy, and/or autopsy confirmed the presence of cerebral amyloid angiopathy. Cerebral amyloid angiopathy has significant clinical implications, and its ability to mimic and/or contribute to other clinical dementia syndromes can complicate its diagnosis. This series of cases broadens the range of clinical scenarios associated with cerebral amyloid angiopathy.

Review: Clinical, neuropathological and genetic features of Lewy body dementias

Lewy body dementias are the second most common neurodegenerative dementias after Alzheimer's disease and include dementia with Lewy bodies and Parkinson's disease dementia. They share similar clinical and neuropathological features but differ in the time of dementia and parkinsonism onset. Although Lewy bodies are their main pathological hallmark, several studies have shown the emerging importance of Alzheimer's disease pathology. Clinical amyloid-β imaging using Pittsburgh Compound B (PiB) supports neuropathological studies which found that amyloid-β pathology is more common in dementia with Lewy bodies than in Parkinson's disease dementia. Nevertheless, other co-occurring pathologies, such as cerebral amyloid angiopathy, TDP-43 pathology and synaptic pathology may also influence the development of neurodegeneration and dementia. Recent genetic studies demonstrated an important role of APOE genotype and other genes such as GBA and SNCA which seem to be involved in the pathophysiology of Lewy body dementias. The aim of this article is to review the main clinical, neuropathological and genetic aspects of dementia with Lewy bodies and Parkinson's disease dementia. This is particularly relevant as future management for these two conditions may differ.

APOE ɛ4/ɛ4 Is Associated with Aberrant Motor Behavior Through Both Lewy Body and Cerebral Amyloid Angiopathy Pathology in High Alzheimer's Disease Pathological Load

BACKGROUND

Aberrant motor behavior (AMB) is a neuropsychiatric symptom (NPS) prevalent in Alzheimer's disease (AD), known to cause great distress to both patients and caregivers. Apolipoprotein E4 (APOE4) is the most important genetic predictor of AD, and it has been associated with high NPS prevalence.

OBJECTIVE

To investigate the neuropathological substrates and risk factors associated with AMB in AD patients.

METHODS

Cases with Braak stage I-II and CERAD 0-1 were classified as Low AD (LAD), while Braak stage III-IV and CERAD 2 were grouped as Intermediate AD (IAD). Cases with Braak stage V-VI and CERAD 3 were classified as High AD (HAD) in accordance with NIA-Reagan criteria. All cases were stratified by APOE genotype, yielding No ɛ4 & ɛ4 and ɛ4/ɛ4 groups depending on ɛ4 copy number within APOE. Presence of AMB was assessed using NPI-Q.

RESULTS AND CONCLUSION

AMB increased in parallel with CERAD and Braak & Braak scores. Hypercholesterolemia, but no other cardiovascular risk factors, was associated with AMB in HAD. AMB prevalence in HAD was significantly increased in the presence of two APOEɛ4 alleles as compared to No ɛ4 & ɛ4. The relationship between homozygous APOE4 and AMB was strongly associated with the presence of both Lewy bodies and cerebral amyloid angiopathy pathologies in both sexes.

Distribution and Load of Amyloid-β Pathology in Parkinson Disease and Dementia with Lewy Bodies

Parkinson disease (PD), Parkinson disease with dementia (PDD), and Dementia with Lewy bodies (DLB) differ clinically with regard to the presence and timing of dementia. In this postmortem study, we evaluated whether the burden and distribution pattern of amyloid-β (Aβ) pathology differs among these disease entities. We assessed Aβ phases and neuritic plaque scores in 133 patients fulfilling clinical diagnostic criteria for PD, PDD, and DLB, and determined the presence and load of Aβ pathology in 5 cortical and 4 subcortical regions in a subset of patients (n = 89) using a multispectral imaging system. Aβ phases and neuritic plaque scores were higher in DLB versus PDD (both p < 0.001) and in PDD vs PD patients (p = 0.020 and 0.022, respectively). Aβ pathology was more often observed in the entorhinal cortex, amygdala and putamen in DLB versus PDD patients; Aβ load was higher in both cortical and subcortical regions. PDD patients had more frequent Aβ pathology in temporal cortex and higher Aβ load in cortical regions and striatum versus PD patients. Our findings suggest that the load and extent of Aβ pathology may contribute to cognitive dysfunction in PDD and the early-stage severe dementia in DLB.

