Diffuse Lewy body disease

Revisiting DLB Diagnosis: A Consideration of Prodromal DLB and of the Diagnostic Overlap With Alzheimer Disease

Efforts to clinically diagnose cases having dementia with Lewy bodies (DLB) identify those with a characteristic clinical syndrome (probable DLB) at the expense of missing an equal, if not greater, number of cases who have atypical presentations thought to be associated with coexisting Alzheimer pathologies. This article argues that further efforts should now be made to characterize this atypical group that constitutes cases previously identified postmortem as the Lewy body variant of Alzheimer disease (AD) or as AD with Lewy bodies. Since such fine distinction is unlikely to be achieved on clinical grounds alone, this new diagnostic category will require robust biomarker validation. Turning to a consideration of early/prodromal diagnosis of both typical and atypical DLB cases, it is suggested that there will be at least 3 prototypical forms-a mild cognitive impairment variant, associated with early visuoperceptual and attentional deficits; a delirium onset DLB with provoked or spontaneous delirium as the presenting features; and a psychiatric disorder DLB with its primary presentation as a late-onset affective disorder or psychosis.

Neuronal inclusions of α-synuclein contribute to the pathogenesis of Krabbe disease

Demyelination is a major contributor to the general decay of neural functions in children with Krabbe disease. However, recent reports have indicated a significant involvement of neurons and axons in the neuropathology of the disease. In this study, we have investigated the nature of cellular inclusions in the Krabbe brain. Brain samples from the twitcher mouse model for Krabbe disease and from patients affected with the infantile and late-onset forms of the disease were examined for the presence of neuronal inclusions. Our experiments demonstrated the presence of cytoplasmic aggregates of thioflavin-S-reactive material in both human and murine mutant brains. Most of these inclusions were associated with neurons. A few inclusions were detected to be associated with microglia and none were associated with astrocytes or oligodendrocytes. Thioflavin-S-reactive inclusions increased in abundance, paralleling the development of neurological symptoms, and distributed throughout the twitcher brain in areas of major involvement in cognition and motor functions. Electron microscopy confirmed the presence of aggregates of stereotypic β-sheet folded proteinaceous material. Immunochemical analyses identified the presence of aggregated forms of α-synuclein and ubiquitin, proteins involved in the formation of Lewy bodies in Parkinson's disease and other neurodegenerative conditions. In vitro assays demonstrated that psychosine, the neurotoxic sphingolipid accumulated in Krabbe disease, accelerated the fibrillization of α-synuclein. This study demonstrates the occurrence of neuronal deposits of fibrillized proteins including α-synuclein, identifying Krabbe disease as a new α-synucleinopathy.

Diagnosis and staging of Alzheimer disease

Rather than determining lesions "threshold" between "normal" cases and patients, we prefer to use clinicopathological correlations, assigning a given intellectual deficit to a given amount of lesions with a chosen level of probability. Because large amounts of A beta diffuse deposits may be found in the absence of dementia, we think advisable not to take them into account for the diagnosis. The diffusion of the neurofibrillary tangles in the paralimbic, limbic and isocortical areas (described by braak and Braak stages or by the number of areas containing tangles) and the density of isocortical senile plaques (A beta focal deposits) as assessed by the CERAD protocol are both correlated with the intellectual status but give complementary information. They should thus be jointly used. We analyzed the variability of the lesions counts, their coefficients of error, and their causes, as a first step toward standardization. We have shown, however, that semiquantitative estimates are presently more reproducible than quantitative measures.

The clinical manifestations of senile dementia of Lewy body type: a case report

A case of senile dementia of Lewy body type is presented. The clinical and neuropathological characteristics of the illness are discussed in the context of recent advances in the understanding of this condition.

Characterization of brain samples in studies of aging, Alzheimer's, and other neurodegenerative diseases

We review current understanding of the clinical and pathologic information needed for the determination of optimal brain tissue samples for the conduct of studies of Alzheimer's disease (AD). Characteristics that may distinguish AD from other dementing disorders are discussed. Selected considerations in the conduct of basic neurobiological studies are also outlined. Although the 28 NIA-funded Alzheimer's Centers can provide excellent clinical and neuropathological data, studies conducted outside these centers should also strive to gather the information suggested here. Clinical and neuropathological data should be used not only to classify subjects as control or AD, but also as variables that may significantly contribute to the analysis of neurobiological data obtained in the laboratory.

