Senile dementia of Lewy body type and Alzheimer type are biochemically distinct in terms of paired helical filaments and hyperphosphorylated tau protein

The organization and anatomy of narrative comprehension and expression in Lewy body spectrum disorders

OBJECTIVE

Patients with Lewy body spectrum disorders (LBSD) such as Parkinson's disease, Parkinson's disease with dementia, and dementia with Lewy bodies exhibit deficits in both narrative comprehension and narrative expression. The present research examines the hypothesis that these impairments are due to a material-neutral deficit in organizational executive resources rather than to impairments of language per se. We predicted that comprehension and expression of narrative would be similarly affected and that deficits in both expression and comprehension of narrative would be related to the same anatomic distribution of prefrontal disease.

METHOD

We examined 29 LBSD patients and 26 healthy seniors on their comprehension and expression of narrative discourse. For comprehension, we measured accuracy and latency in judging events with high and low associativity from familiar scripts such as "going fishing." The expression task involved maintaining the connectedness of events while narrating a story from a wordless picture book.

RESULTS

LBSD patients were impaired on measures of narrative organization during both comprehension and expression relative to healthy seniors. Measures of organization during narrative expression and comprehension were significantly correlated with each other. These measures both correlated with executive measures but not with neuropsychological measures of lexical semantics or grammar. Voxel-based morphometry revealed overlapping regressions relating frontal atrophy to narrative comprehension, narrative expression, and measures of executive control.

CONCLUSIONS

Difficulty with narrative discourse in LBSD stems in part from a deficit of organization common to comprehension and expression. This deficit is related to prefrontal cortical atrophy in LBSD.

The Relationship between Parkin and Protein Aggregation in Neurodegenerative Diseases

The most prominent changes in neurodegenerative diseases are protein accumulation and inclusion formation. Several neurodegenerative diseases, including Alzheimer's, the Synucleinopathies and Tauopathies share several overlapping clinical symptoms manifest in Parkinsonism, cognitive decline and dementia. As degeneration progresses in the disease process, clinical symptoms suggest convergent pathological pathways. Biochemically, protein cleavage, ubiquitination and phosphorylation seem to play fundamental roles in protein aggregation, inclusion formation and inflammatory responses. In the following we provide a synopsis of the current knowledge about protein accumulation and astrogliosis as a common denominator in neurodegenerative diseases, and we propose insights into protein degradation and anti-inflammation. We review the E3-ubiquitin ligase and other possible functions of parkin as a suppressant of inflammatory signs and a strategy to clear amyloid proteins in neurodegenerative diseases.

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.

Parkin promotes intracellular Abeta1-42 clearance

Alzheimer's disease and Parkinson's disease are common neurodegenerative diseases that may share some underlying mechanisms of pathogenesis. Abeta(1-42) fragments are found intracellularly, and extracellularly as amyloid plaques, in Alzheimer's disease and in dementia with Lewy Bodies. Parkin is an E3-ubiquitin ligase involved in proteasomal degradation of intracellular proteins. Mutations in parkin, which result in loss of parkin function, lead to early onset Parkinsonism. Here we tested whether the ubiquitin ligase activity of parkin could lead to reduction in intracellular human Abeta(1-42). Lentiviral constructs encoding either human parkin or human Abeta(1-42) were used to infect M17 neuroblastoma cells. Parkin expression resulted in reduction of intracellular human Abeta(1-42) levels and protected against its toxicity in M17 cells. Co-injection of lentiviral constructs into control rat primary motor cortex demonstrated that parkin co-expression reduced human Abeta(1-42) levels and Abeta(1-42)-induced neuronal degeneration in vivo. Parkin increased proteasomal activity, and proteasomal inhibition blocked the effects of parkin on reducing Abeta(1-42) levels. Incubation of Abeta(1-42) cell lysates with ubiquitin, in the presence of parkin, demonstrated the generation of Abeta-ubiquitin complexes. These data indicate that parkin promotes ubiquitination and proteasomal degradation of intracellular Abeta(1-42) and demonstrate a protective effect in neurodegenerative diseases with Abeta deposits.

Both total and phosphorylated tau are increased in Alzheimer's disease

BACKGROUND

[corrected] Pathological tau protein concentrations in CSF are found in both Alzheimer's disease (AD) and frontotemporal dementia (FTD), but studies on brain tissue have suggested that the tau pathology in AD differs from that in FTD and that the difference may be related to the degree of phosphorylation. As CSF tau protein is increased after stroke, tau may also be implicated in the pathophysiology of vascular dementia, of which subcortical arteriosclerotic encephalopathy (SAE) is a putative subtype.