Prevalence and clinical implication of microbleeds in dementia with lewy bodies in comparison with microbleeds in Alzheimer's disease

Background

Cerebral microbleeds (MBs) have been well investigated in Alzheimer's disease (AD), but not very extensively in non-AD dementias or in dementia with Lewy bodies (DLB).

Aims

To elucidate the clinical significance of MBs in DLB.

Methods

We compared the prevalence, locations and risk factors for MBs in 59 DLB and 81 AD patients. We visually counted MBs in each of the cortical and subjacent areas (frontal, temporal, parietal and occipital), the basal ganglia and the thalamus, and the brainstem and the cerebellar hemispheres on 1.5-tesla T2*-weighted gradient-recalled-echo MRI images. White matter lesions were semiquantified in fluid-attenuated inversion recovery images according to the Fazekas rating scale.

Results

While the prevalence of MBs was comparable, MBs tended to be more abundant in DLB than in AD in all brain areas with the exception of the occipital lobes. The number of MBs was positively associated with the severity of white matter lesions but not with other vascular risk factors in either AD or DLB. The presence of MBs could be associated with cognitive impairment at onset. MB-positive DLB patients showed less impairment on ¹²³I-metaiodobenzylguanidine myocardial scintigraphy (MIBG scintigraphy) images, supporting the notion of an inverse relationship between vascular lesions and Lewy body pathology.

Conclusion

It was suggested that an intricate association between Lewy body pathology, AD-type pathologies and vascular lesions seems to be related to the initial symptoms and results of MIBG scintigraphy in DLB.

Prevalence of cerebrovascular lesions in patients with Lewy body dementia: a neuropathological study

BACKGROUND

The co-existence of vascular pathology in patients with Lewy body dementia (LBD) is still a matter of debate. This study analyses the prevalence and the severity of cerebrovascular lesions in post-mortem brains of patients with LBD.

PATIENTS AND METHODS

Twenty brains of demented patients with autopsy-proven Lewy body disease were compared to 14 brains of age-matched controls.

RESULTS

Associated Alzheimer disease (AD) features, stages I-IV, were present in 70% of the LBD brains and in 7% of the controls (P<0.001). Cerebral amyloid angiopathy (CAA) was only present in 30% and lipohyalinosis in 10%. A semi-quantitative analysis, performed on a coronal section of a whole cerebral hemisphere and on a horizontal section through the pons and the cerebellum, revealed significantly more mini-bleeds in the LBD brains (P=0.007), predominantly in the cerebral cortex (P=0.03). Other cerebrovascular lesions were only rarely observed. Comparison of the LDB brains, with and without moderate AD features and CAA, showed no difference in the severity of the cerebrovascular lesions including mini-bleeds.

CONCLUSIONS

The prevalence of mini-bleeds in LBD brains appears to be independent from the co-existence of moderate AD pathology and CAA. It is more probably due to disturbances of the blood-brain barrier, related to the neurodegenerative process itself.

Prevalence and topography of small hypointense foci suggesting microbleeds on 3T susceptibility-weighted imaging in various types of dementia

BACKGROUND AND PURPOSE

The prevalence and topography of small hypointense foci suggesting microbleeds on 3T SWI in various types of dementia have not been systematically investigated. The purpose of this study was to determine the prevalence and topography of SHF on 3T SWI in patients with different dementia subtypes.

MATERIALS AND METHODS

We included 347 consecutive patients (217 women, 130 men; age range, 42-93 years; mean age, 74 years) who attended our memory clinic and underwent 3T SWI. They were divided into 6 groups: subjective complaints, MCI, AD, DLB, VaD, and FTLD. Two neuroradiologists evaluated the number and location of SHF on SWIs. Statistical analyses were performed to evaluate inter- and intragroup differences.