Clinicopathological studies of the dementias from an epidemiological viewpoint

Studies which examine patients with and without dementia during life and then examine brain tissue after death are extremely difficult to conduct. There are now several such studies published, representing a major contribution to the understanding of the pathologies of the dementias. These studies were not designed to represent population samples and, from an epidemiological viewpoint, they are flawed because none are population-based and none represent the full range of function observed during life. It is therefore important to examine the available studies for their contributions and biases.

Diffuse Lewy body disease in Japan

Thirty-seven Japanese autopsy cases with diffuse Lewy body disease (DLBD) were reviewed from a clinicopathological viewpoint. Based on the neuropathological finding of whether or not many concomitant senile plaques (SPs) and/or neurofibrillary tangles (NFTs) are present. DLBD is divided into two forms: a common form and a pure form. In the common form not only numerous Lewy bodies but also many SPs and/or NFTs are found in the cerebral cortex, whereas in the pure form there are no or few senile changes. Of the 37 cases, 28 cases had the common form, and 9 had the pure form of DLBD. In the common form all cases had shown progressive cortical dementia in the presenile or senile period. About 60% of the cases began with memory disturbance, while 25% showed Parkinson's or Shy-Drager syndrome initially. Parkinson's syndrome, consisting mainly of muscular rigidity and akinesia, was usually marked in the later stage, although there were also 8 cases (28.6%) in which no parkinsonian symptoms were detected even in the terminal stage. On the other hand, almost all cases with the pure form of DLBD showed juvenile Parkinson's syndrome, followed by progressive cortical dementia, although there was one presenile case with mild dementia and Parkinson's syndrome. These Japanese cases are compared with cases reported in Western countries.

Senile dementia of Lewy body type. A clinically and neuropathologically distinct form of Lewy body dementia in the elderly

A dementing syndrome has been identified in a group of psychiatric cases aged 71-90 years, presenting initially with a subacute/acute confusional state, often fluctuating and associated with visual hallucinations and behavioural disturbances. Clinically, these cases did not meet criteria for a diagnosis of Alzheimer's disease, and many were assigned to the multiinfarct dementia group, although no significant ischaemic lesions were evident at autopsy. Mild extrapyramidal features were apparent in a number of cases but the characteristic clinical triad of Parkinson's disease, i.e., tremor, rigidity, and akinesia, was absent. Detailed neuropathological examination revealed Lewy body formation and selective neuronal loss in brain stem and other subcortical nuclei, accompanied by Lewy body formation in neo- and limbic cortex, at densities well below those previously reported in diffuse Lewy body disease. A variable degree of senile degenerative change was present; numerous senile plaques and minimal neurofibrillary tangles in most cases. Neither the clinical nor the neuropathological features of this group are typical of Parkinson's or Alzheimer's disease, but suggest a distinct neurodegenerative disorder, part of the Lewy body disease spectrum, in which mental symptoms predominate over motor disabilities and lead to eventual psychogeriatric hospital admission. In a sequential series of autopsies conducted on clinically assessed demented patients, neuropathological analysis has indicated that such cases may comprise up to 20% of a hospitalized population of demented old people over the age of 70 years, an observation clearly relevant to the diagnosis and management of dementia in the elderly.

Tacrine, a drug with therapeutic potential for dementia: post-mortem biochemical evidence

A review of biochemical findings is presented which support the idea that Alzheimer's disease represents a condition for which tetrahydroaminoacridine (tacrine) may have a beneficial effect. There is evidence that clinical and histopathologic hallmarks of the disease relate to cholinergic and serotonergic dysfunction, with less obvious abnormalities in other neurotransmitters (aspartate, dopamine, gamma-aminobutyrate, glutamate, noradrenaline and somatostatin). Clinically relevant concentrations of tacrine may ameliorate the above presynaptic deficits without producing harmful (neurotoxic) effects of aspartate and glutamate. The disease seems to be associated with an early and clinically relevant degeneration of some neurons with cortical perikarya that release these amino acid transmitters. Studies are now required on the effect of tacrine on postulated harmful peptide-bond hydrolase activity within and around such cells.