OBJECTIVES

To investigate the nature of tau protein in CSF and the involvement of total CSF tau and phosphorylated CSF tau (phosphotau) in various types of dementia.

METHODS

Using ELISAs for total tau and tau phosphorylated at Thr181 (phosphotau), the CSF concentrations of total tau and phosphotau were determined in patients with probable and possible AD (n=41 and 19, respectively), FTD (n=18), SAE (n=17), and Parkinson's disease (PD; n=15) and in age matched controls (n=17). All the antibodies stained the lower molecular weight bands, whereas only the antibodies that recognise phosphorylated tau stained the higher molecular bands.

RESULTS

Both CSF tau and CSF phosphotau were increased in probable AD compared with FTD (p<0.001), SAE (p<0.001), PD (p<0.001), and controls (p<0.001). CSF phosphotau was increased in possible AD compared with FTD (p<0.001) and SAE (p<0.001). CSF tau and CSF phosphotau were positively correlated in all the groups. Molecular weight forms of tau ranging from 25 kDa to 80 kDa were found in the CSF CONCLUSION: Both phosphorylated and unphosphorylated tau isoforms were present in the CSF, and tau protein appeared in both truncated and full length forms. The results suggest that the CSF concentrations of tau and phosphotau are increased in about two thirds of patients with probable AD and in half of those with possible AD but are normal in FTD, SAE, and PD compared with normal aging. Values in the normal range do not exclude AD.

Dementia with Lewy bodies. A distinct non-Alzheimer dementia syndrome?

Lewy body formation is central to the pathological phenotype of a spectrum of disorders. The most familiar of these is the extrapyramidal syndrome of idiopathic Lewy-body Parkinson's disease (PD). Studies of dementia in the elderly suggest that another manifestation of Lewy body pathology is equally or more common than Parkinson's disease. This syndrome of Dementia with Lewy bodies (DLB) has been given a number of diagnostic labels and is characterised by dementia, relatively mild parkinsonism, visual hallucinations, and fluctuations in conscious level. Although many of these features can arise in Parkinson's disease, the patients with DLB tend to have early neuropsychiatric features which predominate the clinical picture, and the diagnosis of the syndrome in practice is more concerned with the differential diagnosis of Alzheimer's disease (AD). Distinction from AD has clinical importance because of potentially differing therapeutic implications. Diagnostic guidelines for the clinical diagnosis and pathological evaluation of DLB are reviewed. Research into the disorder has centered around characterising the clinical, neuropsychological, pathological, neurochemical and genetic relationships with Alzheimer's disease on the one hand, and Parkinson's disease on the other. Many cases of DLB have prominent pathological features of AD and there are some shared genetic risk factors. Differences from the pathology of PD are predominantly quantitative rather than qualitative and evidence is discussed which suggests that DLB represents a clinicopathological syndrome within the spectrum of Lewy body disorders. The possibility that the syndrome represents a chance association of PD and AD is not supported by published studies.

Frequency of the apolipoprotein E epsilon 4 allele in a case-control study of early onset Parkinson's disease

OBJECTIVES

It has been suggested that Parkinson's disease and Alzheimer's disease may share a common or at least overlapping aetiology. The prevalence of dementia among cases of Parkinson's disease is known to be greater than expected in the general population. The frequency of the apolipoprotein epsilon 4 allele in a large case-control study of early onset Parkinson's disease has been examined.

METHODS

215 patients and 212 population based controls were recruited from the Republic of Ireland between 1992 and 1994. Cases had to have disease onset at 55 years or younger and be born after 1925.

RESULTS

The frequency of the epsilon 4 allele was almost identical between cases of Parkinson's disease (14.6%) and healthy controls (13.3%). There was no relation between epsilon 4 status and disease onset, disease duration, Hoehn and Yahr score, and disease progression. The frequency of the epsilon 4 allele was not increased among 10 patients with Parkinson's disease with dementia (10.0%) compared with the other patients without dementia (14.8%). There was no association between epsilon 4 allele status and either a history of smoking, family history of dementia, or Parkinson's disease, or being born in a rural area. The odds ratio for the ApoE epsilon 4 allele associated with Parkinson's disease was 1.10 (95% confidence interval (95% CI) 0.68-1.79), adjusting for age group, sex, and residential status. The pooled odds ratio from a meta-analysis of six studies of ApoE epsilon 4 status and Parkinson's disease was 0.94 (95% CI 0.69-1.27).

CONCLUSIONS

The results from our study as well as the pooled meta-analysis exclude any important role for ApoE epsilon 4 status in the development of Parkinson's disease. Our results similarly do not support its role either in dementia associated with Parkinson's disease or disease prognosis.