RESULTS

Of the 347 patients, 160 (46.1%) exhibited at least 1 small hypointense focus. This was true in 86% with VaD, 54% with DLB, 48% with AD, 41% with MCI, 27% with FTLD, and 22% with subjective complaints. With the subjective complaints group as a reference, the odds ratio adjusted by age, sex, and arterial hypertension was 9.2 (95% CI, 2.0-43.6) for VaD; 5.4 (95% CI, 1.2-24.3) for AD; 3.1 for DLB (95% CI, 1.1-8.8); 2.0 for MCI (95% CI, 0.5-8.1); and 1.5 for FTLD (95% CI, 0.4-5.4). There was a significant lobar predilection for AD, DLB, and FTLD groups (P < .05).

CONCLUSIONS

On 3T SWI, patients with VaD, AD, and DLB manifested a high SHF prevalence. In patients with AD, DLB, and FTLD, the SHF exhibited a lobar predilection.

In vivo detection of cortical microinfarcts on ultrahigh-field MRI

BACKGROUND AND PURPOSE

Cortical microinfarcts (CMIs) are detected as small foci restricted to the cerebral cortex in autopsy brains. CMIs are thought to be caused by cerebral amyloid angiopathy (CAA) in the elderly and may be a risk for dementia. We aimed to visualize CMIs, which remain invisible on conventional MRI, using double inversion recovery (DIR) and 3-dimensional fluid attenuated inversion recovery (3D-FLAIR) on 3-Tesla MRI.

METHODS

We prospectively performed DIR and 3D-FLAIR images in 70 subjects with Alzheimer disease (AD; n = 47), mild cognitive impairment (n = 14), AD with cerebrovascular disease (CVD; n = 3), vascular dementia (VaD; n = 2), CAA-associated intracerebral hemorrhage (ICH; n = 2) and one each of normal pressure hydrocephalus and dementia with Lewy bodies (DLB). Susceptibility-weighted imaging (SWI) was performed to detect cerebral microbleeds (CMBs).

RESULTS

Nine subjects (five of AD and one each of AD with CVD, ICH, VaD, and DLB) had small intracortical high signal lesions on both DIR and 3D-FLAIR images. All the nine subjects accompanied multiple lobar CMBs. These intracortical lesions were located in close proximity to CMBs, and were suggested to be CMIs.

CONCLUSIONS

DIR and 3D-FLAIR images may open a way to visualize CMIs.

Deep brain stimulation and cognitive decline in Parkinson's disease: a clinical review

Parkinson’s disease is a common and often debilitating disorder, with a growing prevalence accompanying global population aging. Current drug therapy is not satisfactory enough for many patients, especially after a few years of symptom progression. This is mainly due to the motor complications that frequently emerge as disease progresses. Deep brain stimulation (DBS) is a useful therapeutic option in carefully selected patients that significantly improves motor symptoms, functional status, and quality of life. However, cognitive impairment may limit patient selection for DBS, as patients need to have sufficient mental capabilities in order to understand the procedure, as well as its benefits and limitations, and cooperate with the medical team throughout the process of selection, surgery, and postsurgical follow-up. On the other hand it has been observed that certain aspects of cognitive performance may decline after DBS, namely when the therapeutic target is the widely used subthalamic nucleus. These are important pieces of information for patients, their families, and health care professionals. This manuscript reviews these aspects and their clinical implications.

Therapeutic potential of copper chelation with triethylenetetramine in managing diabetes mellitus and Alzheimer's disease

This article reviews recent evidence, much of which has been generated by my group's research programme, which has identified for the first time a previously unknown copper-overload state that is central to the pathogenesis of diabetic organ damage. This state causes tissue damage in the blood vessels, heart, kidneys, retina and nerves through copper-mediated oxidative stress. This author now considers this copper-overload state to provide an important new target for therapeutic intervention, the objective of which is to prevent or reverse the diabetic complications. Triethylenetetramine (TETA) has recently been identified as the first in a new class of anti-diabetic molecules through the original work reviewed here, thus providing a new use for this molecule, which was previously approved by the US FDA in 1985 as a second-line treatment for Wilson's disease. TETA acts as a highly selective divalent copper (Cu(II)) chelator that prevents or reverses diabetic copper overload, thereby suppressing oxidative stress. TETA treatment of diabetic animals and patients has identified and quantified the interlinked defects in copper metabolism that characterize this systemic copper overload state. Copper overload in diabetes mellitus differs from that in Wilson's disease through differences in their respective causative molecular mechanisms, and resulting differences in tissue localization and behaviour of the excess copper. Elevated pathogenetic tissue binding of copper occurs in diabetes. It may well be mediated by advanced-glycation endproduct (AGE) modification of susceptible amino-acid residues in long-lived fibrous proteins, for example, connective tissue collagens in locations such as blood vessel walls. These AGE modifications can act as localized, fixed endogenous chelators that increase the chelatable-copper content of organs such as the heart and kidneys by binding excessive amounts of catalytically active Cu(II) in specific vascular beds, thereby focusing the related copper-mediated oxidative stress in susceptible tissues. In this review, summarized evidence from our clinical studies in healthy volunteers and diabetic patients with left-ventricular hypertrophy, and from nonclinical models of diabetic cardiac, arterial, renal and neural disease is used to construct descriptions of the mechanisms by which TETA treatment prevents injury and regenerates damaged organs. Our recent phase II proof-of-principle studies in patients with type 2 diabetes and in nonclinical models of diabetes have helped to define the pathogenetic defects in copper regulation, and have shown that they are reversible by TETA. The drug tightly binds and extracts excess systemic Cu(II) into the urine whilst neutralizing its catalytic activity, but does not cause systemic copper deficiency, even after prolonged use. Its physicochemical properties, which are pivotal for its safety and efficacy, clearly differentiate it from all other clinically available transition metal chelators, including D-penicillamine, ammonium tetrathiomolybdate and clioquinol. The studies reviewed here show that TETA treatment is generally effective in preventing or reversing diabetic organ damage, and support its ongoing development as a new medicine for diabetes. Trientine (TETA dihydrochloride) has been used since the mid-1980s as a second-line treatment for Wilson's disease, and our recent clinical studies have reinforced the impression that it is likely to be safe for long-term use in patients with diabetes and related metabolic disorders. There is substantive evidence to support the view that diabetes shares many pathogenetic mechanisms with Alzheimer's disease and vascular dementia. Indeed, the close epidemiological and molecular linkages between them point to Alzheimer's disease/vascular dementia as a further therapeutic target where experimental pharmacotherapy with TETA could well find further clinical application.

Prevalence and pathology of dementia with Lewy bodies in the oldest old: a comparison with other dementing disorders

BACKGROUND

While the prevalence of Alzheimer disease (AD) increases with age, little is known about the frequency of dementia with Lewy bodies (DLB) in the oldest old. A retrospective hospital-based study compared the relative prevalence of DLB among very old individuals.

METHODS

1,100 consecutive autopsy cases of demented patients aged over 70 years (mean age: 83.9 ± 5.4 years) were examined using standardized neuropathological methods and current diagnostic consensus criteria.

RESULTS

Evaluation of three age groups (8th-10th decade) showed a significant increase in the relative prevalence of AD with cerebrovascular lesions including mixed dementia, while AD with Lewy body (LB) pathology showed a mild but insignificant age-related increase. Both 'pure' AD and vascular dementia showed a mild but insignificant decline, while DLB (without severe AD pathology) decreased progressively. While the severity of Lewy pathology in DLB slightly decreased with age, concomitant Alzheimer-like pathology increased progressively.

CONCLUSION

Whether DLB in the oldest old represents a distinct group is a matter of discussion, but the relative prevalence of AD with LB in our sample remained fairly stable.

Prevalence of small cerebral bleeds in patients with a neurodegenerative dementia: a neuropathological study

BACKGROUND

Small cerebral bleeds are frequently observed on magnetic resonance imaging in patients with Alzheimer dementia (AD). Histological confirmations in post-mortem brains are scarce. This study describes the prevalence of cerebrovascular lesions and the quantification of the "bleeding load" in post-mortem brains of patients with neurodegenerative dementias.

PATIENTS AND METHODS

Forty-five brains of AD patients, 8 of dementia with Lewy bodies (DLB) and 12 of fronto-temporal dementia (FTD) were compared to 10 controls. Histological examination was performed for the evaluation of cerebral amyloid angiopathy (CAA), white matter changes (WMCs), micro-infarcts, and cerebral micro- and mini-bleeds (MnBs). The latter were evaluated semi-quantitatively on a coronal section of a whole cerebral hemisphere and on a horizontal section through the pons and cerebellum.

RESULTS

Arterial hypertension (AH) was the main vascular risk factor in the patients with AD and DLB (P<0.05). MnBs, consisting of small perivascular bleeds, were significantly more frequent (P<0.001) in AD brains. They were mainly and equally present in the cerebral cortex of AD and DLB brains (P=0.04). Combined AD and DLB pathologies were present in 15%. CAA and WMCs occurred more frequently in AD brains (P<0.001). Occasional MnBs were observed in 60% of the controls.

CONCLUSIONS

This neuropathological study confirms the frequent presence of MnBs and WMCs in AD brains. The relative high incidence of cortical MnBs in DLB brains is probably due to the high incidence of AH and the frequent association with AD and CAA.

Macrophages in Alzheimer's disease: the blood-borne identity

Alzheimer’s disease (AD) is a progressive and incurable neurodegenerative disorder clinically characterized by cognitive decline involving loss of memory, reasoning and linguistic ability. The amyloid cascade hypothesis holds that mismetabolism and aggregation of neurotoxic amyloid-β (Aβ) peptides, which are deposited as amyloid plaques, are the central etiological events in AD. Recent evidence from AD mouse models suggests that blood-borne mononuclear phagocytes are capable of infiltrating the brain and restricting β-amyloid plaques, thereby limiting disease progression. These observations raise at least three key questions: (1) what is the cell of origin for macrophages in the AD brain, (2) do blood-borne macrophages impact the pathophysiology of AD and (3) could these enigmatic cells be therapeutically targeted to curb cerebral amyloidosis and thereby slow disease progression? This review begins with a historical perspective of peripheral mononuclear phagocytes in AD, and moves on to critically consider the controversy surrounding their identity as distinct from brain-resident microglia and their potential impact on AD pathology.

Population studies of sporadic cerebral amyloid angiopathy and dementia: a systematic review

BACKGROUND

Deposition of amyloid-beta (Abeta) in vessel walls of the brain as cerebral amyloid angiopathy (CAA) could be a major factor in the pathogenesis of dementia. Here we investigate the relationship between dementia and the prevalence of CAA in older populations. We searched the literature for prospective population-based epidemiological clinicopathological studies, free of the biases of other sampling techniques, which were used as a comparison.

METHODS

To identify population-based studies assessing CAA and dementia, a previous systematic review of population-based clinicopathological studies of ageing and dementia was employed. To identify selected-sample studies, PsychInfo (1806-April Week 3 2008), OVID MEDLINE (1950-April Week 2 2008) and Pubmed (searched 21 April 2008) databases were searched using the term "amyloid angiopathy". These databases were also employed to search for any population-based studies not included in the previous systematic review. Studies were included if they reported the prevalence of CAA relative to a dementia classification (clinical or neuropathological).

RESULTS

Four population-based studies were identified. They showed that on average 55-59% of those with dementia displayed CAA (of any severity) compared to 28-38% of the non-demented. 37-43% of the demented displayed severe CAA in contrast to 7-24% of the non-demented. There was no overlap in the range of these averages and they were less variable and lower than those reported in 38 selected sample studies (demented v non-demented: 32-100 v 0-77% regardless of severity; 0-50 v 0-11% for severe only).

CONCLUSION

CAA prevalence in populations is consistently higher in the demented as compared to the non-demented. This supports a significant role for CAA in the pathogenesis of dementia.